PGM Catalyst Handbook USA

the catalyst technical handbook

be selective

© 2008 Johnson Matthey Plc

Contents 1

INTRODUCTION

page 3

2

CATALYST RANGE

page 4

2.1

Heterogeneous Catalysts

2.4

Smopex® – Metal Scavengers 2.4.1

General Description

2.4.2

Smopex® Application

page 20

page 4

3

CATALYST SERVICES

page 21

Platinum Group Metal (PGM) Catalysts 2.1.1

General Description

3.1

Saving Time in Process Development

2.1.2

Liquid Phase Reactions

3.2

Catalyst Kits

2.1.3

Gas Phase Reactions

3.3

Chemical Development and Optimization

2.1.4

Choice of Catalyst Support

3.4

Metal Recovery Evaluation Service

2.1.5

Choice of Metal

3.5

Supply of Catalysts

2.1.6

Choice of Metal Location

3.6

2.1.7

Catalyst Deactivation

Partnership in Catalyst Development/Production

2.1.8

Safety and Handling

3.7

Technical Support for Catalytic Processes

2.1.9

Packaging and Storage

3.8

Refining of Catalyst Residues Smopex®

2.1.10 Catalyst Recovery and Shipment

Traditional Refining

Base Metal Catalysts 3.9

2.1.11 General Description and Applications

Metal Management

Sponge Metal™ Catalysts 2.1.12 General Description

4

2.1.13 Liquid Phase Reactions

CHEMISTRIES

page 24

2.1.14 Choice of Metal

4.1

2.1.15 Choice of Catalyst Particle Size

Hydrogenation

page 24

2.1.16 Catalyst Deactivation 2.1.17 Safety and Handling

4.1.1

2.1.18 Packaging and Storage

4.1.2

Aromatic Ring Compounds

4.1.3

Carbonyl Compounds


2.2

Homogeneous Catalysts 2.2.1 2.2.2

2.3

2

page 15

General Description The Catalytic Cycle

2.2.3

Choice of Catalyst

2.2.4

Product/Catalyst Separation

2.2.5

Catalyst Deactivation

2.2.6

Safety and Handling

2.2.7

Transport and Storage

2.2.8

Catalyst Recovery and Shipment

2.3.1

General Description

2.3.2

Catalyst Leaching and Recycle

4.1.4

Nitro and Nitroso Compounds

4.1.5

Halonitroaromatics

4.1.6

Reductive Alkylation

4.1.7

Reductive Aminations

4.1.8

Imines

4.1.9

Nitriles

4.1.10 Oximes 4.1.11

Hydrogenolysis Debenzylations Hydrodehalogenations Rosenmund Reductions

4.1.12 Transfer Hydrogenations

®

FibreCat Anchored Homogenous Catalysts

Carbon-Carbon Multiple Bonds

page 18

4.2

Dehydrogenation

page 41

4.3

Hydroformylation

page 43

4.4

Carbonylation

page 45

4.5

Decarbonylation

page 46

© 2008 Johnson Matthey

2

4.6

Hydrosilylation

4.12.1 Organic Synthesis

page 47

4.12.2 Gas Purification

4.7

Cross-Coupling Reactions page 48 4.7.1

Heck Reaction

4.7.2

Suzuki-Miyaura Coupling

4.7.3

Alpha-ketone Arylation

4.7.4

Carbon-heteroatom coupling – e.g.

4.13 Chiral Catalysis 4.13.1 Asymmetric Hydrogenation 4.13.2 Enantioselective Hydroamination 4.13.3 Enantioselective Alkyne Addition 4.13.4 Asymmetric Michael Addition

Buchwald-Hartwig amination

4.8

4.7.5

Organometallic Reactions

4.7.6

Sonogashira Reaction

4.7.7

Palladacycles

Cyclopropanation and Carbene Reactions

4.13.5 CATAXA™ Anchored Catalysts

5

TABLE : HETEROGENEOUS CATALYSTS

page 69

TABLE : HOMOGENEOUS CATALYSTS

page 73

TABLE : SMOPEX ® METAL SCAVENGING PRODUCTS

page 86

8

GLOSSARY OF TERMS

page 87

9

OTHER PUBLICATIONS

page 88

10

ADDRESSES OF LOCAL OFFICES

page 89

page 53

6 4.9

Isomerization

page 54

7

4.10 Oligomerization and

Polymerization

page 55

4.11 Selective Oxidation

page 56

4.11.1

Alcohols to Carbonyls or Carboxylic Acids

4.11.2

Dihydroxylation of Alkenes

4.11.3

Oxygen Insertion Reactions

4.11.4

Acetoxylation

4.12 Particulate Catalysts

3

page 63


page 59

3

1. Introduction Johnson Matthey is a recognized world leader in precious

The catalysts and technologies described herein are widely

and base metal catalysis. With staff in 38 countries, our

used in processes ranging from hydrogenation through

extensive network of resources enables us to provide a

carbonylations, coupling reactions and selective oxidations.

full range of services and products. These include the

In general, PGM catalysts combine high activity with

development and manufacture of catalysts and chemicals,

milder reaction conditions to give high selectivities for

analytical and characterization techniques, and the

specific transformations. Sponge metal catalysts (Ni, Cu,

recovery and refining of Platinum Group Metals (PGMs)

Co) offer our customers alternative process options,

from spent catalysts.

particularly in hydrogenation, reductive alkylation and dehydrogenation. Most importantly, we offer a range of

We are committed to providing our customers with the

solutions in chiral catalysis, including a unique range of

best technology for optimizing catalytic processes. In this

ligands and anchored chiral catalysts.

latest edition of our Catalyst Handbook, you will find our most recent developments in the areas of:

We continue to invest in state-of-the-art equipment for manufacture, testing, recovery and refining of spent

• Chiral Catalysis

catalysts. Our staff offers a high level of technical support,

• Coupling Catalysis

including catalyst recommendations and design, catalyst

• Metal Scavenging products – Smopex®

handling and metal management. The Johnson Matthey

• Anchored Homogeneous Catalysts – FibreCat®

name remains synonymous with accuracy, reliability and

• Sponge Metal™ Catalysts

integrity. Let our catalysis knowledge and experience

• Precious Metal Recovery Technology

work for you to improve and optimize your manufacturing processes.

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4

2. Catalyst Range 2.1

HETEROGENEOUS CATALYSTS

2.1.2 Liquid Phase Reactions with PGM Catalysts

Johnson Matthey offers a full range of heterogeneous catalysts:-

Liquid phase hydrogenations employing heterogeneous catalysts are multiple phase (gas – liquid – solid) systems

• Platinum group metal catalysts (PGM)

containing concentration and temperature gradients. In order

• Sponge metal (or skeletal) catalysts

to obtain a true measure of catalytic performance, heat

• Other base metal catalysts

transfer resistances and mass transfer resistances need to be understood and minimized. Mass transfer effects can

Platinum Group Metal (PGM) Catalysts 2.1.1 General Description

alter reaction times, reaction selectivity and product yields. The intrinsic rate of a chemical reaction can be totally obscured when a reaction is mass transport limited. For a reaction to take place in a multi-phase system, the

Heterogeneous PGM catalysts are in a different phase to

following steps must occur:-

the reactants and can be easily separated at the end of the reaction. Examples are:-

(i) dissolution of gas (e.g. H2) into the liquid phase (ii) diffusion of dissolved gaseous reactant through the bulk

• catalyst powder (Pd/C) slurried with liquid phase

liquid to the catalyst particle

reactants in a batch or continuous process which can be separated by filtration.

(iii) diffusion of the liquid reactants to the catalyst particle (iv) in-pore diffusion of the reactants to the catalyst surface

• catalyst granules – often called particulates – (Pt/Al2O3) as a bed through which reactants pass in the gas or liquid phase.

(v) adsorption of reactants on the catalyst, chemical reaction and desorption of products (vi) diffusion of products from the catalyst pores

The key properties of a catalyst are :High activity: for fast reaction rate, low catalyst

This figure illustrates the three potential mass transfer resistances in a multi-phase catalyst system.

loading and a short reaction time to maximize production throughput.

products and reduce purification costs.

Products

A (gas) + B (liquid)

High selectivity: to maximize the yield, eliminate by-

LIQUID

GAS

STAGNANT LIQUID LAYERS

A

POROUS CATALYST PARTICLE

A

High recycle capability: to minimize process costs.

B

Fast filtration rate: to separate rapidly the catalyst and

STAGNANT GAS LAYER Concentration A (g)

Concentration B (l)

final product, ensuring maximum production rates.

Heterogeneous catalysts are usually supported on a choice of materials such as activated carbon or alumina to

RESISTANCE TO GAS/LIQUID MASS TRANSPORT

RESISTANCE TO LIQUID/SOLID MASS TRANSPORT

{

{

{

Concentration A (l)

RESISTANCE TO DIFFUSION IN PORES OF CATALYST PARTICLE

improve metal dispersion, activity and catalyst durability. Supported PGM catalysts are used mainly in hydrogenation, dehydrogenation and selective oxidation

Mass Transport

reactions. Guidance is provided in Section 4 for the most

Rates of reaction will be affected by different process

appropriate catalyst for each specific reaction type.

variables depending on which step is rate limiting. A

Section 2.1 indicates the most important technical and

reaction controlled by gas–liquid mass transport i.e. rate

economic factors that will be of concern to the industrial

of mass transport of the gaseous reactant into the liquid,

user of these catalysts.

will be influenced mainly by reactor design, hydrogen pressure and agitation rate.

5


5

A reaction controlled by liquid–solid mass transport i.e.

are preferred when the presence of water in the reaction

the rate of mass transport of either gaseous reactant or

system is not detrimental. Handling paste is much easier

substrate from the bulk liquid to the external surface of

as it greatly reduces dusting and metal loss. The fire

the catalyst particle, will be influenced mainly by gas or

hazard, which occurs when organic vapors are present, is

substrate concentration, weight of catalyst in the reactor,

also reduced. When the use of a dry powder is

agitation and catalyst particle size distribution.

unavoidable, adequate precautions should be taken during handling. (see section 2.1.8.) Ceramic-based catalysts such

A reaction controlled by pore diffusion–chemical reaction

as those supported on alumina, silica or zeolites, are

i.e. the rate of reactant diffusion and chemical reaction

intrinsically safer and easier to handle because the support

within the catalyst particle, will be influenced mainly by

is denser than carbon and also is non-combustible.

temperature, reactant concentration, percent metal on the

However, different supports may change the catalyst

support, number and location of active catalytic sites,

activity.

catalyst particle size distribution and pore structure. To evaluate and rank catalysts in order of intrinsic catalyst activity, it is necessary to operate under conditions where mass transfer is not rate limiting.

For maximum economy in the use of PGM catalysts, it is important that the catalyst should be filtered from the reaction system without loss. Various types of leaf, cartridge and centrifuge filters are suitable for this

Reactors

operation, often in conjunction with a polishing filter. The recovery and refining of carbon-based catalyst residues is

A reactor used for liquid phase hydrogenations should

made easier if any filter precoat that may be required is of

provide for good gas–liquid and liquid–solid mass transport,

a combustible material such as cellulose. Many companies

heat transport and uniform suspension of the solid catalyst.

supply equipment suitable for filtering catalysts and

To facilitate this, a well agitated reactor is essential. The

Johnson Matthey can provide a list of contacts on request.

most effective means of agitation at any scale is stirring in

Johnson Matthey also offers Smopex® metal scavenging

a reactor fitted with suitable baffles.

fibers. (see section 2.4).

Alternatively, the reactant gas stream may be used to agitate the system and this may be particularly effective when combined with a centrifugal or turbo impeller.

2.1.3 Gas Phase Reactions with PGM Catalysts

Another very effective reactor design is the loop reactor. In this system the reactants are recirculated around a loop by means of a pump and the reaction occurs at the injection nozzle in the reactor. There is very effective gas/liquid/solid mixing at this nozzle.

Granular and pelleted catalysts are used in fixed bed gas phase reactions. The disposition of the catalyst beds, the reactor design and the size and shape of the pellets are dictated by the requirements of the heat transfer, fluid flow and pressure drop in the system. For example,

Many hydrogenation reactions are exothermic and it is necessary to remove the heat of reaction to maintain a constant reaction temperature. This can be achieved with an

highly exothermic reactions are usually performed in multi-tubular reactors with a coolant fluid surrounding the tubes to remove the heat generated.

internal cooling coil or tubes, a cooling jacket or in the case of a loop reactor, an external heat exchanger. A loop reactor system is particularly suitable for highly exothermic reactions.

Today, many industries demand high-purity gases for a wide range of uses. Besides chemical process feedstreams, other applications are in the electronics and

Continuous liquid phase reactions may be carried out in

nuclear industries. Contaminants, such as oxygen or

trickle columns using granular or extrudate catalysts. The

hydrogen, frequently need to be reduced in order to

reactant, dissolved in a suitable solvent if necessary, is

prevent the occurrence of problems such as:-

pumped to the column packed with catalyst. The reacting gas, generally hydrogen or oxygen, is passed co-currently or counter-currently through the catalyst bed. The product is collected continuously from the catalyst bed.

Catalyst Handling and Recovery

(i) promotion of unwanted side reactions (ii) corrosion (or chemical attack) of reactor materials or components (iii) unwanted modification of semiconductor properties in electronic components.

Activated carbon-based powder and paste catalysts are both used for liquid phase reactions but paste catalysts, containing approximately 50–60% water within the pores,

This has led to the development of a range of PGM catalysts on alumina supports for gas purification. These function by promoting catalytic combination of the contaminants within

6


6

the gas stream. For example, oxygen may be removed by combination with the stoichiometric quantity of hydrogen to

2.1.4 Choice of Catalyst Support for PGM Catalysts

form easily-removable water vapor. Section 4.12 provides detailed information on particulate catalysts and their use.

Although the main function of the catalyst support is to extend the surface area of the metal, the selection of the best type of support for a particular catalytic metal is

Catalyst Charging Care should be exercised when charging particulate catalysts to fixed bed reactors to minimize physical damage (generation of fines). Note that the catalyst should not fall more than 50–100cm. It should be evenly distributed as the bed is filled and not raked level. One of the best ways to fill a reactor evenly is with a canvas sock connected to an external hopper. The sock should be kept full and lifted slowly so that the catalyst flows out gently. The sock should be moved around the reactor to distribute the catalyst evenly and not left to discharge into a pile in one position. An alternative method is to fill the reactor with water and slowly add the catalyst such that it sinks gently down through the water.

Catalyst Activation

important as, in many reactions, the support can also substantially alter the rate and course of the reaction. The type of physical support is largely determined by the nature of the reaction system. When supported on a high surface area carrier, such as activated carbon, the catalytic metal is present in the form of discrete crystallites (typically a few nanometers diameter) and these give a very high catalyst area per unit weight of metal. For liquid phase reactions, powdered supports are invariably used, while in gas phase or continuous liquid phase reactions, a particulate support is used. The pore structure of the support may modify the role of the metal since the course of a reaction is often greatly influenced by the rates of diffusion of reactants and

Fixed-bed catalysts are sometimes supplied in the

products within the catalyst pores. In addition, the surface

unreduced form. These need to be activated before use in

area of a support can limit the PGM concentration that can

the following manner:-

be usefully employed.

(i) Load the catalyst carefully into the reactor and flush away air with flowing nitrogen (or other inert gas) at ambient temperature. (Ensure the volume of nitrogen exceeds 5 x the volume of the reactor)

Many of the commonly used catalyst supports, particularly carbon and alumina, are available in a large range of particle sizes, each with a range of surface areas and pore size distributions.

(ii) Introduce hydrogen at a concentration of 1% into the flowing nitrogen. Check for an exotherm in the catalyst

Reaction conditions may limit the choice of support.

bed. If it does not exceed 20˚C, then slowly increase the

The support should be stable at the temperature used

temperature (over >60 minutes) to the desired

and should not react with the solvent, feedstock or

reaction temperature. The low hydrogen concentration

reaction products.

will prevent a large exotherm when the catalyst species undergoes reduction.

2.1.4.1 Powdered Supports

(iii) Check for any exotherm and gradually increase the hydrogen concentration until 100% hydrogen.

A good powder catalyst will exhibit high attrition resistance to reduce catalyst losses by fines generation, good

(iv) Slowly introduce the feed to minimize any exotherms until the desired feed rate is achieved.

suspension characteristics for high catalyst activity and a fast filtration rate to minimize work–up time.

Note: minimum temperatures of 100˚C for Pd, 120˚C for Ru and 200˚C for Pt catalysts are generally required to ensure complete reduction.

These properties are functions of particle size and shape, pore volume, pore size distribution, surface area, activation procedure and material base. Values of these parameters may be optimum for one property but less good for another, e.g. a large catalyst particle size will produce a fast filtration rate but poor suspension characteristics.

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7

Thus, Johnson Matthey catalyst supports are selected to

PGM supported on alumina may prove to be more

incorporate a compromise of properties to generate

selective than the same metal supported on carbon.

catalysts of fast filtration with high activity and selectivity.

Silica is sometimes used when a support of low absorptive capacity with a neutral, rather than basic or

The following types of powder supports are most

amphoteric character is required. Silica-alumina can be

commonly used for PGM catalysts:

used when an acidic support is needed.

Carbon

Calcium Carbonate

Activated carbon powder is principally used as a support for catalysts in liquid phase reactions. As carbon is derived

Calcium carbonate is particularly suitable as a support for

from naturally occurring materials there are many variations,

palladium, especially when a selectively poisoned catalyst

each type having its own particular physical properties and

is required. The surface area of calcium carbonate is low

chemical composition. These differences can often be

but it finds applications when a support of low absorption

related to how the carbon is activated. The two traditional

or of a basic nature is required. The carbonates of

methods in use are steam and chemical activation of the

magnesium, strontium and zinc generally offer no

carbon char. In general, chemical-activated carbons tend to

advantage over calcium carbonate.

have higher BET surface areas than those of steamactivated carbons. By using different activation methods, the surface areas of different carbons can range from 500

Barium Sulfate Barium sulfate is another low surface area catalyst support. This support is a dense material and requires

m2g-1 to over 1500 m2g-1.

powerful agitation of the reaction system to ensure Trace impurities that may be present in certain reaction

uniform dispersal of the catalyst. A palladium on barium

systems can occasionally poison catalysts. The high

sulphate catalyst was traditionally used for the conversion

absorptive power of carbons used as catalyst supports

of acid chlorides to aldehydes (Rosenmund Reduction)

can enable such impurities to be removed, leading to

together with an in situ partial poison to improve the

longer catalyst life and purer products.

selectivity. In this application, however, it is being replaced

Carbon catalysts are produced in two physical forms, dry

increasingly by palladium on carbon catalysts for more

powder or paste. The latter form contains approximately

reproducible results.

50–60% by weight of water which is held within the pores of the carbon. There is no supernatant liquid and the ‘paste’ catalyst has the consistency of a friable powder.

2.1.4.2 Particulate Supports The use of granular or pelleted supports enables catalytic reactions to be carried out continuously in fixed bed

Graphite and Carbon Blacks

reactors. Vapor phase reactions have been carried out in Graphite powder and carbon blacks have a lower surface

this way, on an industrial scale, for many years.

area than activated carbon with graphite, generally in the range 5 m2g-1 to 30 m2g-1 (although special high surface

The advantages of this technique have been extended to

area graphites are available in the range 100 m2g-1 to 300

liquid phase reactions by the use of trickle-column

m2g-1). Graphites and carbon blacks are made synthetically

reactors. Since the formation of fine particles by attrition

and are therefore of higher purity than activated carbons,

must be kept to the minimum, high mechanical strength is a basic requirement of these catalysts. Such supports are

which are manufactured from naturally-occurring feedstocks. They are used for selective hydrogenation reactions or when a low porosity support is required to

available in various forms, such as spherical or cylindrical pellets, extrudates or irregular shaped granules.

minimize mass transfer problems or absorption of high

The metal may be deposited on or near the surface, or it may

value products.

be uniformly impregnated throughout the support. For most purposes, the diffusion of reactants into the pellet is slow, so

Alumina and Other Oxides

that surface impregnation is generally preferred. The quantity

Activated alumina powder has a lower surface area than most carbons, usually in the range 75

m2g-1

to 350

m2g-1.

It is a more easily characterized and less absorptive material than carbon. It is also non-combustible. Alumina is used instead of carbon when excessive loss of

of metal that may be deposited on the surface is dependent on the nature of the support. Catalyst life and performance are often affected by the method of preparation.

Alumina

expensive reactants or products by absorption must be

The most commonly-used pelleted support, alumina,

prevented. When more than one reaction is possible, a

exists in several phases, but the type usually employed is gamma–alumina. The type and form of the alumina

8


8

support may play a vital role in determining the overall course of the reaction, as may certain ions, which may be

CATALYST PARTICLE

deliberately added during catalyst manufacture. SECTION THROUGH CATALYST PARTICLE

When a support of high mechanical strength is required, or when a much more inert support is necessary, alpha–alumina with a surface area of less than 10 m2g–1 is available. In some continuous vapor phase processes the catalyst may eventually become deactivated, due to masking of

ENLARGED SECTIONS

the catalytic sites by the deposition of carbonaceous

EGGSHELL

INTERMEDIATE

UNIFORM

matter. The catalyst may be regenerated in situ by the controlled oxidation of this carbon, taking care to avoid large exotherms in the catalyst bed.

Carbon CATALYTIC METAL PARTICULATES AND SUPPORT PORE STRUCTURE

Carbon is usually not strong enough mechanically to

CARBON METAL ATOMS

withstand the arduous conditions encountered in an industrial gas phase reaction. However, granular carbon is particularly suitable for use as the support in trickle column reactors. Unlike alumina-based catalysts, carbon catalysts cannot be regenerated by a controlled oxidation process.

2.1.5 Choice of PGM

Eggshell shows palladium located on the exterior surface. Intermediate shows palladium located deeper within the pore structure. Uniform shows palladium evenly dispersed throughout the support structure.

Catalyst performance is determined mainly by the PGM component. A metal is chosen based both on its ability to

The catalysts are designed with different metal locations

complete the desired reaction and its ability not to perform

for reactions performed under different conditions of

unwanted side reactions. Palladium is the most versatile

pressure and temperature.

of the PGMs. It is typically the preferred metal for the hydrogenation of alkynes, alkenes, carbonyls in aromatic

Hydrogenation reactions are generally first order with

aldehydes and ketones, nitro compounds, reductive

respect to hydrogen. Thus, the reaction rate is directly

alkylations, hydrogenolysis and hydrodehalogenation

proportional to hydrogen pressure. With intermediate and

reactions. Platinum is typically the preferred metal for the

uniform catalyst types, an increasing proportion of the

selective hydrogenation of halonitroaromatics and

metal becomes accessible as the pressure increases.

reductive alkylations. Rhodium is used for the ring

When all the metal is available, the catalyst properties

hydrogenation of aromatics, while ruthenium is used for

closely parallel those of an eggshell catalyst. Therefore at

the higher pressure hydrogenation of aromatics and

higher pressures, intermediate and uniform catalysts have

aliphatic carbonyl hydrogenation. The use of mixed-metal

a higher activity than eggshell ones because of their

catalysts may also provide additional benefits in either

intrinsic greater metal dispersion due to metal located

selectivity and/or activity by a synergistic effect through the presence of both PGM metals.

The Effect of Hydrogen Pressure on the Hydrogenation Activity of Catalyst

2.1.6 Choice of PGM Location

Uniform Intermediate

Catalyst performance can be altered significantly by the

Eggshell

appropriate choice of support material, metal location and Matthey has developed techniques to deposit the metal selectively in the desired location and this is illustrated for a 5% palladium on carbon catalyst in the schematic.

ACTIVITY

dispersion within the pore structure of the support. Johnson

PRESSURE (PH 2 )

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9

deeper within the support pore structure. Thus, eggshell

“coking” on fixed-bed particulate catalysts. Fixed-bed

catalysts would be chosen for high activity at low

(except carbon supported) catalysts can be reactivated by

hydrogen pressure and uniform catalysts at high pressure.

the controlled combustion of the coke using an inert gas stream and/or steam with a low concentration of air. The

The location of catalytic metal deep into the support may lead to large in–pore diffusion resistance to reactants. This will result in increases in residence time and possible changes in selectivity. Thus the variation of the metal

combustion exotherm should be controlled not to exceed 20˚C. Powder catalysts can sometimes be reactivated by washing with suitable solvents, treating with oxidizing agents to breakdown the polymeric materials to smaller,

location can be used to adjust the selectivity of the catalyst. Eggshell catalysts have high activity at low reaction pressures in systems substantially free from catalyst poisons. If a catalyst poison is present, this can be overcome by locating the catalytic metal deeper into the support structure and hence increasing the metal dispersion. Such a catalyst will exhibit greater poison resistance because:-

more soluble species, and reducing to metal. Sintering occurs when crystallite growth of the catalytic metal decreases the metal surface area. This can arise by thermal sintering, particularly when operating above the Hüttig Temperature (see table below) or by a metal dissolution/re–precipitation mechanism. Thermal sintering can sometimes cause the collapse of the support pore structure e.g. a phase transition from

(i) the poison molecules often have high molecular weights and, unlike the smaller reactants, are

gamma to alpha-alumina resulting in encapsulation of the

unable to penetrate the pores where the catalytic

metal crystallite. Catalyst deactivation by sintering is

metal is located.

usually irreversible.

(ii) the increased metal area counteracts the constant area of metal rendered inactive by the poison.

Catalyst deactivation by physical loss of metal can arise in several ways. Metal may dissolve in the reaction medium

Variation of metal location, metal dispersion, metal loading (0.5–10%), catalyst pH and pore structure of the support has enabled the development of a large range of catalysts which are widely used in numerous liquid–phase and vapor–phase industrial processes.

2.1.7 PGM Catalyst Deactivation There are four main mechanisms for catalyst deactivation, namely poisoning, fouling, sintering and physical loss of metal.

and be stripped from the support. Metal may volatilize in high temperature gas phase reactions. The support material may be attacked and start to dissolve in some liquid-phase reactions and the insoluble catalyst fines pass through the filter system. Excessive movement of fixedbed catalysts due to pressure fluctuations can cause loss of catalyst fines by abrasion. The above forms of catalyst deactivation can be overcome by a more suitable choice of catalyst and/or reaction conditions.

2.1.8 Safety and Handling of Supported PGM Catalysts

Poisoning is caused by the irreversible adsorption of species on the catalyst surface. Such species include

Carbon-supported dry powder catalysts can undergo dust explosions in the same manner as carbon itself – and

heavy metals such as lead, copper and zinc; sulfur-

other carbonaceous powdered materials, such as flour or

containing species such as hydrogen sulfide and mercaptans; arsenic; amines and carbon monoxide. In general, it is not possible to remove the poisons by a washing or oxidation procedure (an exception is carbon monoxide).

stearic acid. The problem is minimized by avoiding dust formation during handling operations. Dusting is a bad practice in any case, giving rise to metal losses. As stated earlier, most of the platinum group metal catalysts supported on activated carbon can be used as

Fouling occurs when the catalyst surface is masked by polymeric materials or tars, and is often referred to as

water-wet pastes, which nevertheless behave as free

Table: The Hüttig Temperature of the Platinum Group Metals

10

Metal Hüttig

Pd

Pt

Rh

Ru

Ir

Os

Temperature (°C)

275

340

398

484

542

718


10

flowing powders. Paste catalysts are intrinsically safer and easier to handle and use than their dry powder analogues.

2.1.10 PGM Catalyst Recovery and Shipment

Pastes should always be used in preference to powders unless the presence of water is incompatible with the

When the catalyst has come to the end of its active life,

reaction system. The pastes are often more active

the spent material can be sent back to Johnson Matthey

catalysts than the corresponding powders.

for recovery of the PGM values. Each batch of residues received is rendered into a form suitable for evaluating the

Fresh PGM catalysts are essentially non–pyrophoric and can

exact metal content.

safely be exposed to air (in the absence of organic vapors). After use, the filtered supported catalyst should be After use, all catalysts containing absorbed hydrogen may

washed with a suitable solvent, followed by water (to

ignite if dried in air, especially in the presence of organic

reduce the organics content to a minimum) and returned

materials. A used, filtered catalyst should therefore be

as damp cake to the bags and drums. These should be

kept water-wet and out of contact with combustible

sealed and stored away from any combustible vapors.

solvents and vapors. PGM catalysts are extremely efficient at catalyzing the oxidation of low flash point organic

Since many supported catalysts are more pyrophoric after

compounds and can cause spontaneous combustion in

use in hydrogenation reactions due to hydrogen

the presence of these organic liquids (or their vapors) and

adsorption, they should ideally be filtered under an inert

oxygen (or air).

atmosphere. If this is not possible then the filter cake should not be allowed to ‘dry out’ during filtration, such

Care should always be taken when mixing catalysts and

that air is drawn through the cake before it is washed

organic materials. The risk of spontaneous ignition can be

thoroughly with water (to minimize the organics content)

reduced by cooling both the catalyst and the organic

and transferred as a damp cake to the drums for storage.

material(s) before mixing and performing the mixing operation under a blanket of inert gas, such as nitrogen. It is

Other materials contaminated with PGMs, such as wipes,

much safer to add solvent to catalyst than catalyst to solvent.

filter cloths or distillation residues should be returned in a separate marked drum for metal reclamation.

2.1.9 Packaging and Storage of PGM Catalysts

Gas-phase pelleted catalysts can usually be returned without any pretreatment for recovery of metal values.

Johnson Matthey catalysts are normally supplied in polyethylene bags (sealed with plastic clips) which are

Spent catalyst residues returned to Johnson Matthey are

packed in heavy-duty fiberboard drums. If required, steel

classed as materials for recycling and the transport of

or plastic drums can be employed. Also, on request, the

these residues is subject to current waste regulations.

catalysts can be packaged in pre–weighed quantities for

Johnson Matthey can offer advice about the regulations

batch-type processing requirements.

that apply to different materials, but the classification of any waste material is dependent upon the composition

PGM heterogeneous catalyst samples for laboratory

and characteristics of that material and is

evaluation are available packed in glass or plastic bottles.

the responsibility of the originator of the waste.

The catalysts should be stored in their sealed drums to prevent ingress of air and foreign gases until required for use. The drums should be kept in a cool, dry place under reasonable conditions (not exposed to the elements of weather and extremes of temperature – ideally keep between 5 to 30°C). They should not be stored near oils or flammable liquids or exposed to combustible vapors.

In addition to the regulations governing waste shipments, all movements of catalyst residues must be classified and labeled according to current international transport regulations. Material originating within the European Union should be classified and labelled for supply in accordance with Directive 1999/45/EC (as amended). To ensure safe treatment of the residues, Johnson Matthey requires a Material Safety Data Sheet for each residue returned.

After use, the empty bags and drums should be retained for return of the spent supported catalyst.

Further information and assistance on procedures for the return of residues and on the refining service can be obtained by contacting Johnson Matthey. The refining service is described in Section 3.8.


11

and loading of additives, the selectivity and activity of the

Base Metal Catalysts

catalyst can be further tuned by altering the support, metal

2.1.11 General Description and Applications

depositioning technique, and reduction and passivation

PRICAT® Supported Base Metal Catalysts

The table below shows some typical compositions and

method.

physical appearances of the main catalysts in the PRICAT®

Johnson Matthey’s PRICAT® products are supported base metal catalysts for applications in the agrochemical, fine

range. The table shows only the most widely used PRICAT® catalysts, and thus does not reflect the full range. Custom catalysts are available on request.

chemical, pharmaceutical intermediate and flavor & fragrance markets. These base metal catalysts are utilized in a vast range of reactions. The varying types and

Reactions performed by PRICAT®‚ catalysts include:

applications include copper based catalysts for dehydrogenation in slurry phase or fixed bed, powdered nickel for miscellaneous hydrogenations and alumina powders for dehydration . The main PRICAT® products are

-

Hydrogenation of sterically-hindered olefins

-

Hydrogenation of phenols

-

Ammonolysis of alcohols

-

kieselguhr and silica supported Ni, Cu and Co catalysts

Selective hydrogenation of phenol to cyclohexanol

functionalized with dopants. Most of the catalysts in the -

PRICAT® range come in tablet and powdered form. This

Hydrogenation of mono nitro-aromatics to the amine

allows the products to be applied in slurry phase, trickle -

bed and fixed bed reactors. The powdered catalysts are

Ring hydrogenation of alkyl-substituted phenols and aromatics

easy to handle since they are non-pyrophoric, free flowing -

and have excellent filtration qualities. The PRICAT® tablets,

Hydrogenation of aldehydes, ketones and aldoses to the corresponding alcohols

used in trickle and fixed-bed applications, usually come in -

the following sizes:

Reduction of nitriles to primary and secondary amines

-

-

3 x 3 mm

-

5 x 4 mm

-

6 x 5 mm

-

6 x 10 mm

Selective dehydrogenation of alcohols to the corresponding aldehydes and ketones

All PRICAT® catalysts are reduced and air passivated, allowing for ease of use. In general, activation can be done in situ under mild process conditions and low hydrogen partial pressures. PRICAT® catalysts are doped with cocatalytic metals and other additives in order to enhance performance in specific reactions. In addition to the type

PRICAT

Metal

Promotors MgO

Al2O3

Tablet

%

Ni 52/35

x

x

50

Kieselguhr

x

Ni 55/5

x

x

55

Kieselguhr

x

Ni 56/5

x

55

Kieselguhr

x

Ni 62/15

x

60

Kieselguhr

x

x

Ni 60/15

x

x

60

Kieselguhr

x

x

x

51

Silica

Cu 60/35

x

x

62

Silica

x

Co 40/55

x

x

40

Kieselguhr

x

ZrO2

Cr2O3

Powder

Cu 51/8

12

Support

MnO

x

x x


Sponge Metal Catalysts

Sponge Metal Catalyst Handling and Recovery

2.1.12 General Description Typically, Sponge Nickel catalysts are provided as a powder Sponge Metal

TM

catalysts are used for many of the same

covered in water (a slurry). The slurry contains

heterogeneous chemistries as PGM catalysts. The most

approximately 58-60% catalyst solids by weight. Catalyst

common type of reaction are three phase, gas-liquid-solid,

weight can be accurately determined using displacement.

reactions. Sponge Metal catalysts can be easily separated

Information on this method can be provided on request.

at the end of the reaction. For slurry phase Sponge Metal catalysts, settling, filtration and decantation are common

Activated Sponge Metal catalyst is shipped as an aqueous

ways to separate the catalyst. Other methods less

slurry, packaged in steel drums. The material is pyrophoric

commonly used in the industry are centrifugation and

and classified as hazardous. All packaging meets UN

magnetic separation. (activated Sponge Nickel

TM

catalysts

performance packaging guidelines for UN 1378.

are magnetic). Proprietary Johnson Matthey AMCAT® catalysts are Sponge Metal catalysts are prepared from alloys of

activated powdered encapsulated catalysts in which water

transition metals and aluminum. The aluminum is leached

has been displaced by an aliphatic amine. AMCAT

from the alloy structure, leaving behind an active metal

catalysts are in the form of solid 1/2 inch (13mm) cubes

surface covered in adsorbed hydrogen. The activated

that are nonpyrophoric. The active catalyst powder is

catalysts are stored under water to protect them from

released after charging into the desired feedstock and/or

oxidation. Sponge Metal catalysts are in the fully active

solvent.

form when shipped and require no preactivation prior to use.

In some reactions, to gain maximum catalyst efficiency, the catalyst is allowed to settle after reaction and the

Sponge Metal catalysts are used mainly in hydrogenation,

product is decanted off the top using a dip tube. When

reductive alkylation and dehydrogenation reactions.

this is not appropriate, the entire reaction mixture including product, solvent and catalyst can be fed to a

2.1.13 Sponge Metal Liquid Phase Reactions

filter or other separation device. If the catalyst will remain in the reactor for re-use, it may also be possible to incorporate filters into the reaction vessel to prevent

The principles which govern the use of Sponge Metal

downstream catalyst carryover.

catalysts are very similar to those described in Section 2.1.1 for heterogeneous PGM catalysts.

The filtering of Sponge Metal catalysts after use is recommended for maximum economy. Various types of

Considerations in the Industrial Use of Catalyst Reactors

leaf, cartridge, magnetic and centrifugal filters and separators are suitable for this operation. Downstream polishing filters are often used. If the catalyst settling and

Sponge Nickel catalysts are most often utilized in slurry-

product decantation steps are efficient, it may be possible

phase, batch, stirred tank reactors. Reactant, solvent (if

to use only a polishing filter.

present) and catalyst are charged to the vessel, air is replaced with an inert gas and the vessel is put under hydrogen pressure. The mixture is mechanically agitated, then heated to reaction temperature. After reaction, the mixture is cooled, agitation stopped and the catalyst allowed to settle. Product can be removed via diptube. Slurry-phase Sponge Metal catalysts are sometimes used in continuous stirred reactors with continuous catalyst separation and recycle. Continuous stirred reactors are beneficial for very fast reactions (e.g.dinitro and dinitrile reductions) prone to by-product formation.


13

Sponge Metal Catalyst Charging

2.1.15 Choice of Sponge Metal Catalyst Particle Size

Catalyst can be charged to the reaction vessel by several methods. In the simplest process, the catalyst drum is

Sponge Metal catalyst performance can be altered

placed in proximity to the opening of the reactor, the lid is

significantly by varying the particle size of the grind. The

removed and the entire contents are poured into the

standard mean particle size for Sponge Metal catalysts is

vessel. Alternately, the slurry is stirred with a shovel or

35 microns, however, other particle sizes are available

scoop and metered into the vessel. If a drum is overturned

upon request. Smaller catalyst particle size will, in general,

into another vessel, it is recommended that a sturdy 2 inch

increase catalyst activity but will reduce the ease of

to 4 inch steel grating be placed over the opening to

catalyst filtration or separation.

prevent the drum or drum liner from falling into the vessel.

2.1.16 Sponge Catalyst Deactivation Alternatively, the catalyst drum is emptied into an intermediate mechanically-stirred charge tank. The stirred

There are four main mechanisms for Sponge Metal

slurry would then be pumped or educted into the reaction

catalyst deactivation, namely poisoning, fouling, sintering

vessel in a separate step. Rather than overturning a drum

and chemical and physical degradation. Poisoning is

and pouring catalyst from the drum to a vessel, it is also

caused by the irreversible adsorption of species on the

possible to stir the catalyst mechanically in the drum and

catalyst surface. Such species include heavy metals such

then pump or educt the slurry into another vessel.

as lead, iron or mercury; sulfur containing species such as hydrogen sulfide and mercaptans; arsenic; amines and

Sponge Metal Catalyst Activation

carbon monoxide. Most poisoning is irreversible, i.e. it is not possible to remove the poisons by washing or other

Since activated Sponge Metal catalysts are already provided in the reduced state, no further pre-activation or

treatment. However, catalyst poisoning by carbon monoxide can be reversible.

pre-reduction treatments are necessary prior to the actual reaction step.

2.1.14 Choice of Sponge Metal

Sponge Metal active surfaces can be fouled by polymeric materials such as tars or “heavies” . Powder (slurry phase) catalysts can sometimes be reactivated by washing with suitable solvents.

The most common primary base metals formulated into Sponge Metal catalysts are nickel, cobalt and copper. Other base metals can be made into Sponge Metal catalyst formulations. Sponge Metal catalysts often

Loss of metallic surface area via sintering is more prevalent in copper catalysts than with nickel catalysts. Catalyst deactivation by sintering is irreversible.

contain other base metal promoters. Catalyst deactivation by chemical degradation can occur in Sponge Nickel catalysts, used mainly for hydrogenations, are supplied in both unpromoted and promoted forms. The most common promoters are molybdenum (A-7000 series) and iron and chromium (A-4000 series).

two ways. The active metal may dissolve in the reaction medium, or the residual aluminum in the catalyst structure can be leached away to the point where the activity decreases unacceptably. It may also be possible for catalysts to mechanically abrade in high-shear reaction

Sponge Cobalt™ catalysts find application in selective

systems.

hydrogenation, e.g. hydrogenation of nitriles to primary amines without the addition of ammonia as selectivity enhancer, or nitro group reduction in the presence of other functional groups such as halide. Sponge Cobalt catalysts can also be unpromoted and promoted. Copper is also incorporated into Sponge Metal catalysts as a primary component. Sponge Copper™ catalysts are more commonly used in dehydrogenation rather than reduction chemistries.

14


2.1.17 Safety and Handling


Activated Sponge Metal catalysts are all potentially pyrophoric. Fresh catalyst is shipped under a protective

When the catalyst has come to the end of its active life,

layer of water to prevent immediate oxidation by air.

Johnson Matthey offers services for reclamation of metal value. Each batch of residues received is rendered into a

In the event of a splash or spill, immediately flush with

form suitable for evaluating the exact metal content.

water to prevent catalyst drying. Dry catalyst can selfheat and serve as an ignition source for other flammable

After use, the filtered supported catalyst should be

materials. Contaminated cleaning materials should be

washed with a suitable solvent, followed by water to

disposed of in a safe place where they cannot cause a fire.

reduce organics content to a minimum. Spent catalysts should be sealed and stored away from any combustible

Sponge Metal catalysts contain adsorbed hydrogen on

vapors. Many supported catalysts are more pyrophoric

their surfaces. Depending on the history and storage

after use in a hydrogenation reaction due to hydrogen

conditions of the catalyst, small amounts of hydrogen can

absorption. Catalyst filtration should be done under an

evolve from the catalyst into the drums. Even though the

inert atmosphere and the filter cake should not be

drums are equipped with a self-venting mechanism, care

allowed to ‘dry out’. The filter cake should be washed

must be taken when opening containers. No ignition

thoroughly with water.

sources should be present in areas where drums are stored, handled and opened.

Other materials contaminated with base metals, such as wipes, filter cloths, distillation residues etc., should be

After use, all catalysts containing absorbed hydrogen may

returned in a separate marked drum for metal reclamation.

ignite if dried in air, especially in the presence of organic materials. A used, filtered catalyst should therefore be

Spent catalyst residues returned to Johnson Matthey are

kept water-wet and out of contact with combustible

classed as materials for recycling and the transport of

solvents and vapors.

these residues is subject to current waste regulations. Johnson Matthey can offer advice about the regulations

Please refer to the Material Safety Data Sheet for detailed

that apply to different materials, but the classification of

up-to-date information about hazards and safe handling

any waste material is dependent upon the composition

recommendations.

and characteristics of that material and is the responsibility of the originator of the waste.

2.1.18 Packaging and Storage In addition to the regulations governing waste shipments, Sponge Metal catalysts are typically supplied in open-head

all movements of catalyst residues must be classified and

steel drums. For high-purity requirements, custom drums

labeled according to current international transport

are available with a polyethylene insert. To accommodate

regulations. Material originating within the European Union

customers’ particular processes, the catalyst is available in

must also be classified and labeled for supply in

a variety of drum sizes, from 3-gallon (11 litre) to 55-gallon

accordance with Directive 1999/45/EC.

(208 litre). Also, on request, catalysts can be packaged in pre–weighed quantities to match batch size requirements.

To ensure safe treatment of the residues and to meet

Sponge Metal heterogeneous catalyst samples for

European Health and Safety legislation Johnson Matthey

laboratory evaluation are available packed in plastic bottles.

requires a Material Safety Data Sheet for each residue returned.

Catalyst should always be stored in sealed containers to prevent ingress of air and foreign gases until required for

Further information and assistance on the procedures for

use. Drums should be kept in a cool, dry place under

the return of residues and on the refining service offered

reasonable conditions (not exposed to the elements of

can be obtained by contacting your local Johnson Matthey

weather and extremes of temperature – (ideally keep

office. (see section 10).

between 5 to 30°C). Drums should not be stored near oils or flammable liquids or exposed to combustible vapors due to the risk of fire. After use, empty drums can often be retained for shipment of spent catalyst.


15

2.2

HOMOGENEOUS CATALYSTS

2.2.1 General Description

For example, a reaction with reagent 1 (R1) reacting with reagent 2 (R2) in the presence of a catalyst (M) to form product (P), where P=R1R2, could be written as

A homogeneously-catalyzed reaction contains the catalyst in the same phase as the reactants. Almost invariably the

R1 + R2

catalyst is dissolved in a liquid phase. Homogeneous

[M] → P

catalysis is an area of increasing importance within the chemical industry both for the manufacture of large-scale

The following scheme describes the catalytic cycle

industrial chemicals and complex fine chemicals. Examples of large-scale applications are:• acetic acid manufacture by methanol carbonylation using a rhodium complex and the more advanced technology using an iridium catalyst. • butyraldehyde and plasticizer alcohol (2–ethylhexanol) production by the hydroformylation of propylene using a rhodium catalyst. For PGM-catalyzed reactions, the advantages of a homogeneous system over a heterogeneous process are:(i) better utilization of metal – all of the catalytic metal is equally available to the reactants and hence a lower catalyst loading is required. (ii) exploitation of different metal oxidation states and ligands – offering a wide range of activity and, in particular, selectivity in a complex molecule. (iii) elimination of in–pore diffusion allowing kinetic rather than mass transfer control of reaction rates – ease of process scale–up. (iv) easy exotherm removal – no localized overheating and hence long catalyst lifetime.

The reaction intermediates involved in the catalytic cycle may or may not be capable of being isolated. The catalyst [M] is a metal atom with various chemical species bonded to it. These are called ligands. If the coordination number of the central metal atom is maintained during the catalytic cycle, it may be necessary for ligands to become detached during the course of the reaction. This is called ligand dissociation. In this example, the central metal atom has two ligands (L) which dissociate and then reattach later on in the catalytic cycle: P [ML2 ]

2.2.2 The Catalytic Cycle

R

1

For materials to act in a catalytic, as opposed to a stoichiometric mode, the catalyst must be recycled whilst

L

reactants are continuously forming product(s).

L 2

1

[R MR ]

1

[LMR ]

R

16

2


The ligands (L) may be the same, or different, and could

For example, compounds such as Rh4(CO)12, Rh6(CO)16,

include the solvent in which the reaction is being

Rh2Cl2(CO)4, Ru3(CO)12 and RuCl2(CO)6 are not readily

performed. In such cases, the solvent forms part of the

available in bulk quantities.

catalyst cycle and hence choice of solvent can be crucial in homogeneous catalysis.

In industry, stainless steel reactors are commonplace, so the addition of halide, even at ppm levels, can sometimes

Platinum Group Metals and all transition metals can form

cause plant corrosion. Hence, halide free catalysts or

such intermediates in which the nominal oxidation state

precursors might well be preferred in practice even though

and coordination number can be systematically varied.

the catalytic performance of the halide containing and

Transition metals have partially filled d–electron shells

non–halide containing materials may be identical,

which can form hybridized bonding orbitals between the central metal atom and the ligand. Suitable ligands are those capable of forming bonds with σ – and π – character such as carbonyls, alkenes and organophosphines. These ligands play a crucial role in homogeneous catalytic chemistry.

e.g. • Pd(acac)2, Pd-70 or [Pd(OAc)2]3, Pd-111 rather than palladium chloride solution • RhH(CO)(PPh3)3, Rh-42 rather than RhCl(CO)(PPh3)2, Rh-40 • Ruthenium nitrosyl nitrate solution rather than ruthenium chloride solution Although a specific reaction may be catalyzed by one

Much academic research has focused on the interaction of

particular compound, it is often more convenient to use

transition metal complexes with organic molecules. Many

a precursor and produce the actual catalyst in situ.

spectroscopic techniques have been used to identify the

Johnson Matthey can offer specific advice in reagent

transient catalytic intermediates. Precise knowledge of the

choice based on extensive experience in catalyst

intermediates and mechanisms involved can often help

selection.

process optimization. In some cases it has been possible to construct molecular

Precursor

Catalyst

Pd-111, [Pd(OAc)2]3 + PPh3

Pd-101,

Pd-101 is heat, light & air

Pd(PPh3)4

sensitive

RhI3

[Rh(CO)2I2]-

catalyst not readily available

less important than that of a heterogeneous catalyst.

RuCl3xH2O + oxidant

RuO4

RuO4 not commercially available

2.2.3 Choice of Catalyst

PPh3 = triphenylphosphine;

OAc = acetate ;

dba = dibenzylideneacetone

models of reaction intermediates whose conformation will lead to the formation of one particular product. This is particularly applicable to the synthesis of enantiomerically-

Reason for using precursor rather than catalyst

pure isomers. The homogeneous catalyst (or its precursor) is supplied as

or Pd-92, Pd(dba)x + PPh3

a chemical compound whose characteristics, i.e. purity, can be readily determined and controlled. It is dissolved in the reaction medium, hence its original physical form is

Many factors affect the selection of a particular homogeneous catalyst (or precursor). Reactions reported in the chemical literature will not necessarily have been

For a complete list of homogenous catalysts mentioned in

optimized with respect to reagent choice or operating

this handbook, see Section 6.

conditions. Reagents will have been chosen because they were readily available to the researcher and not because they were most suitable, e.g. • use of argon instead of oxygen-free nitrogen • use of PGM catalysts or precursors which do not lend themselves to economic scale-up • use of expensive reagents when cheaper ones would be just as effective


17

2.2.4 Product/Catalyst Separation

Poisoning is where the catalyst reacts irreversibly with an impurity e.g. the presence of carbon oxysulfide in carbon

A key consideration for homogeneous catalyst users is

monoxide will eventually deactivate the catalyst.

product/catalyst separation with subsequent product work–up and catalyst recycling.

Cluster formation can occur when there is insufficient ligand present to stabilize the catalyst, particularly when in a low

All common separation techniques have been employed in full-scale commercial operations as well as on the laboratory scale. These include :(i) product distillation, usually under reduced pressure (ii) liquid-liquid solvent extraction, particularly in applications where the spent catalyst is rendered soluble in water. (iii) crystallization of the product by addition of a precipitating solvent, such as diethyl ether, or a hydrocarbon, such as hexane. (iv) flash chromatography on neutral alumina or silica gel,

oxidation state. Eventually the catalyst activity will decline, but if the reason for this is known, it may be possible to reactivate in situ. In other cases this will not be possible. In extreme cases of cluster formation the catalyst may be precipitated. Also, when operating at high temperatures (above 100˚C) the catalyst may become unstable and decompose, resulting in precipitation. The fourth mechanism for deactivation is due to changes occurring to the ligand e.g. exposure of the catalyst to air, oxidizing triphenylphosphine (TPP) ligands to triphenyl phosphine oxide (TPPO).

2.2.6 Safety and Handling

using various solvents including acetone, hexane, ethyl acetate and mixtures of these. The spent catalyst is

Johnson Matthey has always been concerned to ensure that

retained on the column while the desired product

those products which are intrinsically hazardous are provided

passes through.

with sufficient information to permit safe handling and usage.

(v) catalyst adsorption followed by removal by filtration. Users should note that there is an obligation upon (vi) selective precipitation of the catalyst and removal from the reaction medium by filtration.

everyone involved in the use and handling of these materials to acquaint themselves with the potential hazards involved. Johnson Matthey will be pleased to offer

The desired product is then further purified by vacuum distillation or recrystallization. In addition to the separation techniques listed above, Johnson Matthey offers Smopex©, a unique metal scavenging system where metal binding functionality has

specific advice as necessary. Some of the compounds listed in this handbook have only been prepared on a relatively small scale for research purposes, and a complete investigation of their chemical, physical and toxicological properties has not been made.

been grafted onto fibers allowing the effective recovery of a range of precious metals. For more information on

2.2.7 Transport and Storage

Smopex© see section 2.4. Johnson Matthey will dispatch these compounds in a To be reused, a catalyst has to be rendered soluble again,

manner which conforms to all transport regulations. Steps

so further processing is essential. Such systems can be

will be taken to ensure their secure transportation. Each

quite complex, but the chemical transformations that are

batch of product is accurately sampled and analyzed to

made possible with homogeneous catalysis may justify

ensure batch to batch consistency. Johnson Matthey can

this extra processing.

dispatch material in pre–packed lots – either a fixed weight of compound or PGM per package. This can be done for

In some cases, the PGM homogeneous catalyst is so active that there is no economic need to recover the metal values due to the very low catalyst loading.

2.2.5 Catalyst Deactivation

both solid and liquid products. The materials should be kept in their original containers, protected from extremes of temperature until just before use. The containers should be resealed after dispensing.

All catalysts will eventually deactivate. There are four main mechanisms for deactivation namely: poisoning, cluster formation, precipitation and changes to the ligands. 18



lengths, (0.3mm) is standard) giving materials with different physical characteristics suited to a variety of reactor and filter combinations. For all fiber lengths,

When the catalyst has come to the end of its active life, the

recovery and recycle of the fiber-supported catalyst after

spent material can be sent back to Johnson Matthey for

reaction is readily achieved. Anchoring of the active

recovery of the platinum group metal values. It is in the

polymer chain to an inert polymer support ensures

catalyst user’s interest to concentrate any catalyst containing

excellent accessibility of the catalytic sites. This allows

liquors as much as possible before shipment, thereby:-

easy diffusion of the starting materials and products to

• reducing freight charges • reducing residue treatment charges However, in some instances, material can be more dilute and processed in AquaCat®. (see section.3.8). Spent catalyst materials returned to Johnson Matthey are classed as materials for recycling and the transport of these residues is subject to current waste regulations. Spent homogeneous catalyst residues typically contain over 50% organic compounds. Johnson Matthey has considerable experience in handling these types of materials. It is advisable that Johnson Matthey is consulted at the earliest possible opportunity to ensure that the material can be transported with a minimum of delay. In addition to the regulations governing waste shipments, all movements of catalyst residues must be classified and labeled according to current transport regulations. Material

and from the catalytic sites, in contrast to conventional polystyrene bead technology where slow diffusion can often reduce the reaction rate. Additionally, the polyethylene fiber is extremely robust and is not degraded by stirring, again in contrast to polystyrene beads. Johnson Matthey has tested these catalysts in a number of representative cross-coupling, hydrogenation, oxidation and hydrosilylation reactions There are currently 4 series of FibreCat® catalysts grouped according to the reactions they are used in: 1000 series:

Cross-coupling reactions

2000 series:

Hydrogenation reactions

3000 series:

Oxidation reactions

4000 series:

Hydrosilylation reactions

The full list of products is shown in Section 6.

Comparison of FibreCat® Catalysts with Homogeneous Catalysts:

originating within the European Union must also be classified and labeled for supply in accordance with

1000 series – Cross-coupling reactions

Directive 93/21/EEC (as amended).

Suzuki Reaction To ensure safe treatment of the residues and to meet local regulations, Johnson Matthey requires a Material Safety Data Sheet for each residue returned.

Suzuki (or Suzuki-Miyaura) reactions involve the coupling of organoboron compounds with aryl, alkenyl and alkynyl halides or triflates. This reaction is a very useful and

The refining service is described in Section 3.8.

generally high yielding method for cross-coupling of aromatic and heterocyclic aromatics.

2.3 F IBRE C AT ®

O

O Br + B(OH) 2

2.3.1 General Description1 FibreCat® is a new range of polymer-anchored homogeneous catalysts offering the selectivity benefits of

Catalyst, toluene K 2 CO 3 (2 equivalents), N 2 , 70C, 2h

FibreCat® technology offers a more active catalyst than the homogeneous equivalent.

homogeneous catalysts with the filtration/ separation benefits of heterogeneous catalysts. The active metal species are covalently bound to a

FibreCat® 1001

[Pd(OAc)2]3 + 12 PPh3

Pd: 4-bromoacetophenone molar ratio

1 : 120

1 : 100

polymer chain. This active polymer is further linked to an inert polyolefin fiber, which is insoluble in all common

% Yield

99.9

76.5

organic solvents. The fiber can be prepared in a variety of 1 S Collard et al, Catalysis of Organic Reactions (proceedings of 19th ORCS conference) 2002, 49-60


19

2000 series - Hydrogenation Reactions

2.

The hydrogenation of carbon-carbon double bonds using

Oxidation of alcohols to aldehydes FibreCat® catalyst can selectively oxidize alcohols to

organometallic complexes of rhodium is widely used in

aldehydes without over-oxidation to carboxylic acid.

organic synthesis. By anchoring coordination complexes to polymer supports, it should be feasible to combine the high selectivity and mild reaction conditions of the

For example, FibreCat® 3002 gives 70% conversion of benzyl alcohol to benzaldehyde with no over-oxidation to benzoic acid:

analogous homogeneous system with the ease of separation and recyclability of heterogeneous catalysts.

OH

O 10 mol% Ru as FibreCat 3002 Toluene

The fiber supports can also exert an influence on the selectivity and activity of the catalyst.

3 bar 60 C, 6 hours

In the selective hydrogenation of geraniol to citronellol1 and the selective hydrogenation of carvone to 7,8dihydrocarvone2, Rh FibreCat® catalysts exhibit similar

4000 series - Hydrosilylation Reactions

selectivities to their homogeneous counterparts. Platinum complexes are commonly used in hydrosilylation reactions as the exceptional activity of the catalyst allows the Pt to be used at very low levels. There can be issues,

OH

OH 1

though, with Pt being left in the product. This often needs to be removed, depending on the end application. These issues are overcome by using a supported homogeneous catalyst. O

O

In the reaction of trichlorosilane with tetradecene, the FibreCat® catalyst gives 85% conversion to product and a

2

colorless product, indicating that there is no Pt in the product. The hydrogenation of the least hindered double bond in these substrates is faster with homogeneous and C12 H 25

FibreCat® systems than other double bonds in the

+

Cl 3 SiH

C12 H 25

molecule meaning that the selective hydrogenation can be SiCl

achieved.

3000 series - Oxidation Reactions 1.

2.3.2 Catalyst Leaching and Recycle

The catalytic cis-dihydroxylation of olefins has traditionally been achieved with the use of osmium

Covalent linking of the metal catalyst to the polymer

complexes such as OsO4 and K2OsO2(OH)4. The use

support ensures that there is only very low leaching of

of homogeneous OsO4 is limited due to the hazards

metal into solution during the course of the reaction.

®

associated with its volatility and toxicity. FibreCat

As an example, analysis of the reaction liquor from the

lowers the volitility of the OsO4.

Suzuki coupling of 4–bromoanisole with phenyl boronic acid indicated that only ca 0.2% of the palladium was lost

In the cis-dihydroxylation of 1,2-cyclooctene to cis-1,2cyclooctane diol, FibreCat® 3003 gives 85%

to solution (less than 1 ppm palladium in solution).

conversion to product and <5ppm Os metal is

numerous times in this reaction and remained active

leached into solution.

throughout. The minimal leaching of the metal into the OH

0.1mol% Os-FibreCat 3:1t BuOH/H 2O

OH

Furthermore, the sample of catalyst recovered was reused

reaction product is particularly relevant when manufacturing pharmaceutical intermediates.

1.3 equiv amine-N-oxide 60C, 24 hours

20


2.4 SMOPEX® 2.4.1 General Description

2.4.2 Smopex® Application Precious metal (PM) catalysts have a wide range of

Smopex® is a new metal scavenging system for the recovery of low levels of precious metals (PM) from catalytic processes. Metal binding properties are introduced into thin polyolefin base fibers allowing fast metal recovery at high metal loadings giving vast improvements in process economics. Smopex® fibers have a unique advantage over traditional polymer beads in that the active groups are almost exclusively located on the surface of the fiber. This allows for the efficient recovery of PMs from a wide range of process solutions, and offers users the opportunity to overcome many of the issues associated with existing recovery techniques. The

applications in fine and bulk chemical manufacturing processes and provide clean and efficient routes to products in very high yields. The recovery of these PMs from process solutions is essential for improving process economics and enabling product purification. For their recovery, traditional techniques such as distillation and precipitation are being superseded by more sophisticated techniques, from solvent extraction to ion- or ligandexchange. In addition, environmental considerations almost always dictate low levels of PMs in effluent discharge, which makes Smopex the perfect recovery solution.

fibers are robust and do not degrade while stirring, In addition, they are insoluble in a wide range of commonly used solvents and are able to be used in both aqueous and organic media.

For application in the Pharmaceutical and Fine Chemical sector, Smopex® has been filed with the US Food and Drug Administration (FDA) in order that it can be used in pharmaceutical applications for the removal of metal from

The main benefits of Smopex include:

the product stream containing the Active Pharmaceutical Ingredient (API). In addition, Johnson Matthey has further

• Smopex® selectively removes ionic and non-ionic precious metal complexes from both aqueous and organic solutions

DMF numbers filed with the US FDA. Smopex-111, a thiol functionalised fiber, can now be used within the product stream containing the Active Pharmaceutical Ingredient (API). The DMF number is 18099.

• Smopex® can be used as a filter aid to remove colloidal precious metal particles from process liquors

The transportation of certain precious metal containing process material can be restricted, or simply not possible, for a number of reasons:

• Smopex® can remove metal from both homogeneously and heterogeneously catalysed

• Hazardous materials under shipment legislation

reactions • Liquors containing low levels of PMs may not be • The Smopex® system offers benefits including fast

cost effective to transport and treat

reaction kinetics and high precious metal loading on the fiber • The diffusion rate of the metal species to the active groups is often slow in alternative products

• Material composition confidentiality retention In these instances, Smopex® can be used at customer sites to remove the metal before shipment, making the shipment possible, non-hazardous, and cost effective.

• Smopex® fibres can be used to remove metal from the product stream.

See section 7 for a listing of the available Smopex® products.

• Smopex® fibres can recover metal down to ppb levels, for discharge to effluent.


21

3. Catalyst Services – how we work with you Johnson Matthey offers much more than the supply of a range of catalysts. Johnson Matthey looks to support

3.2 CATALYST KITS

customers from the start of the development of a new

Catalyst kits are available for a variety of research,

process or route, through its scale-up and on for the full

development and screening applications. Johnson Matthey

production life of the process.

offers the following kits:

We support the supply of catalyst with a complete

Cross Coupling

management system for precious metal, including the

Asymmetric Hydrogenation

refining of catalyst residues.

Heterogeneous PGM Catalysts – 40 samples FibreCat® – Anchored homogeneous catalysts

We provide a comprehensive, cost-effective and timeefficient package for all aspects of the development, implementation and execution of catalytic processes.

Smopex® – PGM metal scavengers Selective Oxidation Hydrogenation

These services are described below. For details of any of these services, please contact your local Johnson Matthey office. (section 10).

3.3 CHEMICAL DEVELOPMENT

3.1 SAVING TIME IN

Johnson Matthey has developed high throughput

PROCESS DEVELOPMENT When alternative process routes are being identified and evaluated, Johnson Matthey can provide advice as to which catalyst types and reaction conditions are most likely to give the desired activity and selectivity. Section 4 of this Handbook and the Catalytic Reaction Guide can be used to identify the catalyst systems suggested for particular transformations.

AND OPTIMIZATION

screening equipment and techniques, which are available for evaluating catalyst systems for customer reactions. These techniques can be used to identify suitable catalyst systems, and larger scale equipment is available to optimize the systems once identified. This work is done with customer–supplied feedstock to ensure that the catalyst system is the best for the profile of the material with which it will be used. This high throughput screening equipment is suitable for all reactive gas chemistries, as well as reactions under an inert atmosphere.

For specific reactions, a full catalyst recommendation can be provided by Johnson Matthey chemists, giving suitable catalysts, solvents, additives and process conditions. A catalyst recommendation from Johnson Matthey is the

All development work for customers at Johnson Matthey is conducted within a framework ensuring total confidentiality and the customer’s freedom to operate the process.

quickest route to a process with the desired activity and selectivity.

3.4 METAL RECOVERY EVALUATION SERVICE

Time and effort may also be saved later in the process as Johnson Matthey can at this stage advise on process

A key element of the efficiency of metal–catalyzed

issues such as catalyst recovery, or the selection of

processes is the recovery of the metal from the process

catalysts that are easy to handle at plant scale.

and the refining of the process residues. Johnson Matthey has developed methods for recovering metal in different

A list of standard catalysts is given in sections 5 and 6.

forms from process streams.

Many catalysts have been developed through in-house programs for specific reactions and Johnson Matthey is

When a process is in development, Johnson Matthey will

also able to formulate catalysts optimized for individual

evaluate the recovery of the metal from the process and

reaction conditions.

identify a refining route for the residues. This ensures that the process that is put into production is as clean, efficient

Samples of catalysts are available to customers. By working

and cost–effective as possible.

with us, you will ensure that the same catalysts that are used in the laboratory are available for use in the plant.

22


3.5 SUPPLY OF JOHNSON MATTHEY CATALYSTS

3.8 REFINING OF PGM CATALYST RESIDUES

By working with Johnson Matthey as the process is

As the largest refiner of secondary (i.e. recycled) platinum

developed, you will ensure that your chosen catalyst is

group metal materials in the world, Johnson Matthey is

available at scale to use in your process. Any catalyst

ideally placed to ensure the efficient recovery of the metal

supplied as a sample can be supplied at pilot and then at

values in your residues.

full production scale, to the same exacting standards. Traditionally, the recovery of metal has been through All catalysts or catalyst precursors from Johnson Matthey

incineration. (see Traditional Refining).

are supplied with full quality and health and safety documentation. All can be packed to individual customer

Johnson Matthey has now introduced novel technologies

requirements.

for the recovery of precious metals. These are detailed below:

Our export department can arrange for the delivery of catalyst across the world.

3.6 PARTNERSHIP IN CATALYST DEVELOPMENT AND PRODUCTION

Smopex® Smopex® is a unique metal ‘scavenging’ system where chemical groups are attached to fibers, which are then used to attract the required metal. These functionalized fibers can be placed directly into the

In addition to producing a range of catalysts developed in our own laboratories, Johnson Matthey can manufacture catalysts to customers’ chemical and physical specifications. Johnson Matthey works with customers to

process stream to remove the metal via an ion exchange process. Once recovery is complete, the Smopex® (with the metal attached to it) can simply be filtered off leaving a pure process liquor behind.

ensure that, from first samples to full plant production, the catalyst meets the customers’ performance

Smopex fibers are easy to handle and filter. They can

requirements. The customer benefits from Johnson

remove metal from both homogeneously and

Matthey’s experience in the development, scale–up and

heterogeneously catalyzed reactions, and selectively

manufacture of catalysts.

remove ionic and non-ionic precious metal complexes from both aqueous and organic solutions.

Johnson Matthey will develop catalysts and manufacturing methods with customers for supply into their own

The use of Smopex® allows recovery from liquors

processes, or with partners for supply to a third party.

containing low levels of precious metal even down to parts per billion (ppb) levels.

3.7 TECHNICAL SUPPORT FOR CATALYTIC PROCESSES Johnson Matthey technical support continues when the

Traditional Refining Quotation: From the composition of your residues,

process is in production. Full technical advice is available,

Johnson Matthey can identify the best route

supported by analytical services. This service can be used

for the residues in the refinery and quote in

to enhance the performance of catalytic processes. If, for

advance for all costs.

example, a catalyst is being poisoned in a process, Johnson Matthey can work to identify the mechanism of deactivation by characterizing the poisoned catalyst and

Shipping:

The ways in which the residues of different types of catalyst should be returned are

investigating potential solutions.


23

24


4. Chemistries 4.1

HYDROGENATION

4.1.1 Carbon–Carbon multiple bonds Alkynes and alkenes are readily hydrogenated to alkanes over supported catalysts with the following general order of activity

substituted double bonds. Asymmetric hydrogenations are possible using chiral ligands. (see section 4.13.1). Alkynes can be readily hydrogenated to alkenes or alkanes under mild conditions using Pt or Pd supported catalysts. Typical operating conditions are temperatures of 20 –100˚C and hydrogen pressures of 1–10 bar.

Pd > Rh > Pt >> Ru Palladium is the most selective metal for the conversion The ease of hydrogenation decreases with increasing

of alkynes to alkenes without further hydrogenation to

substitution at the double bond. In molecules containing

the corresponding alkane. Modifiers such as amines or

more than one double bond, the least hindered will be

sulfur-containing compounds can be added to the reaction

hydrogenated preferentially, and exocyclic double bonds

system to improve the selectivity to the alkene.

more easily hydrogenated than endocyclic double bonds.

Alternatively, Pd catalysts can be modified with a second metal such as Pb, Cu or Zn. The best known and most

A complication in the hydrogenation of alkenes can be

widely used catalyst of this type is Lindlar’s catalyst which

double bond migration and cis–trans isomerisation. The

is a mixed Pd/Pb catalyst on a calcium carbonate support.

tendency of the PGMs to promote these reactions is

Selectivity to the alkene can also be improved by limiting

generally in the order

the hydrogen availability.

Pd > Rh > Ru > Pt = Ir Hence platinum catalysts are useful when double bond migration is to be avoided. Homogeneous (Rh and Ir) catalysts are particularly useful for selective alkene hydrogenations. For example in the rhodium-catalyzed hydrogenation of carvone to dihydrocarvone:

O Br + B(OH) 2

Neither the carbon–carbon double bond in the ring nor the ketone function is hydrogenated. Similarly, in the manufacture of the pharmaceutical Ivermectin, only one of several carbon-carbon double bonds is hydrogenated in the presence of Wilkinson’s catalyst, Rh-100 RhCl(PPh3)3. Rh-100 is normally selective for the least substituted double bond. Arene, carboxylic acid, ester, amide, nitrile, ether, chloro, hydroxy, nitro and sulfur groups are all tolerated. Catalysts such as Ir-90 [Ir(COD)(py)PCy3]PF6, Ir-93 [IrCl(COD)]2, Rh-93 [RhCl(COD)]2 or Rh-97 [Rh(nbd)2]BF4 are used for hydrogenating highly 24


Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

-C≡C- → -CH2.CH2-

50–100

1–10

None or alcohols

Pd/C A402002-5, A405028-5, Pd/c A503023-5, A102023-5, Pd/c A470085-5, A470129-5

-C≡C- → -CH=CH-

5–50

1–3

Alcohols, acetic acid, ethyl acetate or vapor phase

Pd/C A102038-5, Ni A-5000d/C Ni/Mo A7063 Pd(S)/C A103038-5 Pd/CaCO3 A303060-5 Pd,Pb/CaCO3 A305060-5, A306060-5

-CH=CH- → -CH2.CH2-

5–100

3–10

None, alcohols, acetic acid or ethyl acetate

Pd/C A402002-5,A405028-5, Pd/c A503023-5, A102023-5, Pd/c A470085-5, A470129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5

Selective hydrogenation of least substituted alkene

25–75

1–5

Methanol, ethanol, acetone, THF or toluene

Rh-100 FibreCat® 2003, 2006

Hydrogenation of substituted double bonds

25–75

1–5

Dichloromethane, toluene or ethanol

Ir-90, Ir-93, Rh-93 or Rh-97

4.1.2 Aromatic ring compounds

For the hydrogenation of alkyl-substituted polycyclic aromatics Rh and Pt catalysts are generally less selective

The activity of the catalysts, both heterogeneous and

than Ru unless the aromatic ring is highly substituted.

homogeneous, for the hydrogenation of aromatic rings are Benzene is readily hydrogenated to cyclohexane.

in the order

Industrially this reaction is performed in the vapor phase Rh > Ru > Pt > Pd

with a Pt/alumina fixed bed catalyst.

The rate of hydrogenation of the aromatic ring with PGM

Partial hydrogenation of benzene to cyclohexene can be

catalysts varies with the nature, number and position of

effected at 25–200°C and 10–70 bar with a heterogeneous

the substituents.

Ru catalyst.

Typical operating conditions for heterogeneous Rh

Ru is often recommended if C–O or C–N bond

catalysts would be 20–60°C and 1–4 bar hydrogen

hydrogenolysis is to be avoided. Basic additives may be

pressure. In general, homogeneous catalysts offer no

used to suppress unwanted hydrogenolysis or coupling

advantages and are very rarely used for ring

reactions and to increase the hydrogenation rate.

hydrogenations. There is considerable interest in the ring hydrogenation of

Carbocycles Rhodium is the most active catalyst, but cost may count against its large scale use in some cases. Pt and Ru catalysts usually require more extreme operating conditions but the performance of Ru catalysts can often be improved by the addition of small amounts of water.


4-t-butylphenol to the cis-isomer (as opposed to the transisomer). Choice of a specific Rh/carbon catalyst together with the use of a non-polar solvent (e.g. hexane) can yield >90% of the desired cis-isomer. Increased solvent polarity (e.g. isopropanol) results in the production of increasing quantities of the trans product.

25

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Carbocyclic ring

5–150

3–50

None or alcohols

Rh/C C101023-5,C101038-5 Rh/AI2O3 C301011-5 Ru/C D101023-5,D101038-5, Rh/c D170201-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5 Pd/C A503023-5, A102023-5, Pd/c A102038-5, A470085-5 Ni A-5000

Phenol →Cyclohexanone

30–200

1–10

In summary, selectivity is affected by:• choice of catalyst (including bimetallics) • solvent polarity and pH • reaction conditions (temperature and pressure).

None

Pd/C A102023-5, A105023-5

Rh is the most active catalyst under mild conditions and is recommended when hydrogenolysis is to be avoided. Pd is an effective catalyst especially for the hydrogenation of acyl- or acyloxy- pyridines. Generally, Pd is the preferred catalyst for selective hydrogenation of nitrogen-containing heterocyclic rings in the presence of carbocylic rings.

A reaction of considerable commercial importance is the one step Pd-catalyzed conversion of phenol to cyclohexanone (a precursor of Nylon 6), with minimal over hydrogenation to cyclohexanol. This reaction can be performed in either the liquid or vapor phase at 30–200°C and 1–10 bar hydrogen pressure.

Heterocycles In general, heterocycles are easier to hydrogenate than carbocycles. Heterocyclic compounds such as pyridines, quinolines, isoquinolines, pyrroles, indoles, acridines and carbazoles can be hydrogenated over Pd,

Ru is an excellent catalyst at elevated temperatures and pressures where N–dealkylation or deamination is to be avoided.

Pt, Rh and Ru catalysts. Hydrogenation of furans and other oxygen-containing Acidic solvents, such as acetic acid, and aqueous HCl solutions are often used to facilitate hydrogenation. Pt catalysts have been successfully used in the

heterocycles becomes more complex due to hydrogenolysis and ring cleavage possibilities. Hydrogenolysis is generally promoted by high temperature and acidic solvents.

hydrogenation of many nitrogen containing heterocycles at 25–50°C and 3–4 bar hydrogen pressure, e.g.

Specific requirements should be examined on a case by case basis.

26


Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Pyridines

30-150

3-50

None or alcohols

Pt/C B102022-5, B103032-5, Pt/c B501032-5, B170147-5 Ni A-5000 Rh/C C101023-5, C101038-5

Furans

30-100

5-60

None, alcohol or water

Pd/C A503023-5, A102023-5 Pd/c A102038-5, A570147-5 Pd/c A570129-5 Rh/C C101023-5, C101038-5 Ru/C D101023-5, D101038-5

Pyrroles

30-100

3-50

Acetic acid or alcohol/acid

Pd/C A503023-5, A102023-5, Pd/c A570129-5 Pt/C B102022-5, B103032-5, Pt/c B501032-5, B170147-5 Rh/C C101023-5, C101038-5

1

4.1.3 Carbonyl compounds

Ether formation, which may occur as an alcohol dehydration product, can be reduced using a Ru catalyst.

Aldehydes

Pd is the preferred catalytic metal for the hydrogenation

In general, saturated aliphatic aldehydes can be

of aromatic aldehydes. Typical reaction conditions are

hydrogenated over Pt, Ru or Ir catalysts to the

5–100°C and 1–10 bar hydrogen pressure.

corresponding primary alcohols at 5–150°C and 1–10 bar hydrogen pressure. Pd tends to be an ineffective catalyst for aliphatic aldehydes but is the metal of choice for aromatic aldehydes.

Pd will also catalyze the production of hydrocarbon formed from the hydrogenolysis of the alcohol intermediate. Acidic conditions and polar solvents promote the formation of the hydrocarbon by-product.

Ru is the catalytic metal of choice for hydrogenation of aliphatic aldehydes. A well known example is the hydrogenation of glucose to sorbitol in aqueous solution. This reaction is traditionally performed industrially with a Ni catalyst, but there are advantages to be gained by using a Ru catalyst.

Although Pt and Ru can be considered for this application, there is the possibility of simultaneous ring hydrogenation. To some extent, this side reaction can be inhibited by the addition of either salts of Zn, Ag or Fe (typically <1 mol % with respect to the catalytic PGM) or low molecular weight aliphatic nitriles.

These are:In the special case of haloaromatic aldehydes to the • lower operating temperatures, hence less caramelization of the product

corresponding haloaromatic alcohols, Pt is the metal of choice. Extensive hydrodehalogenation will occur with Pd catalysts.

• lower operating pressures, hence lower plant capital costs • unlike Ni, Ru is not leached into the sugar solution so this particular product purification step/environmental hazard is eliminated.


27

Of particular interest is the selective reduction of α–ß

Pt/C is used commercially to produce cinnamyl alcohol from

unsaturated aldehydes such as crotonaldehyde and

cinnamaldehyde. Cinnamyl alcohol has also been produced

especially

cinnamaldehyde.2

in the laboratory from cinnamaldehyde using water soluble

A generalized reaction

scheme is shown above.

Ru and Ir homogeneous catalysts.

Carbonyl hydrogenation is generally less facile than olefins

Pd/C is used to produce dihydrocinnamaldehyde.

thus making selective hydrogenation of the α–ß unsaturated

Dihydrocinnamyl alcohol is the product when both reducible

aldehyde to the α–ß unsaturated alcohol quite difficult.

functions are hydrogenated.

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

to aliphatic alcohols

5–150

1–10

Alcohols, ethyl acetate

Ru/C D101023-5, D101038-5, Ru/c D170201-5

or water

Pt/C B103032-5, B103018-5, Pt/c B501032-5, B170147-5

to aromatic alcohols

5–100

1–10

Neutral: benzene, hexane, DMF or ethyl acetate

Pd/C A503023-5,A102023-5, Pd/c A470085-5, A570129-5 Pd/c A570201-5

RR’C=O →RR’CH2

5–100

1–10

Acidic: alcohol or acetic acid

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A470085-5 Pd/c A470129-5, A470201-5

Glucose → Sorbitol

100–120

20–30

Water

Ru/C D101023-5, D101038-5, Ru/c D170201-5

α,ß unsaturated aldehyde to unsaturated alcohol

50–120

5–15

Isopropanol

Pt/C B103032-5, B103018-5, Pt/c B501032-5, B170147-5

1 R.A. Sheldon and H. van Bekkum Fine Chemicals Through 1 Heterogeneous Catalysis Wiley – VCH 2001 363-369 2 P. Gallezot and D. Richard Catal Rev - Sci Eng (1998) 40 81-126 28


Ketones

The selective hydrogenation of an α–ß unsaturated ketone

Ketone hydrogenation is similar to that of aldehyde

to the corresponding α–ß unsaturated alcohol is much

hydrogenation, but is usually less facile due to increased steric hindrance at the carbonyl group. Saturated aliphatic

more difficult than is the case for the α–ß unsaturated aldehydes. However, hydrogenation of the α–ß unsaturated ketone to the saturated ketone is relatively

ketones can be hydrogenated over Pt or Ru to the

trivial with a Pd catalyst as would be expected.

corresponding secondary alcohol at 5–150˚C and 1–10 bar hydrogen pressure. Aromatic ketones are best

Ketones can be hydrogenated to alcohols using

hydrogenated over Pd catalysts.

homogeneous catalysts such as Ru–100. The reaction is

Ru is the catalytic metal of choice for the hydrogenation of water soluble ketones and for hydrogenations in alcohol

promoted by base. Homogeneous catalysts are particularly attractive for performing enantioselective hydrogenations on functionalized ketones.

solvents (since ether formation is minimized).

Please see section 4.13 for information on asymmetric

Aromatic ketones can be hydrogenated to the corresponding alcohol or alkyl aromatic (hydrogenolysis)

ketone reduction.

over a variety of catalysts. Hydrogenolysis is favored by acid conditions, elevated temperatures and polar solvents.

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

to aliphatic alcohols

5-150

1-10

Alcohols, ethyl acetate or water

Ru/C D101023-5, D101038-5, Ru/c D170201-5 Pt/C B103032-5, B103018-5, Pt/c B501032-5, B170147-5

to alcohols

15-100

1-50

Toluene, THF, methanol, ethanol or propan-2-ol

Ru-100

to aromatic alcohols

5-100

1-10

Neutral: benzene, hexane, DMF or ethyl acetate

Pd/C A503023-5, A102023-5, Pd/c A470085-5, A570129-5, Pd/c A570201-5

RR’C=O → RR’CH2

5-100

1-10

Acidic: alcohol or acetic acid

Pd/C A503023-5,A503038-5, Pd/c A102023-5,A470085-5, Pd/c A470129-5, A470201-5


29

4.1.4 Nitro and nitroso compounds

p–Amino phenols can be obtained in good yield by the hydrogenation of aromatic nitrobenzenes in dilute sulfuric

Aromatic nitro and nitroso groups are hydrogenated to the

acid under carefully controlled conditions. The yield is

corresponding amine over palladium and platinum

usually improved by the presence of a water soluble

catalysts. The analogous aliphatic compounds are less

quaternary ammonium compound.

easily hydrogenated as the resulting amine tends to inhibit the catalyst. In this case, higher catalyst loadings and

Hydrogenation of nitro compounds is a very

more vigorous reaction conditions are required. To some

exothermic reaction

extent the inhibiting effect can be decreased by operating

RNO2 + 3H2 ➝ RNH2 + 2H2O ΔH = –431 kJ/mole

under acidic conditions. Nitro/nitroso hydrogenations are usually performed with heterogeneous catalysts.

It is therefore often desirable to use a solvent as a heat sink.

Intermediate hydroxylamines, oximes, azo compounds or

Although it is possible to hydrogenate a dinitroaromatic to

p–aminophenol can be obtained depending upon the

a nitroaminoaromatic, such reactions are generally difficult.

reaction conditions.

It has been reported1 that this reaction can be achieved using the Ru-100, RuC12(PPh3)3 homogenous catalyst. Pd–111, [Pd(OAc)2]3 and Rh–120, [RhCl2Cp*]2 have been used for the hydrogenation of nitro and nitroso compounds

Reaction pathways for the hydrogenation of the nitro group

1 J.F. Knifton J. Org. Chem. (1975) 40 519 30


Reaction

Temperature (°C)

Pressure (bar)

From Nitro Compounds to aromatic amine

5-50

1-5

to aliphatic amine

50-150

3-25

Solvent*

Neutral or acidic alcohols, ethyl acetate

Alcohols. Base causes inhibition. Acid sometimes improves activity

Catalyst

Pd/C A401102-5, A405028-5, Pd/c A503023-5, A503032-5, Pd/c A102023-5, A470085-5, Pd/c A470129-5, A470201-5 Ni A-5000 Pt/C B103032-5, B501032-5, Pt/c B170147-5 Pd/C A401102-5, A405028-5, Pd/c A503023-5, A503032-5, Pd/c A102023-5, A470085-5, Pd/c A470129-5, A470201-5 Ni/Mo A-7000 Ni/Mo A-7063 Pt/C B103032-5, B501032-5, Pt/c B170147-5 Rh/C C101023-5

to haloamines

90-150

8-12

Alcohols, ethyl acetate

Pt/C Pt/c Pt/c Pt/c

B101032-3, B103032-3, B170147-3, B102032-1, B101038-1, B105047-1, B170147-1

to p-aminophenols

50-150

<1

Dilute H2SO4

Pt/C B102032-1, B105047-1, Pt/c B170058-1

From Nitroso Compounds to aromatic amine

5-100

1-10

Neutral or acidic alcohols, ethyl acetate

Pd/C A503023-5, A503032-5, Pd/c A505085-5, A102023-5, Pd/c B570147-5, A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5

to aliphatic amine

5-100

1-10

Alcohol/HCl or acetic acid

Pd/C A503023-5, A503032-5, Pd/c A505085-5, A102023-5, Pd/c A570147-5, A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5

* Many processes are operated commercially without solvent, using molten substrate at temperatures higher than those indicated above

4.1.5 Halonitroaromatics

I > Br > Cl > F

The hydrogenation of halonitroaromatics to the

and its position on the aromatic ring with respect to the

corresponding haloaminoaromatic is a reaction of

nitro group being hydrogenated:-

considerable industrial importance. Traditionally, Fe/HCl catalyst has been used to obtain the desired yield of the haloamine (Béchamp Process) but it is increasingly being replaced by Pt catalysts because of several

ortho > para > meta Acidity in the form of acid addition or an acidic catalyst will tend to inhibit hydrodehalogenation.

inherent disadvantages:Typical operating conditions are 90–150°C and 8–12 bar • a steam distillation step is needed to separate the product haloamine from the iron oxide sludge –

hydrogen pressure, as more severe conditions promote hydrodehalogenation.

an operation which is energy intensive and therefore expensive

The reaction can be effectively carried out with or without the use of a solvent. A solvent, while facilitating

• environmental problems with the disposal of the iron sludge. These problems can be successfully overcome using a Pt supported catalyst; Pd catalysts cause high levels of hydrodehalogenation. The ease of halogen removal (as the

temperature control (acting as a heat sink for the exotherm) may have a marked influence on the rate and selectivity to the haloamine. Generally, aprotic solvents inhibit hydrodehalogenation whereas protic solvents tend to increase reaction rates.

hydrohalic acid) depends on the particular halogen:© 2008 Johnson Matthey Plc

31

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Halonitro → haloamine

90-150

8-12

Alcohols or cyclohexane

Pt/C B101032-3, B103032-3, Pt/c B102032-1, B101038-1, Pt/c B105047-1, B170147-1 Pt/c

4.1.6 Reductive Alkylation

R1 R

NH2

+

O

C

R

N

C

2

R

R1 R2

+

H2O

Pt H2 or Pd R1 R NH CH R2 Reductive alkylation involves the reaction of a primary or

In some cases, the amine may be produced in situ from

secondary amine with an aldehyde or ketone to form a

the corresponding nitro or nitroso compound. Similarly the

secondary or tertiary amine respectively.

carbonyl may, in some circumstances, be produced in situ from the appropriate acetal, ketal, phenol or alcohol.

Formation of the imine intermediate is favored by acidic conditions. The imine intermediate is seldom isolated in

Aldehydes are generally more reactive than ketones

such cases.

because they tend to be less sterically hindered. Pt or Pd catalysts are preferred for reductive alkylations. Typical

The amines formed are also suitable substrates for further

reaction conditions are 50–300°C and 1–50 bar pressure.

alkylation. A catalyst of high selectivity is required to minimize Thus, when wanting to produce a secondary amine (with a

hydrogenation of the carbonyl compound to the alcohol

minimum of tertiary amine) from a primary amine

prior to imine formation via condensation. Sulfided

feedstock, the primary amine to carbonyl molar ratio

platinum catalysts can be used to minimize alcohol

should not exceed one.

formation but generally require more severe operating conditions. Non-sulfided Pt catalysts are effective under mild reaction conditions (10 bar, 100°C).

R NH CH

32

R2

R1

R1

R1

+

O

+ H2

C R2

R

N CH

+ H2O

R2 2


CH3 NH

NH2

CH CH2

+

CH3

C

O

CH3

NH

CH2

NH CH

CH

CH3 CH3

CH3 The manufacture of the rubber antioxidant 6-PPD

A reductive alkylation of commercial significance in the

Typical operating conditions are 25–50°C and 1–80 bar

rubber chemicals industry is the reaction of

pressure. A wide variety of solvents can be used – such as

4–aminodiphenylamine with MIBK (methyl isobutylketone)

dichloromethane, alcohol, toluene and tetrahydrofuran

to produce 6PPD.

(THF).

Homogeneous Ir catalysts (exemplified by Ir–93,

For example N–cyclohexylaniline can be formed in 98%

[IrCl(COD)]2 plus ligand) are effective for reductive

yield at atmospheric pressure in methanol.

alkylations (as well as imine hydrogenations – see section 4.1.8).

Ir O

+ H2N

+ H2

N H

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

from aldehyde

20–100

1–50

Alcohol or the aldehyde

Pd/C A109047-5, A503032-5, Pd/c A503023-5, A102023-5, Pd/c B570147-5, A570129-5 Ni A-5000 Ni/Mo A-7000 Pt/C B102032-3, B104032-3, Pt/c B170147-3, B105032-3, Pt/c B106032-3, B171147-3

from ketone

50–150

1–50

Alcohol or the ketone

Pd/C A109047-5, A503032-5 Pd/c A503023-5, A102023-5, Pd/c B570147-5, A570129-5 Ni A-5000 Ni/Mo A-7000 Pt/C B102032-3, B104032-3, Pt/c B170147-3, B105032-3, Pt/c B106032-3, B171147-3


33

4.1.7 Reductive Aminations

R1

R1 C

O

+

NH3

R2

R2

Pd

R1 R2

C

N

H

+

H2O

H2

CH NH2

This reaction is essentially the same as a reductive alkylation except that the “amine” feedstock employed is ammonia. The catalyst of choice is almost invariably Pd. Excess ammonia is employed to suppress hydrogenation of the carbonyl to the corresponding alcohol.

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

from aldehyde

50–300

1–50

None or alcohol


from ketone

50–300

10–50

None or alcohol


4.1.8 Imines Me

Reductive alkylations/aminations involve the condensation of a carbonyl compound with an amine to form an imine

Me

Me N

HN

intermediate, which undergoes hydrogenation to the

HN

+

amine. In some cases, the imine is the feedstock for hydrogenation. Pd and Pt heterogeneous catalysts are

Ph

Ph

Ph

typically used although homogeneous Ir catalysts are also effective, particularly for enantioselective hydrogenations. Pd and Pt catalysts can be used under relatively mild operating conditions of 20–100°C and 1–10 bar pressure. Alcohols are usually the solvents of choice and acidic conditions often promote the reaction.

34


Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Imine → amine

20–100

1–10

Alcohol or toluene

Pd/C A109047-5, A503023-5, Pd/c A503032-5, A102023-5, Pd/c A570147-5, A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5

4.1.9 Nitriles

In neutral media, Pd is also effective for the production of tertiary amines.

Hydrogenation of nitriles can be carried out over Rh, Pt or Pd catalysts at 5–150°C and 1–100 bar hydrogen pressure.

For aliphatic nitriles, with proper selection of conditions,

Primary, secondary or tertiary amines can be formed via

either Rh, Pt or Pd may be effective for the formation of

the intermediate imine

primary amines, whereas Rh catalysts yield secondary amines as the predominant product and Pt or Pd catalysts RCH2NH2

favor the formation of tertiary amines – especially in the hydrogenation of short chain aliphatic nitriles.

R

C

N

RCH

NH

(RCH2)2NH Dinitriles, either aliphatic or aromatic, usually need (RCH2)3N

considerably higher operating pressures (100–220 bar) to effect the hydrogenation.

For example, veratrylnitrile can be readily hydrogenated to the corresponding primary amine with a Pd catalyst

In acidic aqueous media, nitriles can undergo reductive hydrolysis to aldehydes and/or alcohols by hydrolysis of

at 10–50°C and 3–5 bar

the imine intermediate.

CH3O

CN

CH3O

CH2 NH2

Pd CH3O

H 2O R

C

N

R CH

NH

RCHO

+

NH3

CH3O

Pd is the catalyst of choice for this reaction which can be For the formation of the primary amines, either acidic solvent conditions (at least 2–3 moles of acid/mole of nitrile) or excess ammonia (>2 moles/mole nitrile) are required. Formation of secondary amines is facilitated by neutral conditions while tertiary amines are usually produced predominantly only in the presence of a low molecular weight secondary amine. For aromatic nitriles in ammonia or acidic media, Pd and Pt are preferred for the production of primary amines. Pt and Rh are preferred for the formation of secondary amines in neutral solvents.

effected at 30–100°C and 1–5 bar. The aqueous solvent is made acidic with H2SO4, HCl or CH3COOH. The acid promotes the hydrolysis of the imine and acts as a scavenger for the ammonia. In order to force the reaction to the desired aldehyde, phenylhydrazine or semicarbazide can be added. The aldehyde forms the respective condensation phenylhydrazone or semicarbazone product. At least 1–2 moles of additive/mole of aldehyde needs to be added. Reductive cyclization may also be an important reaction pathway when a suitable second reactive functional group is available.


35

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

5–100

1–10

Alcohol/ammonia or alcohol/min. acid or acetic anhydride

Pd/C A503023-5, A503032-5, Pd/c A102023-5, A570147-5, Pd/c A570129-5

to Aliphatic Amine 1°–amine RNH2

Pt/C B103032-5, B501032-5, Pt/c B570147-5 Rh/C C101023-5, C101038-5 Ni A4000, A5000, Ni A7000, A7063 AMCAT 5 AMCAT 7 2°–amine R2NH

50–100

2–5

Alcohols. neutral conditions

Rh/C C101023-5, C101038-5 Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5

3°–amine R3N

50–100

2–5

Alcohols, or DMF with 2°–amine

Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5

to Aromatic Amine 1°–amine ArNH2

50–100

1–10

Alcohol/ammonia or alcohol/min. acid or acetic anhydride


2°–amine Ar2NH

5–100

2–5

Alcohol/water

Pt/C B103032-5, B501032-5, Pt/c B170147-5

3°–amine Ar3N

50-100

2–5

Alcohol or DMF with 2°–amine


to Aldehyde 30–100

36

1–5

Alcohol/acid or water/acid

Pd/C A402002-5, A109047-5, Pd/c A503023-5, A570129-5 Pd/c A570201-5


4.1.10 Oximes

Rh is also the catalyst of choice if reductive coupling is to

Hydrogenation of oximes can give rise to primary,

solvents favor the formation of primary amines by

secondary or tertiary amines, hydroxylamines or imines.

suppressing reductive coupling side reactions. Acidic

The imines are rarely isolated as such, since condensation

conditions are recommended to minimize reaction rate

coupling can readily occur as well as the possibility of

inhibition caused by the amine products. With a Rh

reductive hydrolysis to the aldehyde.

catalyst, the amount of acid is not critical, but with a Pd

be minimized. Acidic (H3PO4 or H2SO4) or ammoniacal

catalyst, there should be at least 2–3 moles of acid per Acetylation of the oxime facilitates hydrogenation.

mole of oxime.

Rh is the preferred catalytic metal for the formation of

Pt or Pd catalysts are generally preferred for the partial

primary amines usually producing less secondary amine

hydrogenation of oximes to the corresponding

product than Pd.

hydroxylamine (or imine precursor).

+

RCH2NH2 RCH

N

OH

H2O

RCH2NHOH

RCH

RCHO

NH

+

+

H2O

NH3

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

oxime → amine

30–60

1–5

Alcohol/acid

Pd/C A109047-5, A503023-5, Pd/c A503032-5, A102023-5, Pd/c A570147-5, A570129-5 Rh/C C101023-5, C101038-5


37

4.1.11 Hydrogenolysis

(b) N–Debenzylation

Debenzylations

For N–debenzylations exemplified by the general scheme

Benzyl groups and related structures (e.g. carbobenzyloxy) are often used to protect amine and hydroxyl functional

CH2NR1R2

CH3

Pd

+

R1R2NH

groups. Catalytic hydrogenolysis for the removal of these protecting groups occurs under mild conditions. Typical operating conditions are 5–100°C and 1–10 bar hydrogen pressure.

both reduced and unreduced Pd/C can be effective.

Hydrogenolysis is promoted by high temperatures and low

Acidic solvents such as acetic acid, ketones with acid

pressures. In most cases Pd/carbon is the catalyst of

addition, or even acid buffered solvents are desirable to

choice, but there are differences between O–debenzylation

prevent inhibition of the catalyst by the amine products.

(cleavage of carbon–oxygen bonds) and N–debenzylation

The amine adsorption characteristics are pH dependent.

(cleavage of carbon–nitrogen bonds).

Typically, N-debenzylations are more difficult to perform than O-debenzylations. The slower N-debenzylation reaction rate can often be improved by using higher

(a) O–Debenzylation

palladium content in the catalysis design. The classical Pd/C catalyst used for this reaction is Pearlman’s catalyst (a 20% palladium hydroxide on carbon

(c) Removal of Carbobenzyloxy Group

catalyst), but in most cases it is possible to use a catalyst with a much lower Pd content. Best results are invariably

In practical terms, operating conditions are very similar to

obtained with an unreduced (oxidic) Pd/carbon catalyst.

those of N–debenzylation described above.

The best solvent for this reaction is THF (tetrahydrofuran)

Acidic conditions are desirable, not only to avoid amine

although acetic acid or alcohol have also been used

inhibition of the catalyst, but also to avoid poisoning by the

successfully.

liberated CO2.

CH2 CH2OR

OCONR1R2

CH3

CH3

Pd

+

+ R1R2NH + CO2 ROH

Pd

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Debenzylation

5–100

1–10

Alcohols, THF, acetic acid or alcohol/mineral acid

Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10,

Pd/c A470129-10

38

Carbon–oxygen cleavage

50–150

3–50

Alcohol/mineral acid, THF or acetic acid

Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10, A401002-20, Pd/c A470129-20

Carbon–nitrogen cleavage

50–150

3–50

Alcohol/mineral acid or acetic acid

Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10


Hydrodehalogenations

Rosenmund Reductions

Hydrodehalogenation occurs under relatively mild

The Rosenmund Reduction is the Pd catalyzed hydrogenation

conditions (5–100°C and 1–10 bar) but is favored by

of an acyl chloride to the corresponding aldehyde

increasing temperature rather than pressure. RX + H2 ➝ RH + HX COCl

X = F, Cl, Br, I Pd is the most active and preferred catalytic metal. The

CHO

Pd

+ R

HCl

R

ease of hydrogenolysis is in the order I > Br > Cl > F

The classical catalyst for this reaction is Pd/BaSO4, but in most cases Pd/carbon powders can be substituted with

Selective hydrodehalogenation is possible in some cases

advantage.

e.g. removal of chlorine (as HCl) with fluorine retention. This is demonstrated by the fixed bed vapor phase

The operating conditions must be mild (temperatures of

conversion of CFC (chlorofluorocarbon) to HFC

5–50°C and pressures of 1–3 bar), otherwise over-

(hydrofluorocarbon).

hydrogenation to the primary alcohol will occur. In order to preserve the selectivity to the aldehyde, nitrogen or sulfur-containing compounds are often added to modify the catalyst. Typical additives include thiourea or thioquinanthrene. These well-defined compounds have largely eclipsed the use of the variable “quinoline/sulfur” reagent. The reaction

The reaction rate also depends on molecular structure and

must be carried out in the absence of water, otherwise

neighboring functional groups. Cleavage of aryl halides is

hydrolysis of the feedstock to the corresponding carboxylic

more facile than alkyl halides.

acid will occur. Dry powder Pd/C catalyst must therefore be used (as opposed to water-wet pastes) to maintain the

The reaction rate is often adversely affected by the release

anhydrous conditions.

of halide ion, therefore an addition of basic halide acceptors is often made. Typical additives include aliphatic

As with other hydrodechlorinations, a basic chloride

amines (e.g. triethylamine), sodium carbonate, magnesium

acceptor is often utilized. Examples include 1,2-butylene

oxide etc. At least 2 equivalents of base per equivalent of

oxide, aliphatic amines, sodium carbonate, magnesium

halide should be added. Suitable choice of solvent can also

oxide, 2,6–dimethylpyridine etc. (again at least 2

help minimize the effect of catalyst inhibition by halide.

equivalents per equivalent of halide).

Alcohols or esters (such as ethyl acetate) can be used

Sometimes, due to the ease of acid chloride

as solvents, often with the addition of up to about 10%

hydrodechlorinations, it is possible to remove the liberated

water, which can help to maintain catalyst activity.

HCl with a nitrogen sparge or by operating at subatmospheric pressures so that the addition of specific chloride acceptors is not necessary.


39

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Hydrodehalogenation

5–100

1–10

Alcohols, ethyl acetate or vapor phase

Pd/C A402002-5, A405028-5 Pd/c A503023-5, A503038-5, Pd/c A102023-5, A570129-5, Pd/c A570201-5

Rosenmund Reduction (acyl chloride → aldehyde)

5–50

1–3

Toluene, xylene, acetone or THF

Pd/C A302023-5, A302038-5, Pd/c A701023-5 Pd/BaSO4 A308053-5, A201053-5, A201053-10

4.1.12 Transfer Hydrogenations1

Transfer hydrogenation can be accomplished using homogeneous catalysts. For example, tetralone has been

When hydrogen gas and/or hydrogenation plant is not

hydrogenated with Rh-120 with an amine ligand in the

readily available, then the hydrogenation may be achieved

presence of a hydrogen donor, propan-2-ol.

using a chemical hydrogen donor. In effect the catalyst dehydrogenates the donor molecule to generate hydrogen to carry out the hydrogenation. The donor molecule and catalyst should be selected with care so that the rate of hydrogen release is comparable to the rate of hydrogenation of the feedstock. Typical donor molecules include cyclohexene, formates, phosphinates, propan–2–ol and indolene.

Examples of PGM precursors of homogeneous catalysts used for transfer hydrogenations in the literature are Iridium (Ir-93 [IrCl(COD)]2), Rhodium (Rh-93 [RhCl(COD)]2), (Rh-120 [RhCl2(CP*)]2) and Ruthenium (Ru-120 [RuCl2(pcymene)]2). Please refer to section 4.13 for information on asymmetric hydrogenation.

Pd and Pt are the heterogeneous catalysts of choice. Transfer hydrogenations are often performed under reflux but it is possible to operate at lower temperatures when required. Different selectivities are sometimes achieved by transfer hydrogenation rather than H2 gas.

O

OH

+

(CH3)2CHOH

+

(CH3)2CO

1 R.A.W. Johnstone et al. Chem. Rev. (1985) 85 129–170 40


Reactant

Product

Donor

Solvent

Temperature

Catalyst

Nitro

Amine

Formic acid, phosphinic acid, sodium formate, sodium phosphinate, tetraethyl ammonium formate

Methanol, ethanol or THF

50–80

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5

Halonitro

Haloamine

Formic acid, phosphinic acid, sodium phosphite

Methanol, ethanol or water

60–80

Pt/C B101032-3, B103032-3, Pt/c B170147-3, B102032-1, Pt/c B101038-1, B105047-1, Pt/c B170147-1

Imine

Amine

Formic acid & Et3N, propan–2–ol

None or acetonitrile

0–60

Ir–93 Rh–93, Rh–120

Alkene

Alkane

Cyclohexene, indolene, triethyl ammonium formate

None

Reflux

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5

Carbonyl

Alcohol

Cyclohexene, phosphinic acid, sodium phosphinate

Ethanol or THF

Reflux

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5

Ketone

Alcohol

Formic acid & Et3N, propan–2–ol

None or acetonitrile

0–60

Ir–93 Rh–93, Rh–120

Formic acid, sodium formate

Ethanol, methanol or THF

50–80

Pd/C A503023-5, A503032-5, Pd/c A470129-5, A402028-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10

Debenzylation

4.2 DEHYDROGENATION Dehydrogenation is an endothermic process, and hence high operating temperatures (up to 250°C) and high catalyst loadings (3–10% with respect to feedstock) are often necessary. At such high temperatures, most PGM complexes decompose, so homogeneously catalyzed dehydrogenations in the liquid phase are usually not feasible. Traditionally, nitrogen has been used to purge the liberated

(˚C)

Hydrogen Acceptor

Product

Nitrotoluene

Toluidine (+ water)

Nitrobenzene

Aniline (+ water)

Maleic acid

Succinic acid

Dimethylmaleate

Dimethylsuccinate

α–methylstyrene

Cumene

trans–stilbene

Dibenzyl

Tetralin

Decalin

Indene

Indane

hydrogen from the reaction, but increasingly the use of hydrogen acceptors is finding favor.


41

Hydrogen acceptors should be used in 0.5–2.0 molar

Very small additions (2–10 ppm with respect to the

quantities with respect to the liberated hydrogen. Where

feedstock) of organic sulfur compounds such as diphenyl

the products include water, care should be taken, because

sulfide can promote some dehydrogenation reactions.

the steam which is liberated can cause bumping of the

Such additions have to be very carefully optimized.

reactor contents in liquid phase reactions. A particular dehydrogenation of industrial importance is For the same reason it is desirable to use dry powder

the formation of iminostilbene from iminodibenzyl

catalysts for liquid phase reactions and dry pelleted catalysts for gas phase reactions. Pd/C

It is highly desirable to use a hydrogen acceptor if at all possible, thus permitting lower temperature operation than

nitrotoluene

N H

N H

would be possible without a hydrogen acceptor. The operating temperature should be as low as possible,

The product is an intermediate in the preparation of

consistent with acceptable product yields in order to

Carbamazepine – a treatment for epilepsy.

minimize:• metal crystallite sintering – see section 2.1.7

For the dehydrogenation of cyclohexanols and cyclohexanones, the favored hydrogen acceptors are

• product decomposition and/or by–product formation

olefins e.g. α−methylstyrene.

Typical high boiling point solvents used include biphenyl and polyglycol ethers. It is possible sometimes to use the OH

hydrogen acceptor as the solvent.

Pd/C

The ease of dehydrogenation is dependent on the substrate and operating conditions. However, the following general comments can be made:-

OH

R

α-methyl styrene R

• easier if at least one double bond is close to the dehydrogenation site A common problem with operating catalysts at high • easier if the end product is a fully aromatic compound

that coking may occur (see section 2.1.7). This has the

• 6 and 7-membered or larger ring systems are easier to dehydrogenate than 5-membered

temperatures in the vapor phase for extended periods is

rings1.

effect of masking individual metal crystallites. One way of reducing this effect on the Pd or Pt pelleted catalysts is to introduce a small quantity of hydrogen into the feedstock.

The catalysts of choice for liquid phase dehydrogenations are Pd > Pt > Rh Catalyst performance can be enhanced by the addition of inorganic bases such as Na2CO3, MgO (up to about 5% by weight with respect to the catalyst). Addition of base neutralizes any acidic sites on the catalyst, which if left untreated, could cause by–product formation.

1 M. Bartok Stereochemistry of Heterogeneous Metal Catalysis 1 Wiley Interscience (1985) 35–37 42


Reaction

Temperature (°C)

Solvent

H2 Acceptor

Catalyst

Cyclohexanones/anols to Phenols

180–275

biphenyl

Olefinic (e.g. α−methylstyrene, tetralin)

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5, A501023-10, Pd/c A501038-10, A101023-10, Pd/c A101038-10

Alkane to Alkene

180–250

Glycol, PEG

Nitrotoluene, nitrobenzene

Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5, A501023-10, Pd/c A501038-10, A101023-10, Pd/c A101038-10

Alcohol to Carbonyl

>200

None (vapor phase)

None

Pt/C B103032-5, B103018-5, Pt/c B501032-5 Ni/Mo A-7000 Ni/Mo A-7200

4.3 HYDROFORMYLATION

The butyraldehyde is either reduced directly to n-butanol, or

Hydroformylation is the largest and oldest homogeneously

reduced to 2-ethylhexanol – a well known plasticizer alcohol.

catalyzed industrial process, in which the simultaneous

For terminal alkene hydroformylation, the Rh

addition of one mole of CO and H2 is made across a

homogeneous catalyst is used together with a large

carbon–carbon double bond to produce an aldehyde.

excess (50-100 x molar with respect to the catalyst) of a

aldolized and dehydrated to 2-ethylhexenal and then

tertiary phosphine such as triphenylphosphine. Many Industrially, the most important alkene feedstock is propene.

different Rh catalysts (or precursors) can be used. Typical Rh compounds include Rh-40 Rh(PPh3)2(CO)Cl, Rh-42

CH 3 +

CO +

CHO +

H2

straight chain

CHO

RhH(CO)(PPh3)3, Rh-43 Rh(acac)(CO)(PPh3) and Rh-50 Rh(acac)(CO)2.

branched chain

Provided the Rh compound selected can enter into the The original cobalt-catalyzed high pressure process was

catalytic cycle, the precise form of the precursor is of little

discovered in Germany over 60 years ago. The replacement

importance. The factors affecting the choice of a particular

of Co by Rh in the mid 1960’s provided a major

precursor usually involves such “practical” properties as:-

breakthrough in the history of homogeneous catalysts. The main advantages are:-

• absence of halogen (important for long term stability in steel reactors – but not in glass equipment)

• higher straight chain: branched chain product ratios (the straight chain product usually being the more

• ease of storage/handling in air

commercially desirable)

• minimal health hazards

• lower operating pressures, hence lower plant

• solubility in the reaction medium

capital costs • cost of conversion of the Rh metal to the • lower operating temperatures, hence less

particular complex

formation of oligomeric by-products • lower feedstock consumption per tonne of product, hence increased yield

The propene hydroformylation process operated by Hoechst (Ruhrchemie) is interesting in that the reaction medium is a two phase aqueous/organic system in which

These more than compensate for the higher cost of Rh.

the Rh catalyst is solubilized in the aqueous phase using a sodium sulfonate substituted triphenylphosphine as the

A consortium of three companies (Davy McKee/Johnson

ligand. Since the Rh is confined to the aqueous phase,

Matthey/Union Carbide) commercialized the Rh catalyzed

product/catalyst separation is straightforward with minimal

process, now known as the L.P. (Low Pressure) Oxo

loss of Rh into the organic phase.

Process and licensed it world-wide. Well over 1 million tonnes of n–butanol is now made annually from propene using the L.P. Oxo Process.


43

RhH(CO)L3 L

C3H7CHO

CH2

CHCH3

RhH(CO)L2 H L2Rh H

H

O C

L2Rh CO

C3H7

CHCH3 CH2

CO

H2 O L2Rh

C

CH2CH2CH3 C3H7

L2Rh

CO

CO

L2Rh

CO C3H7

CO CO The catalytic cycle for the rhodium catalyzed hydroformylation of propene (L = triphenylphosphine)

There have been many studies of the mechanism of

The vast majority of (and certainly all of the industrially

hydroformylation. Suitable choice of operating conditions

important) processes use Rh as the catalytic metal of

and ligand can drive the reaction to form the straight chain

choice. The literature indicates that Pt has some activity as

aldehyde, or the branched chain product. Thus the tailor-

a hydroformylation catalyst, often used together with a

making of ligands to favor the formation of a particular

SnCl2 promoter.

product has become a practical proposition. For example, Union Carbide has developed a phosphite ligand to give very high straight chain to branched chain ratios. Other industrial processes incorporating a Rh catalyzed hydroformylation step include:• production of vitamin A The BASF process involves the hydroformylation of a terminal alkene, whereas the Hoffmann–La Roche process hydroformylates an internal alkene • production of 1,4-butanediol The Kuraray process (operated by Lyondell) involves the hydroformylation of allyl alcohol

44


Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Hydroformylation

50–150

10–50

Toluene or ethyl acetate

Rh–40, Rh–42, Rh–43, Rh–50, Rh–112 Rh 2–ethylhexanoate

4.4 CARBONYLATION

Methyl methacrylate can thus be obtained from the

The carbonylation of methanol to acetic acid is one of the

thereby avoiding the classical cyanohydrin route.

carbonylation of methyl acetylene in a methanol solvent,

largest industrial processes using homogeneous catalysis. By analogy, when water is used as the solvent, acids are formed (hydrocarboxylation). For example one step in a DuPont/DSM route to adipic acid involves the Rh/I CH3OH +

CO

CH3COOH

hydrocarboxylation of butadiene with an Ir catalyst.

Ir

+ CO

+

H2O

COOH

HOOC

The original process, developed by Monsanto and subsequently purchased by BP, used an iodide-promoted Rh catalyst. More recent work by BP Chemicals has

Under different conditions, Shell and others have shown

shown that an iodide-promoted Ir homogeneous catalyst

that polyketones can be formed from the carbonylation of

(Cativa™ process) can be used with

advantage.1

Over 60%

alkenes in the presence of cationic Pd complexes derived

of the world’s acetic acid is now made by methanol

from palladium acetate or PdCl2.2 Chelating diphosphines,

carbonylation.

such as diphenylphosphinopropane or 1,1’-bis(diphenylphosphino)ferrocene have been shown to be very effective

Pd is the catalytic metal of choice for the carbonylation of

ligands for this type of reaction.

alkynes and alkenes. In alcohol solvents esters are formed. O CH2

CH

CR

+ CO

+ R’OH

CH2

C

COOR’

CH2

+

CO n

O

O

n

R CH2

CHR +

CO

+ R’OH

RCH2CH2COOR’

These polymers find use as engineering thermoplastics.

1 J.H. Jones Platinum Metals Rev. (2000) 44(3) 94 2 E. Drent and P.H.M. Budzelaar Chem. Rev. (1996) 96 663


45

Pd is also the catalyst of choice for the base-catalyzed hydrocarboxylation of aryl or benzyl halides. Base acts as a scavenger for the liberated HX.

ArX

+

CO

+

H2O

+

ArCOOH

HX

(X = halide) ®

Anchored homogeneous catalysts (FibreCat ) are under development for carbonylation reactions (see section 2.3).

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Alkene, alkyne or secondary alcohol carbonylation

50–150

10–50

Toluene or alcohol

Pd–62, Pd–100, Pd–103, Pd–111, PdCl2

Primary alcohol carbonylation

25–200

1–50

None

Rh–110, Rh–112, RhCl3.xH2O, RhI3

4.5 DECARBONYLATION

The decarbonylation reaction can be used to advantage in

Both Pd and Rh catalysts have been used to decarbonylate

one–step synthesis of arabinitol from glucose.

classical carbohydrate chemistry, exemplified by the

aldehydes (to produce alkanes) and acyl chlorides (to produce chloroalkanes or chloroarenes).

CHO H HO

RCOX

RX

+

CO

(X = H, Cl)

H H

CH2OH

OH H

HO

OH

H

OH

H

H

Glucose

CO

OH CH2OH

CH2OH

There are also reports of the effective decarbonylation of

+

OH

Arabinitol

carboxylic anhydrides, ketones and ketenes. Dihydrocinnamaldehyde can be decarbonylated with Rh

Yields of 90% can be achieved with Rh-100 in

(Rh–40 [RhCl(CO)(PPh3)2] or Rh–100 [RhCl(PPh3)3]) to form

N–methylpyrrolidone at 130°C in 30 minutes.2

ethylbenzene1

in 96% yield.

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Decarbonylation of aldehydes, acyl chlorides, carboxylic acid anhydrides, ketones and ketenes

110–145

1

N–methylpyrrolidone, toluene, benzonitrile or xylene

Rh–100, Rh–40, Rh–93 + chelating diphosphine

1 J.M. O’Connor and J. Ma J. Org. Chem. (1992) 57 5075 2 M.A. Andrews and S.A. Klaeren Chem. Comm. (1988) 1266 46


4.6 HYDROSILYLATION

Rh catalysts can selectively hydrosilylate alkynes to the

Hydrosilylation (often referred to as hydrosilation) is the

solvent used.2

alkene, but the regiochemistry is very dependent on the

addition of an H–Si bond across a carbon-carbon double bond. RC

CH

+

Et3SiH

Rh-100

SiEt3

R H

CH2

CHR’

+

R3SiH

R3Si

R

H

H

SiEt3

+ H cis

CH2CH2R’

trans

The reaction finds practical application in the “curing” or hardening of silicone polymers effected by the cross

Solvent

% cis

% trans

others

Benzene

86

12

2

Acetonitrile

3

95

2

coupling of different silicone fragments.

O

R

R’

+

Si O

H

CH2

O Si CH O

O

R Si

O

CH2

R’

O Si CH2 O

Platinum compounds are extremely active catalysts for

Rh catalysts can also catalyze some hydrosilylation

this reaction.1 The catalyst can be used at such low levels

reactions that cannot be catalyzed by Pt complexes3. Rh

that it is not necessary to separate it from the silicone

catalysts have also been used to prepare chiral silanes.4

product. Originally, chloroplatinic acid (Speier’s catalyst) was used as the most readily available and cheapest hydrosilylation catalyst. However there are two problems:• chloroplatinic acid is a potent sensitizer and hazardous to health, so great care must be taken during its handling • chloroplatinic acid contains platinum in oxidation state IV which must be reduced to Pt(0) before it becomes catalytically active. This results in a variable induction period. A more reliable/reproducible catalyst is Karstedt’s catalyst which is made from chloroplatinic acid by the addition of an appropriate siloxane and reducing agent. The Pt is in the Pt(0) oxidation state when used. Johnson Matthey supplies a variety of custom Karstedt’s catalyst. In some cases, specific Pt(II) precursors are used rather than Karstedt’s catalyst. Compounds which have been used in this way include Pt-92 [PtCl2(cyclohexene)]2, Pt-96 [PtCl2(COD)] and Pt-112 [PtCl2(SEt2)2]. Although homogeneous catalysts are commonly used, heterogeneous Pt/C catalysts are effective in some cases.

1 L.N. Lewis et al. Platinum Metals Rev. (1997) 41 6 2 R. Takenchi and N. Tanonchi J. Chem. Soc. Perkin Trans. (1994) 2909 3 A.G. Bessmertnykh et al. J. Org. Chem. (1997) 62 6069 4 K. Tamao et al. J. Am. Chem. Soc. (1996) 118 12469


47

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Hydrosilylation of alkenes

25–75

1

None or hydrocarbons

Chloroplatinic acid, Pt–92, Pt–96, Pt–112, Pt–114, Pt/AI2O3 B301013-5, B301099-5

Hydrosilylation of alkyne to cis-alkene

25

1

Ethanol or propan-2-ol

Rh–93, Rh–100

Hydrosilylation of alkyne to trans-alkene

25

1

Acetonitrile

Rh–93 + PPh3 or Rh–100

4.7 CROSS-COUPLING REACTIONS

The ease of C-X bond cleavage is in the order I > Br > Cl.

Cross-coupling reactions are among the most important

The relative reactivities of Ar-X can be correlated to their

chemical processes in the fine chemical and

respective bond dissociation energy:

pharmaceutical industries. These reactions represent the key steps in building complex molecules from simple

Ph-Cl: 96 kcal/mol

precursors. Recently, there has been a burgeoning of

Ph-Br: 81 kcal/mol

interests in this area, mainly due to interest in coupling

Ph-I:

65 kcal/mol

challenging substrates, such as electron rich aryl chlorides, triflates, nitriles, etc. Steric effect as well as the presence

In some cases, the iodide system is active enough for

of sulfur on the substrate can play an adverse role in

coupling to occur in the absence of a ligand. Typically, a

coupling reactions. One of the key mechanistic steps in

Ph3P-based Pd complex is suited for Ar-Br coupling, while

coupling reactions is the oxidative addition of the aryl

Ar-Cl coupling is practically impossible, although there has

halide, Ar-X to Pd(0) (see below).

been some success with activated aryl chlorides. Electron withdrawing substituents on the Ar ring activates the Ar-X

reductive elimination Ar-R

LnPd

oxidative addition

0

bond, while electron donating groups have a deactivation

ArX

effect on the Ar-X bond. During the late 1990’s several academic groups (eg: Koie,

Ar

LnPd

LnPd

Fu, Buchwald, Hartwig, Beller, etc.) found that electron-

X

R M B Sn Si Zn Mg

Ar

rich phosphines (aliphatic) in the presence of a Pd precursor favor the Ar-Cl addition to Pd(0). The bulkiness of the ligand (cone angle measures bulkiness) is also

transmetallation MX

important, as it facilitates the reductive elimination step. In this regard, t-Bu3P acts as an excellent electron rich, bulky

MR

General Mechanism of Coupling

oxidative addition

LnPd 0

base-HX

ArX base LnPd

H LnPd

X β- hydrogen elimination R

Ar X

R

Ar R

LnPd

H X

Ar Mechanism of Heck Coupling

Mehanism of Heck Coupling

48


P(t-Bu)2

monodentate ligand. However, t-Bu3P is a pyrophoric waxy solid and therefore difficult to handle in a conventional production environment.

Fe

Ph

Our research indicates that bidentate ligands are equally

Ph

effective in coupling chemistry. It is well documented that the large bite angle of a bidentate ligand enhances the

Ph

reductive elimination step. From a handling perspective, a

Ph

fully formed, relatively air-stable yet active catalyst is a

Ph

preferred choice.

Q-Phos Johnson Matthey offers advanced technology for coupling reactions. Several examples of these electron rich bulky

These catalysts have been successfully scaled up and tested in commercial processes.

monodentate and bidentate phosphine based “third generation” catalysts are given below.

4.7.1 Heck Reaction A Japanese scientist, Mizoroki (1971) and an American scientist, Heck (1972) developed independently a protocol to couple an aryl or alkenyl halide with an olefin in the

P

Pd

P

presence of a Pd based catalyst. These reactions can occur both inter- and intra-molecularly.

The application of

this chemistry includes the synthesis of hydrocarbons,

Pd(t-Bu 3 P)2

conducting polymers, light emitting electrodes, dyes and enantioselective synthesis of natural products. An

Pd-116

example of classical Heck reaction is demonstrated for the synthesis of anti-inflammatory agent- LTD4 antagonists1,2.

Br Pd

P

O

P

Pd

CO2 Me

Br + Cl

3 mol% Pd(OAc) 2 9 mol% P(o -Tol) 3 Et 3 N / DMF / 100°C / 1.5 hr (91%)

N

Br [Pd(μ-Br)t-Bu3P]2

Cl

Pd-113

N

O

>95% trans -isomer

Me Cl

Cl

P

P

Cl

P

Pd

Fe

Pd Cl

CO 2Me

CO 2 Me

L-699,392 (Merck-Frosst)

These reactions are promoted by a base, which neutralizes Cl

P

N

CO 2 H

the liberated acid. Pd(0), stabilized with an aromatic phosphine ligand, is the active catalytic species (LnPd) and the favored reaction media are dipolar aprotic solvents such as acetonitrile, DMF, DMSO and DMA.

di-t-bpfPdCl2

Pd-118

FibreCat 1032

Recently Heck coupling has been applied to challenging substrates with the aid of the next generation catalysts. An example of such reaction for the synthesis of an API intermediate (actual substrate is disguised) is demonstrated below, where Pd(0) catalyst, Pd(t-Bu3P)2 is the best catalyst of choice. 1 V. Snieckus, Cross Coupling Strategies and methods in Aromatic and Heteroaromatic Synthesis (Scientific Update Course), New Orleans, November 12-14, 2002 2 A.O. King et.al. (Merck), J. Org. Chem., 1993, 58, 3731-3735


49

R'' Cl

For challenging aryl chloride conversions several of Johnson Matthey’s third generation catalysts, including

R

R

Pd-cat +

R''

Pd-116, Pd-118 and Pd 119, provide significant advantages.

DMF/ 120 oC/Et3N

R

R

The di-tert-butylphosphinoferrocene palladium dichloride (Pd-118) is an air stable, yet highly active catalyst, which

Pd-catalyst

Conversion

Selectivity

Pd(Ph3P)2Cl2

0

-

Pd(OAc)2/TPP

0

-

has been proven to be effective in Suzuki coupling. The following table illustrates the generality of the catalyst in Suzuki coupling towards a wide variety of substrates.3

Pd(t-Bu3P)2

100

95

Pd2dba3/(o-tolyl)3P

95

2.5

Pd(PPh3)4

0

-

Pd(PCy3)2Cl2

0

-

Pd2dba3/t-Bu3P

100

82

ArX

Pd(0) (t-Bu3P)2 can be also used for indole and azaindole syntheses by direct annulation.1 In the following example, enamine formation followed by intra molecular Heck coupling of an aryl chloride is speculated, rather than alpha ketone arylation followed by enamine.

R1

R4

R4

Cl

Pd(t-Bu 3P)2 , K 3PO4

+ O

NH

HOAc, MgSO4, DMA

R3

R1

R3

N

R2

+

Pd-118/ 120oC

PhB(OH)2

Ar-Ph

K2CO3/DMF

Entry Substrate

Catalyst loading

yield (%)

1 2

4-chlorotoluene 4-bromoanisole

0.01 equiv 0.01 equiv

98 100

3 4

4-chloroanisole 4-bromo-3-methylanisole

0.01 equiv 0.01 equiv

100 96

5 6 7

2-chlorothiophene 2-bromo-4-fluoroanisole 2-chloro-4-fluoroanisole

0.01 equiv 0.01 equiv 0.01 equiv

84 95 95

8

2-chloro-3-methylpyridine

0.01 equiv

89

9

2-chloro-4, 6-dimethoxytriazine Bromomesitylene

0.01 equiv

100

0.01equiv

85

R2

10

4.7.2 Suzuki-Miyaura Coupling For moderately challenging substrates, such as Currently, Suzuki coupling is the most widely utilized Pd

bromothiophenes, chloropyridines, etc., the polymer

catalyzed coupling reaction in the Pharmaceutical and Fine

supported Pd catalyst, FibreCat 1032 has shown good

Chemical industries. The coupling reaction involves the

results. Following our preliminary report4, additional

reaction of a substituted aryl boronic acid (nucleophile)

research from Abbott Laboratories 5, indicates that these

with a substituted aryl halide, diazonium salt or triflate

are practical catalysts for conventional and microwave

(electrophile) to produce biaryls. In general, Suzuki

assisted Suzuki coupling. An example of the microwave

coupling reactions require milder conditions than the Heck

assisted Suzuki coupling reaction is given below.

reactions and are favored due to the non toxicity of the boron reagents. B(OH)2

Commercial examples include antihypertensive drug Valsartan (Novartis) and the fungicide Boscalid

3 % FibreCat 1032

+

K 2 CO3, EtOH, MW

(BASF)2.

N

Cl

N

Me Me

O N N

Yield: 89% (100%)

Cl

COOH O NH

N N

NH N

Valsartan (Novartis)

Cl Boscalid (BASF)

1 Nazare, et.al., Angew. Chem. Int. Ed., 2004, 43, 4526-4528. 2 Rouhi, Chemical and Engineering News, 2004, 82, 49-58 3 Colacot & Shea, Org. Lett., 2004, 21, 3731. 50

4 Colacot et. al., Organometallics, 2002, 21, 3301. 5 Sauer et.al., Org. Lett., 2004, 6, 2793.


4.7.3 Alpha-ketone Arylation Alpha-ketone arylation is a relatively new type of carboncarbon coupling reaction, where an aryl halide is added to the alpha position of a carbonyl group by activating the

Simple Pd(0) compounds such as Pd-101 Pd(PPh3)4 or

CH. Early studies indicate that catalyst choice is critical in

catalysts made from precursors such as Pd-111

accomplishing this type of coupling. Initial results show

[Pd(OAc)2]3, Pd-110 [Pd(allyl)Cl]2 and Pd-94 Pd2(dba)3 with

that Pd-118 is a very good catalyst for such

suitable phosphine ligands can also be used, depending on the substrate.

transformations. An example is given below. X

X +

Ar-X

4.7.5 Organometallic Reactions

di-tbpfPdCl 2 alcoxide base Toluene

Ar O

O

Yield 70-95%

4.7.4 Carbon-heteroatom Coupling – e.g. Buchwald-Hartwig Amination Carbon–heteroatom coupling can be effected by a Pd-

In some reactions, a prerequisite is the production of an organometallic intermediate containing metals such as magnesium, tin, zinc or lithium. These organometallic compounds can react with an aryl halide with the elimination of the metal halide and the subsequent formation of a coupled product. The best known general example of this type of reaction is probably the Grignard reaction.

catalyzed reaction. This can include forming C-N, C-O, C-S ArX + Ar1MgX

and C-P bonds. The C-N bond forming process (amination)

Ar

Ar1

+ MgX2

is often referred to as the Buchwald–Hartwig, although initial work was carried out by Koie and co workers in

In some cases these reactions proceed satisfactorily.

Japan.

However, in other cases, the presence of a homogeneous

A general scheme of amination and ether formation is shown below. As there is an acid by-product, a base is

palladium catalyst may dramatically improve the yield of the coupled product.

used, often a strong organic base such as NaOtBu to drive

The relative positions of the substituents on the aromatic

the reaction.

rings determine the point at which coupling occurs, i.e. Br MgBr

Pd

+ MgBr2

+ R

R

Heterocyclic ring coupling is also possible, e.g. A wide variety of homogeneous Pd(0) catalysts can be used for the above reactions.

CH3

CH3

Br ZnCl

Pd

+ ZnClBr

+

The new range of highly active Pd-catalysts are very

S

S

suitable for this difficult coupling reaction. Pd-113 and Pd-

The organometallic reagent may in some cases be

116 have been shown to catalyze a wide range of

completely aliphatic, but coupling can still occur, e.g.

substrates including aryl chlorides and triflates. Air stable catalysts such as Pd-118 (Pd(dtbpf)Cl2) and Pd-107 (Pd(dppf)Cl2) show good activity for aryl chlorides and

CH2Br

Pd

CH2CH

CH2

+ Bu3SnBr

+ CH2 CHSnBu3

bromides, respectively.

Bu = butyl

The following example show the fast rates achieved with

Palladium-catalyzed reactions of this type, involving the

Pd-113 (strong base)6 and the stable turnover available

use of tin-based reagents, are often referred to as Stille

with Pd-116 (cheaper base)7.

coupling reactions. Similar reactions involving zinc-based reagents are referred to as Negishi couplings.

6 J. Hartwig et al, Angew. Chem. Int. Ed., 2002, 41, 4746 7 J. Hartwig et al, J. Org. Chem., 2002, 67, 6479


51

4.7.6 Sonogashira Reaction

The generic structure of such species is

X = halide, acetate L = P or N

Palladium catalysts can also be employed in the coupling of terminal alkynes with aryl or alkyl halides. The reaction,

C

known as the Sonogashira reaction, generally involves the

L

X Pd

use of a palladium catalyst in conjunction with copper iodide, the copper reacting with the alkyne to form an

Pd X

L

C

alkynylcuprate. Mild conditions are usually used for this reaction, often

Many of these complexes show not only increased activity

room temperature, allowing a large number of functional

over the more traditional catalysts, but also exhibit very

groups to be tolerated.

good thermal and air stability. In the case of the phosphite catalysts developed by Bedford1 (see below) these reactions can be performed in air without the drying of

R

Pd/CuI X +

R

R’

R’

base

solvents or reagents – a major advance over the more conventional catalysts.

about the double bond is usually preserved, making this

Their main advantage is activity – catalyst loadings as low as 10-4 mol % have been successfully used in reactions of

an extremely useful reaction for the synthesis of ene-yne

aryl bromides.

If the reaction is performed on an alkene, the geometry

molecules with specific geometry.

The Bedford bridging chloro palladacycle containing the tris (2,4-di-t-butyl phenyl) phosphite ligand – Pd 109.

R' X

Pd/CuI

+

t-Bu

R' base

R

R

ArO O

4.7.7 Palladacycles

OAr P

Cl

t-Bu

Cl

The use and versatility of coupling reactions has increased

t-Bu

Pd

Pd

O

P ArO

OAr

recently with the advent of new Pd catalysts known as palladacycles.

t-Bu

Reaction

Temperature (°C)

Solvent

Catalyst

Heck

25–100

Various (e.g. toluene, THF)

Pd–62, Pd–100, Pd–101, Pd–106, Pd–108, Pd–109, Pd–111, Pd-116, Pd-119 FibreCat®–1001, 1002 Pd/C A109047-5, A405028-5, A503023-5, A102023-5, A470085-5

Suzuki

25–100

Various

Pd–101, Pd–109, Pd–111, Pd-113 Pd-118 FibreCat®–1001, 1002, 1032

Buchwald–Hartwig

80–100

THF or toluene

Pd–106, Pd–107, Pd–113 Pd–111, Pd–116, Pd–118 FibreCat®–1001, 1002

Organometallic reactions

25–100

THF, dioxane, toluene or DMF

Pd-62, Pd-100, Pd–101, Pd-103, Pd-106

Sonogashira reaction

25–120

THF or DMF

Pd-100, Pd-101 FibreCat® 1032

1 D.A. Aldisson, R.B. Bedford, S.E. Lawrence and P.N. Scully 2 Chem. Comm. (1998) 2095 52


One of the best known applications is in the synthesis of

4.8 CYCLOPROPANATION AND

chiral methylphenidate. The racemic form of

CARBENE REACTIONS

methylphenidate is sold as Ritalin™, widely prescribed for

The generation of carbenes from the decomposition of

the treatment of hyperactive children. However, the

diazo compounds can be catalyzed by metal complexes.

d-threo isomer is 13 times more active than its mirror

The carbene binds to the metal and can subsequently be

image.2

transferred to an alkene (cyclopropanation), to an alkyne

Dirhodium(II) tetrakis[methyl-2-pyrrolidone 5(S) carboxylate] Rh2(5S-MEPY)4

(cyclopropenation) or even inserted into a C–H bond depending on the choice of catalyst, substrate and conditions. RCH

CHR + CR1R2N2

RCH

CHR

+

N2

C

CH3OOC

N

R2

R1

N Rh

Rh RC

CR

1 2

+ CR R N2

RC

CR

+

N2

C R1

N

O

CH3OOC

COOCH 3

O

O

N

O

COOCH3

R2

The original catalysts were based on Cu complexes, but more recent work has involved the use of Rh catalysts. For non-stereoselective cyclopropanations or

The process involves a highly selective intermolecular

cyclopropenations, the catalysts of choice are based on

asymmetric insertion at the α position of N–Boc piperidine with methyl phenyldiazoacetate followed by removal of the

dimeric Rh(II) carboxylates e.g. Rh-110 [Rh(OAc)2]2

Boc protecting group. Pd catalysts such as Pd-111 [Pd(OAc)2]3 have been used, but their application seems to be restricted to reactions

O

involving terminal olefins and α,β unsaturated carbonyls.

OCH3 N2

O

NBoc

It is in the area of enantioselectivity that the Rh(II)

OCH3

Rh2(5S-MEPY)4

carboxamidate1 complexes really demonstrate their

Cyclohexane/ 500C/ 4h

NBoc

effectiveness. These catalysts are characterized by four bridging amide

69%

HCl

ligands bound to the di–rhodium core, with two oxygens and two nitrogens bonded to each Rh atom, and each pair

O

of nitrogen atoms adjacent to one another.

OCH3 NH.HCl

d-threo-methylphenidate

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Carbene insertion into terminal alkene or α,β unsaturated carbonyl

0-10

1

Ether or dichloromethane

Pd–70, Pd–111

Cyclopropanation, cyclopropenation, carbene insertions

0–50

1

Cyclohexane, pentane or dichloromethane

Rh–110, Rh–115

1 M.P. Doyle and D.C. Forbes Chem. Rev. (1998) 98 911-935 2 T. Colacot Proc. Indian Acad. Sci. (Chem. Sci.) (2000) 112 197


53

4.9 ISOMERIZATION

Olefin isomerization processes can also be catalyzed by Pd

Isomerization of olefins can be carried out effectively using

application because of their stability to air and moisture.

homogeneous catalysts. Wilkinson’s catalyst (Rh-100

Here the trans-isomer is favored kinetically as well as

RhCl(PPh3)3) has been used in the synthesis of several

thermodynamically.

or Ru. The Pd(II) catalysts are well suited for industrial

natural products and can be used in the isomerization of

Pd

allyl alcohols to enols.

OH

1-pentene

Rh CH3

trans-2-pentene

OH Heterogeneous catalysts are also effective for olefin isomerization, with Pd/C being the best when used under acidic conditions at elevated temperatures. Rearrangements can also be performed with Pd catalysts. Optically active cyanohydrin can be stereoselectively isomerized to the α,β–unsaturated nitrile1 in 89% ee using Pd-62 PdCl2(CH3CN)2. OAc

OAc PdCl2(CH3CN)2 C5H11

Reaction Allylic rearrangements

Temperature

Pressure

(°C)

(bar)

25–90

1

* CN

83% yield

C5H11

*

Solvent

Catalyst

THF, xylene, benzene or no solvent

Pd–111 + PPh3, Pd–101, Pd–62 Pd/C A109047-5, A503023-5, Pd/c A503038-5, A570147-5, Pd/c A570129-5 Rh–100, RhCl3.xH2O

CN

1 H. Abe, H. Nitta, A. Mori and S. Inoue Chem. Lett. (1992) 2443 54


4.10 OLIGOMERIZATION AND POLYMERIZATION Rh, Pd and Ru are the main metals used in PGM-catalyzed polymerization reactions. Low molecular weight oligomers These catalysts were first developed by Grubbs2 in

can be produced and are dependent on the type of

1993. Tricyclohexylphosphine is the preferred ligand as

catalyst used.

bulky groups make the catalyst more active. These catalysts are active without rigorous exclusion of water CH2

C CH2 allene

or oxygen, and are more tolerant of functional groups than Zeigler–Natta catalysts. Rh

Rh PPh3 CH2

CH2

CH2

ROMP reactions with norbornene derivatives can be catalyzed by vinylidine Ru complexes.3 These carbene

CH2

complexes can be prepared from Ru-100 RuCl2(PPh3)3 by reaction with terminal alkynes followed by phosphine

CH2 CH2

CH2

CH2

ligand exchange.

Polyketones can be made by the Pd-catalyzed

Cl

copolymerization of carbon monoxide and an olefin

Cl

(ethylene or propylene). The Pd(II) catalyst is made from

PCy3 Ru

palladium acetate or palladium chloride and a diphosphine ligand.1

C

PCy3

Bu H

Similar Ru(II) carbene catalysts can be prepared from

Polymerization of simple alkenes such as polyethylene is normally carried out using Ziegler–Natta catalysts (W, Ti, Ni). However, recent advances in Ru carbene chemistry

Ru–120 [RuCI2(p–cymene)]2 without using phosphine ligands. These catalysts enable high stereoregularity in the polymerization of substituted norbornadienes.

have lead to new interest in PGM-catalyzed polymerization. Ring Opening Metathesis Polymerization (ROMP) can be efficiently catalyzed by Ru carbene complexes of the type shown.

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Polymerization

25–100

1–10

Alcohols, toluene, biphasic systems (water/hexanol), or no solvent

Ru–100, RuCl3.xH2O + ligand, Ru–120 + ligand, Pd–101, Pd–111 + PPh3, RhCl3.xH2O, Rh–100

Copolymerization

25–150

1–150

CH2Cl2 or methanol

Pd–62, Pd–101, Pd–111 or PdCl2 + ligand

Telomerization

25–80

1

Acetonitrile or methanol

Pd–101, Pd–111 + PPh3 + nucleophile

1 K. Nozaki, N. Sato and H. Takaya J. Am. Chem. Soc. (1995) 117 9911 2 S.T. Nguyen, R.H. Grubbs and J.W. Ziller J. Am. Chem. Soc. (1993) 115 9858 3 H. Kitayama and F. Ozaura Chem. Lett. (1998) 67


55

4.11

In contrast to hydrogenation systems, sulfur-containing

SELECTIVE OXIDATION

moieties do not appear to poison PGM catalysts under

Supported PGMs are very good oxidation catalysts and

oxidation conditions.

this property is used to effect the total oxidation of For example, 2-thienylmethanol can be readily oxidized to

pollutants to CO2 , H2O and N2 in industrial fume abatement and automotive anti–pollution applications.

the corresponding aldehyde in >90% yield with a Pt/C catalyst in toluene. Furthermore, the catalyst can be reused quite effectively.

Pt catalysts are used for the oxidation of the fuel (hydrogen, lower aliphatic alcohols and some other fuels)

1/

in fuel cells and other electrochemical devices. S

2

O2

+ H 2O

CH 2OH

CHO

S

In order to effect selective oxidations, it is necessary to operate under relatively mild conditions to minimize CO2 formation; typically 20–60°C and up to 5 bar air pressure. If flammable solvents are required then low O2 concentrations (typically 3%O2 or 5%O2 in N2) can be used as a safe replacement for air. The longer reaction times can be compensated for by increasing the pressure within the reactor. Johnson Matthey has also shown that H2O2 (typically 30%) is an effective oxidant. The PGM catalysts will rapidly decompose H2O2, therefore efficient use requires a continuous feed over the course of

4.11.1(b) Secondary Alcohol to Ketone For aliphatic alcohols, Pt-Bi catalysts exhibit the highest activity. The Pt-Bi catalysts can be run under neutral or basic conditions. For example, 2-octanol can be readily oxidized to the corresponding ketone in >90% yield with Pt-Bi/C in water with 0.5 molar equivalent of NaOH added. The catalyst can be used for at least three reaction cycles with negligible loss in activity.

reaction. When using H2O2 as oxidant it must be noted

OH

O

that water by-product is also being introduced, the presence of which can enhance the selectivity to the

1/

carboxylic acid.

2

O2

+ H 2O

For aromatic alcohols the mixed metal catalyst Pd-Pt-Bi/C has shown the highest activity followed by Pd/C and Ru/C.

4.11.1(a) Primary Alcohol to Aldehyde

These catalysts require the presence of base (as with primary aromatic alcohol oxidation).

The selective oxidation of primary alcohols to the aldehyde functionality can be performed in the liquid phase. For

The selective oxidation of secondary alcohols can be

aliphatic alcohols the Bi-promoted Pt catalysts have shown

conducted in the presence of water, such that H2O2 is a

the highest activity. Ru/C is more aldehyde-selective but

suitable oxidant in these reactions.

higher catalyst loadings are required to attain desirable conversions.

4.11.1(c) Primary Alcohol or Aldehyde to Carboxylic Acid

Selectivity to the aldehyde is enhanced by the use of organic solvents which are immiscible with water, e.g. toluene, xylene, dichloroethane etc. For example, geraniol

The selective oxidation of primary alcohols and aldehydes

can be converted to citral in toluene or xylene solvent at

to the carboxylic acid functionality can be achieved using

60ºC and 3 bar air using Pt-Bi/C, Pt/C or Ru/C catalysts.

Bi-promoted Pt catalysts and trimetallic Pd-Pt-Bi/C. Under neutral conditions Pt-Bi/C can give high carboxylic acid yields, whereas Pt-Pd-Bi/C catalyst requires basic

OH + 1/ 2 O 2

O

conditions to attain high activity (which can also lead to + H 2O

the formation of condensation by-products). Water is a good solvent for this reaction due its promotional effect on

For aromatic alcohols the Pd-Pt-Bi/C, Pd/C and Ru/C

the oxidation of aldehyde to carboxylic acid.

catalysts all display high activity under basic conditions. These conditions can be achieved by running the reaction in the presence of base such as an aqueous solution of NaOH or NaHCO3. 56


Pd-Pt-Bi/C has been used in aqueous solutions at 40–60ºC

• careful control of the oxygen availability (often achieved

for the air oxidation of sugars to the corresponding mono-

by operating the reaction with partial oxygen pressures

acid, e.g. glucose ➝ gluconic acid. The reaction is favoured

as low as 10 mbar)

by alkaline conditions, typically pH 8–10. • pH optimization Premature poisoning of the Pt catalyst can occur by complete coverage of the surface by oxygen to form a Pt

• periodic regeneration of the catalyst by a washing/reduction treatment

oxide species. This effect can be minimized by: Reaction

Temperature (ºC)

Pressure (bar)

Solvent

Catalyst

Primary Alcohol to Aldehyde

30-60

1-3

Toluene, xylene, acetonitrile

Pt/C B103032-5, B103018-5 B501032-5, B101002-5, B112002-5, B170201-5 Ru/C D101023-5, D101038-5 D170201-5, D103002-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5 FibreCat® 3002

Secondary Alcohol to Ketone

30-80

1-3

Water, water + base, toluene, stylene acetonitrile

Pt/C B103032-5, B103018-5 B501032-5, B101002-5, B112002-5, B170201-5 Ru/C D101023-5, D101038-5 D170201-5, D103002-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5 FibreCat® 3002

Alcohol or Aldehyde to Acid

30-60

1-2

Water, water + base

Pt/C B103032-5, B103018-5 B501032-5, B101002-5 B112002-5, B170201-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5

Glucose to Gluconic Acid

40-50

1

Water + base

Pt/C B103032-5, B103018-5 B501032-5, B101002-5 B112002-5, B170201-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5

4.11.2 Dihydroxylation of Alkenes

Osmium tetroxide is extremely hazardous and great care must be exercised when using this reagent.

The cis-dihydroxylation of alkenes has been traditionally catalyzed by osmium tetroxide in combination with a

There are two user-friendly alternatives to using the

variety of co-oxidants including hydrogen peroxide, sodium

tetroxide. The first consists of osmium tetroxide anchored

hypochlorite, air (oxygen), N-methylmorpholine-N-oxide and

onto a polymeric support (FibreCat 3003). Supporting the

t-butylhydroperoxide.

osmium in this manner renders it non-volatile and nonhazardous.

RCH

CHR'

+ 1/2O2 + H2O

Os

R

H

H

C

C

R'

OH OH


57

Reaction

Temperature (°C)

Pressure (bar)

Solvent

Catalyst

Dihydroxylation

0–50 0-60

ca 1 ca 1

t–Butanol, water or THF t–Butanol/Water

OsO4 or K2[OsO2(OH)4] FibreCat™ 3003

This material is best used in conjunction with Nmethylmorpholine-N-oxide and at temperatures of 60°C or

CH2

+ CH3CHO + Pd(0) + 2H

CH2 + Pd(II) + H2O

less which ensures that minimal levels (<5%) of the metal

The process was rendered catalytic and commercialized by

leaches from the support. Supporting the osmium in this

Wacker Chemie. The role of the Cu is to reoxidize the

manner also allows it to be easily removed from the

Pd(0) back to Pd(II).

reaction and allows for its possible reuse. The other alternative is “potassium osmate dihydrate” (dipotassium trans-dioxotetra(hydroxo)osmium (VI)). This

Pd(0)

+

2Cu(I)

+

Pd (II) +

2Cu(II) 2H+

+

2Cu(II)

2

+

2Cu(I)

H2O

can be used as an air-stable user-friendly source of

There are several versions of this process, both single and

homogeneous osmium for dihydroxylations in aqueous

two stage. Some are based on Pd/Cu/Cl and some are

solvents.

halide free.

4.11.3 Oxygen Insertion Reactions

Ruthenium tetroxide, although not available commercially, can be generated in situ from a suitable Ru precursor such

Over 85% of the world’s acetaldehyde is made by the

as RuCl3.xH2O and one of the oxidizing agents included in

selective oxidation of ethene with a mixed Pd/Cu

section 4.11.2. Ruthenium tetroxide is considerably more

homogeneous catalyst.

reactive than osmium tetroxide and is capable of oxidatively cleaving alkenes to form carboxylic acids.

Pd/Cu CH2

CH2

+

CH3CHO

2

’RuO4’

The fact that Pd salts can oxidize ethene to acetaldehyde stoichiometrically, has been known for over 100 years.

Reaction

C8H17CH

CHC7H14COOH

+ 2O2

C8H17COOH

Temperature (°C)

Pressure (bar)

Solvent

CH2=CH2 → CH3CHO

20–50

1–5

Acetic acid or alcohol

Pd–111, PdCl2 + Cu2+

Oxidative olefin cleavage

25–70

1

Various

Ru-100, RuCl3

4.11.4 Acetoxylation

+

HOOCC7H14COOH

pelargonic acid

oleic acid

azelaic acid

Catalyst recommended catalyst type shown in parenthese

The acetoxylation step was originally researched with a homogeneous Pd catalyst, but commercially a Te-modified

A key step in the Mitsubishi process for the production of

Pd heterogeneous catalyst is used to obtain a higher

1,4-butanediol from butadiene involves a Pd-catalyzed

selectivity to 1,4-diacetoxybutene and easier

acetoxylation step.

product/metal separation.

+

CH3COOH

+

2

CH3COO

HO 58

OOCCH3

OH

+

+

H2O

2CH3COOH


4.12 PARTICULATE CATALYSTS

The catalytic metal may be deposited on the outer

Particulate catalysts are used in fixed-bed continuous gas

deposition) or may be homogeneously impregnated

phase or liquid phase reactions.

throughout the bulk of the support (uniform deposition).

surface of the shaped particulate support (eggshell

For most purposes, the diffusion of reactants into the The dimensions of the catalyst bed (area of cross section

particulate bulk is slow, so eggshell catalytic metal

and length), reactor design, and size and shape of the

loading is generally preferred.

individual particulate (sphere, cylindrical tablet, ring, extrudate etc) are dictated by the requirements of heat

Catalytic metal loadings on particulate supports are usually

transfer, fluid flow and pressure drop in the system.

in the range 0.2-2% by weight with respect to the weight of support (as opposed to 1-10% for powdered catalysts).

For liquid phase reactions, the reactant, dissolved in a suitable solvent if necessary, is pumped into the column

Care should be exercised when charging particulate

packed with catalyst. The reactant gas, usually hydrogen

catalysts to fixed bed reactors to minimize physical

(or air-oxygen) can be passed co-currently or counter-

damage and the generation of fines with increased

currently through the catalyst bed. The product is collected

pressure drop and metal loss consequences. Details of

continuously from the catalyst bed and no filtration of

catalyst loading procedures are given in Section 2.1.3.

catalyst is involved. For gas phase reactions, only If catalyst to be used for a hydrogenation is supplied in an

co-current flow is possible.

unreduced form, it needs to be activated in the reactor Since the formation of fine particles by attrition must be

before use according to the following procedure:

kept to a minimum, high mechanical strength is a fundamental requirement of all particulate catalysts.

(i) load the catalyst carefully into the reactor and flush away air with flowing nitrogen (or other inert gas) at

The most commonly used particulate support in the fine

ambient temperature. (Ensure the volume of nitrogen

chemicals industry is γ-alumina. Although not as strong as

exceeds 5 x the volume of the reactor.)

α-alumina, the relatively high surface area (100–350 m2g-1) makes γ-alumina a more useful catalyst support than

(ii) introduce hydrogen at a concentration of 1% into the

α-alumina (typical surface area 1–10 m2g-1).

flowing nitrogen. Check for an exotherm in the

In some continuous gas phase reactions, the catalyst may

increase the temperature (over 60 minutes) up to the

become deactivated due to the deposition of coke on the

desired reaction temperature. The low hydrogen

active sites. In such cases the catalyst can be regenerated

concentration will prevent a large exotherm when the

in situ by the controlled oxidation of the deposited material

catalyst species undergoes reduction.

catalyst bed. If it does not exceed 20˚C, then slowly

(to CO2 and H2O). However, great care must be taken to avoid excessive exotherm generation in the bed to prevent irreversible metal crystallite sintering with subsequent loss of catalyst activity.

(iii) check for any exotherm and gradually increase the hydrogen concentration to 100% hydrogen. (iv) slowly introduce the feed to minimize any exotherms

Although not as strong as alumina, carbon can be used as a granular support in fixed bed reactors. It is used in cases where the aggressive/corrosive nature of the reactants makes the use of γ-alumina impossible, e.g.

until the desired feed rate is achieved. When the catalyst is finally discharged from the reactor, the above sequence should be reversed. It is very important to ensure that all traces of H2 are removed and that the catalyst has fully cooled to ambient temperature

Cl2CHCOOH


ClCH2COOH

+ HCl

before exposure to air.

59

4.12.1 Organic Synthesis Like their powdered catalyst counterparts, particulate PGM

Typical applications using Johnson Matthey particulate

catalysts are used for a variety of reactions including

catalysts for organic synthesis are shown below.

hydrogenation, amination, dehydrogenation, hydrodehalogenation and isomerization. Applications For Johnson Matthey Particulate Catalysts in Organic Synthesis

60

Catalyst Type

Support Material

Nominal Size/Shape

PGM

Loading (%wt)

Applications

47

Carbon

2–5mm Granules

Pd

0.5, 1.0

Hydrogenation of Olefins

48

Alumina

3mm Tablets

Pd

0.5

Hydrogenation/Dehydrogenation

49

Alumina

3mm Tablets

Pd

2

Hydrodehalogenation

50

Alumina

3mm Tablets

Pd

0.5


50A

Alumina

4–8mm Spheres

Pd

0.5


50B

Alumina

2–4mm Spheres

Pd

0.5


54

Alumina

3mm Tablets

Pd

0.5

Hydrogenation of Phenol to Cyclohexanone Amination of Ketones Hydrogenation of Olefins Aromatic Ring Hydrogenation

86

Carbon

3mm Extrudate

Pd

0.8

Hydrogenation of Alkynes and Alkenes to Alkanes Hydrodehalogenation

300

Alumina

3mm Extrudate

Pd

0.5

Hydrogenation / Dehydrogenation

301

Alumina

3mm Extrudate

Pd

0.5


354

Alumina

4–6mm Spheres

Pd

0.2


355

Alumina

2–4mm Spheres

Pd

0.5


360

Alumina

3mm Tablets

Pd/Ru

0.1/0.1

Alkene to Alkane Hydrogenation

375

Carbon

3mm Extrudate

Pd

1

Reductive Alkylation

382

Carbon

2mm Extrudate

Pd

2


385

Carbon

0.6–0.85mm Granules

Pd

5

Hydrogenation / Disproportionation

386

Carbon

2–5mm Granules

Pd

1


454

Alumina

4mm Ring Extrudate

Pd

1

Hydrogenation of Phenol to Cyclohexanone

73

Alumina

3mm Tablets

Pt

0.3, 0.5

Dehydrogenation Aromatic Ring Hydrogenation Benzene to Cyclohexane Decomposition of Hydrogen Peroxide

176

Alumina

4–8mm Spheres

Pt

1

Amination of Carbonyls Dehydrogenation of Alcohols to Carbonyls

146

Alumina

3mm Tablets

Ru

0.5

Hydrogenation of Aliphatic Carbonyls Aromatic Ring Hydrogenation

642

Carbon

2mm Extrudate

Ru

3

Hydrogenation of Aliphatic Carbonyls Hydrogenation of Olefins Aromatic Ring Hydrogenation

660

Silica

1.5mm Extrudate

Ru

3

Hydrogenation of Carbonyls

520

Alumina

3mm Tablets

Rh

0.5

Hydrogenation of Aromatics


4.12.2 Gas Purification

Such poisons typically include:-

There is a growing requirement for very high purity gases

• carbon monoxide (in industrial H2 derived from syngas)

in a wide variety of applications. In addition to the

• sulfur compounds

purification of chemical feedstreams, there are

• halogen compounds

requirements for ultra–pure gases in the electronic and • oil mists (from compressors)

nuclear industries.

• acid and alkaline sprays (from gas scrubbers) Contaminants such as O2 or H2 frequently need to be removed to single ppm levels in order to prevent such

• heavy metals such as Pb or Hg (in industrial H2 derived by electrolysis)

problems as:• promotion of unwanted side reactions

The use of an elevated temperature may be beneficial if significant quantities of carbon monoxide or sulfur are

• corrosion (or chemical attack) of the reactor itself or of the catalyst

present or if the gas stream is saturated with water vapor. The inlet temperature must always be at least 10°C above

• unwanted modifications to the semiconducting

the dew point of the gas stream to avoid the possibility of liquid water condensing on the active site and reducing

properties of electronic components.

the catalyst’s overall activity. Operation at elevated This has led to the development of a range of PGM

pressures will also improve catalyst efficiency.

catalysts on γ-alumina supports for gas purification. The volumetric gas flow per unit time divided by the overall

Essentially, the reaction is:-

volume of the catalyst bed is known as the Unit Space

2H2

+ O2

2H2O

Velocity. The most common unit of time quoted is the hour. Therefore:

ΔH = - 241.8 kJ/mol

Gas Hourly Space Velocity = Volume of gas flowing/hour (GHSV) Volume of catalyst bed

Thus, for example, O2 may be removed from an inert gas

The GHSV which is required in any specific situation will

(e.g. N2, He etc) by combination with the stoichiometric

depend on:-

amount of hydrogen to form the easily removable water vapor.

• impurity levels present in the inlet gas • maximum allowable impurity level in the outlet gas

These catalysts are simple to use, involving merely the

(i.e. percentage conversion required)

passage of the gas stream through the catalyst bed supported between grids in a suitable reactor vessel.

• concentration of poisons present • gas to be purified.

The catalytic combination of H2 and O2 is an extremely facile reaction. The reaction is exothermic, and the actual

The pressure drop across a catalyst bed is determined by

temperature increase will depend on the concentration of

a number of factors:-

gas component to be removed and the size and thermal insulation of the catalyst bed in use.

• GHSV • aspect ratio of the catalyst bed for a given overall bed

To preserve catalyst activity, the maximum operating

volume i.e. length to diameter ratio

temperature in any such gas phase reaction should be no more than about 600˚C. The water vapor formed can readily be removed downstream from the reactor either cryogenically or using a conventional dryer containing a desiccant such as molecular sieve. Ideally, catalyst poisons

• temperature and pressure • gas viscosity • shape and size of the individual catalyst particulate.

should be eliminated from the process gas stream to maximize catalyst performance and life.


61

It is essential that attrition loss and dust formation be kept

Pressure drop as a function of particulate size and shape is

to a minimum, in order to minimize an increase in

shown below.

pressure drop over time.

3mm Tablets

Pressure Drop

3.5mm Ring Extrudate 5mm Tablets 4-8mm Spheres ∇

7mm Tablets

Superficial Velocity (Hydrogen) Typical Gas Purification Applications

62

Catalyst Type

Nominal Size & Shape of Alumina

PGM

Loading (% Wt)

Applications

48

3 mm Tablets

Pd

0.3, 0.5

O2 from H2, N2, Ar, CO2 by combination with H2

49

3 mm Tablets

Pd

5

H2 removal getter

50

3 mm Tablets

Pd

0.3, 0.5


50A

4–8 mm Spheres

Pd

0.3, 0.5

O2 from H2, N2, Ar, CO2 by combination with H2 O3 from air or water

50B

2–4 mm Spheres

Pd

0.3, 0.5

O2 from H2, N2, Ar, CO2 by combination with H2 O3 from air or water

54

3 mm Tablets

Pd

0.5


73

3 mm Tablets

Pt

0.3, 0.5

H2 from O2, Ar, N2, CO2, air, He, He/Ar by combination with O2. O2 from N2 by reaction with CH4. Hydrocarbons from O2, N2, CO2, air, He, Ar by reaction with O2. CO from CO2, N2, air by combination with O2

146

3 mm Tablets

Ru

0.5

CO or CO2 from H2 by methanation to CH4

256

4-6 mm Spheres

Pt

0.1, 0.3

VOC removal from vent streams by reaction with O2

257

2–4 mm Spheres

Pt

0.1

VOC removal from vent streams by reaction with O2

300

3 mm Tablets

Pd

0.3, 0.5


301

3 mm Tablets

Pd

0.3, 0.5


360

3 mm Tablets

Pd/Ru

0.12/0.12

Reduction of nitrogen oxides to N2 with H2 in the presence of CO and CO2

519

2-4 mm Spheres

Rh

0.5

Decomposition of N2O

520

3 mm Tablets

Rh

0.5

Decomposition of N2O

630

3 mm Tablets

Ru

0.3, 0.5, 1 CO or CO2 from H2 by methanation to CH4


4.13

HOMOGENEOUS CHIRAL CATALYSIS

+

N2CHCO2Me

Cat*

Cilastatin

CO2H 92% ee R R

In 1992 the Food and Drug Administration in the U.S. of single-enantiomers drugs. This has driven the discovery

OC8H7

N Cu O O 2

introduced guidelines to encourage the commercialization Cat* =

R=

of new and efficient methods to access enantiomerically pure compounds. Knowles, Horner and Kagan3 independently reported the Traditionally, enantiomerically pure compounds have been

first examples of homogeneous-catalyzed asymmetric

obtained by classical resolution of racemates or

hydrogenation of olefins employing Rh complexes bearing

transformation of naturally occurring chiral compounds,

chiral phosphines. This novel methodology proved to be

and more recently by chromatographic separation

very successful and Monsanto used it in the preparation

technologies. Biocatalysis is another important tool for the

of the drug L-DOPA, in what became the first industrial

production of single enantiomers, but its applicability is

asymmetric synthesis.

limited by the inherent single-handed, lock-and-key specificity of enzymes. Since the late 1960s, asymmetric H2

organometallic catalysis has become a very powerful AcHN

strategy and is now recognized in industry as a cost-

CO2H

Rh/L*

CO2H

AcHN

H O

72% ee

PPh2 PPh2

effective means of producing chiral intermediates and products.

O

H2 AcHN

Asymmetric catalysis is achieved by the combination of a

Ph

Rh/L*

AcHN

Ph

H DIOP

88% ee

chiral ligand, a metal atom and, in some cases, an achiral additive or other auxiliary ligands. The chosen chiral ligand must have a suitable combination of structure and

These first achievements stimulated further investigations,

functionalities to modify the metal atom, generating

and in 1980 Noyori published his first article on

reactivity and stereoselectivity.

asymmetric hydrogenation of aminoacids employing chiral BINAP, based on the C2 symmetric binaphthyl backbone.

The first examples of enantioselective organometallic catalysis can be traced back to 1966, when Noyori et al.

The high chiral-recognition ability of BINAP-based metal

described the cyclopropanation of alkenes using a salen-

complexes boosted the synthetic applications of

copper complex.1 Although very low enantioselectivities

asymmetric hydrogenation. Soon these complexes were

(~10% ee) were initially reported, fine-tuning of the copper

also used in other catalytic reactions such as the

catalyst allowed Aratani to improve them to 92% ee.2 This

asymmetric isomerization of allylic amines, a reaction

methodology was applied later on to the industrial

employed by Takasago in the industrial synthesis of (-)-

preparation of cilastatin.

menthol from myrcene since 1985. Even more successful has been the use of BINAP-Ru Ph CO2Me

1 mol% Cat*

10% ee

+

+ N2CHCO2Me

CO2Me

complexes in the asymmetric hydrogenation of

Cat* = N O Cu O N Ph

functionalized olefins and ketones. This reaction has been applied to the preparation of several drugs and natural products, including isoquinilone alkaloids.4

6% ee

1 Nozaki, H.; Moruiti, S.; Takaya, H.; Noyori, R. Tetrahedron Lett. 1966, 22, 5239 2 Aratani, T.; Yoneyoshi, Y.; Nagase, T. Tetrahedron Lett. 1975, 31, 1707. 3 Dang, T. P.; Kagan, H. B. J. Chem. Soc. Chem. Commun. 1972, 481. 4 Noyori, R., Nobel Lecture, Angew. Chemie. Int. Ed., 2002, 41, 2008


63

Prof. K. B. Sharpless also shared this 2001 Nobel Prize PO(OCH3)2 PPh2 PPh2

R

(S)-BINAP-Ru dicarboxylate

PO(OCH3)2

NHCHO

R

NHCHO

thanks to his innovative work in the asymmetric epoxidation of olefins. In 1980 Katsuki and Sharpless discovered the titanium-catalyzed asymmetric epoxidation of olefins bearing allylic hydroxy groups.6

BINAP

NEt2

R2

NEt2

[Rh (R)-BINAP]+

OH > 98% ee

OH

R1

t-BuO2H

+

R1

OH

often > 95% ee

Cat* = diethyl tartrate + Ti(Oi-Pr)4

O

R3 O

R2

Cat*

(-)-Menthol

HO

HO

R3

CO2H NCH3 H

OH

H3CO Naproxen

Citronellol

Morphine

The osmium-catalyzed asymmetric dihydroxylation was subsequently discovered in 1987.7 Mechanistic investigations and ligand engineering allowed the

The asymmetric hydrogenation of simple, unfunctionalized ketones remained an unresolved problem until 1995. There Noyori et al. found a general solution based on the use of

application of this second Sharpless reaction to any given class of alkenes, making it a very useful technology in organic synthesis.

a [RuCl2(bisphosphine)(diamine)] complex in the presence

HO

of an alkaline base.5 The newly devised

O

and selective in the hydrogenation of a range of aromatic,

OH

OH

bisphosphine/diamine complex proved to be very active

OH AD-β

AE (+)-DET

heteroaromatic and olefinic ketones in 2-propanol containing t-BuOK or KOH.

OH Geraniol

This method has been applied to the asymmetric

AE (-)-DET

AD-α

synthesis of several drugs, including (R)-denopamine, the HO

O

antidepresant (R)-fluoxetine and the antipsychotic (S)-

OH

OH

duloxetine. OH

AE - asymmetric epoxydation AD - osmium-catalyzed asymmetric dihydroxylation

CF3

H.HCl N

OH

O HO denopamine hydrochloride

During the 1990s, Jacobsen and Katsuki independently

NHCH3.HCl

OCH3 OCH3

developed chiral manganese-salen ligands for the catalytic fluoxetine hydrochloride

precursor of α-damascone

OCH3

OH

OH

O S

NHCH3

OH

epoxidation of alkenes in combination with cheap oxygen sources (i.e. NaClO), enantioselectivities often reaching 98% ee.

precursor of α-tocopherol OCH3

duloxetine

precursor of anthracyclins

During the last decade many new enantioselective reactions have been discovered (aminohydroxylation, aziridination, hydroformylation). Catalysis by palladium

Following the first discoveries in asymmetric

complexes has been actively developed, particularly in the

hydrogenation, the search for new families of chiral

areas of enantioselective allylic substitution and

phosphorous ligands with improved stereo-electronic

asymmetric Heck reaction.

characteristics has become an on-going effort both in academia and industry. Dr. Knowles and Prof. Noyori were awarded the Nobel Prize in Chemistry in 2001 for their outstanding contributions in this subject.

5 6 6 7 7 64

Noyori, R.; Ohkuma, T., Angew. Chemie. Int. Ed., 2001, 40, 1 Katsuki, T.; Sharpless, K. B. J. Am. Chem. Soc. 1980, 102, 5974. Hanson, R. M.; Sharpless, K. B. J. Org. Chem. 1986, 51, 1922. Crispino, G. A.; Sharpless, K. B. Synthesis 1993, 8, 777. Johnson, R. A.; Sharpless, K. B. in Catalytic Asymmetric Synthesis, Ed. Ojima, I., VCH, Weinheim, 1993, p.101 and p. 227.


4.13.1 Asymmetric Hydrogenation

R

CO2R'' NHR'

Rh-catalyzed hydrogenation of dehydroaminoacids

Homogeneous asymmetric hydrogenation is one of the most important chiral technologies Johnson Matthey offers to its customers in the Pharmaceutical and Fine Chemicals industry through its business unit, Catalysis and Chiral

O R

R N Fe PR2 PR2

CO2R'

Technologies (CCT). This portfolio has been developed by combining in-licensed asymmetric ligands from companies and academic institutions with in-house developed catalytic systems. A range of technologies has been assembled that allows, a priori, the coverage of all the known application of asymmetric hydrogenation (C=C, C=O and C=N bonds).

CO2R'

R

CO2R'

Rh-catalyzed hydrogenation of α-ketoesters

Rh-catalyzed hydrogenation of itaconates

Boaz, N. W.; Debenham, S. D.; Mackenzie, E. B.; Large, S. E. Org. Lett. 2002, 4, 2421. Boaz, N. W.; Debenham, S. D.; Large, S. E.; Moore, M. K. Tetrahedron: Asymmetry 2003, 14, 3575.

P-Phos and Xyl-P-Phos

ParaPhos® and PhanePhos

P-Phos, licensed from Prof A. Chan, is a biaryl phosphine

PhanePhos was first reported in 1997, and has since found

with the unique feature of incorporating two methoxy-

applications in rhodium-catalyzed hydrogenation of

substituted pyridine rings in the backbone.8 This

dehydroaminoacids, palladium catalyzed amination,

contributes to the balance of electronic and steric

ruthenium-catalyzed hydrogenation of ß-ketoesters, and

properties that make the P-Phos ligand very active and

ruthenium-catalyzed hydrogenation of non-functionalized

selective in a series of reactions such as ruthenium-

ketones. Johnson Matthey obtained a licence to

catalyzed hydrogenation of ß-ketoesters and

PhanePhos in 2002.

dehydroaminoacids, and ruthenium-catalyzed Investigations into the reactivity of the common precursor

hydrogenation of non-functionalized ketones.

4,12-dibromo[2.2]paracyclophane towards electrophilic aromatic substitution has recently led to the introduction

O R

CO2Me

of the new paracyclophane-based ligands, ParaPhos. This research has improved the efficiency of the ligand

Ru-catalyzed hydrogenation of β-ketoesters

synthesis and has expanded the range of available phosphines by introducing substituents with different

OMe O

Ru-catalyzed hydrogenation of unsaturated acids CO2H R

R'

N MeO MeO N OMe

electronic effects on the paracyclophane backbone while breaking with the requirement for C2 symmetry.

PAr 2 PAr 2 Ru-catalyzed hydrogenation of aromatic ketones

Ar = Ph, Xyl

Both rhodium and ruthenium catalysts bearing the PhanePhos and ParaPhos ligands show an exceptionally high activity in most homogeneous hydrogenation reactions and a surprising high “tunability” associated with the use of different derivatives.9

™ Bophoz™ Bophoz™ is a phosphine-aminophosphine ligand based on the ferrocene backbone. It presents exceptional reactivity

R1 R3HN

O

R2

R

CO2Me

Ru-catalyzed hydrogenation of β-ketoesters

in rhodium-catalysed hydrogenations. The Bophoz™ range of ligands display a rather unique combination of activity and selectivity in the hydrogenation of C=C and C=O bonds (such as in ␣-ketoesters). A commercial agreement with the Eastman Chemical Company for the use of Bophoz™ has been in place since November 2003.

CO2Me

Rh-catalyzed hydrogenation dehydroaminoacids

R

PAr 2 O PAr 2

Boc N N Ac

CO2Me

Ru-catalyzed hydrogenation of aromatic ketones

PhanePhos

R=H

ParaPhosTM

R = CH2OH, CH2OTrityl CH2OTIPS, OMe

8 Pai, C. -C.; Lin, C. -W.; Lin, C. -C.; Chen, C. -C.; Chan, A. S. C.; Wong, W. T. J. Am. Chem. Soc. 2000, 122, 11513. 9 Rossen, K.; Pye, P. J.; Reamer, R. A.; Tsou, N. N.; Volante, R. P.; Reider, P. J. J. Am. Chem. Soc. 1997, 119, 6207. 9 Domínguez, B.; Hems, W. P.; Zanotti-Gerosa, A. Org. Lett. 2004, 6,1927.


65

BINAM-P and Spiro-P

suited to provide the best ligands for this catalysis when

These structurally diverse ligands have been developed by Professor Chan of Hong Kong Polytechnic University. Johnson Matthey obtained a licence in 2002. BINAM-P is

used in combination with diamine ligands such as DPEN, DACH and DAIPEN.

Transfer hydrogenation technology

an amino-phosphine ligand with axial chirality characterized by a larger than usual dihedral angle that is a consequence

Ruthenium transfer hydrogenation catalysts bearing

of the partially reduced binaphthyl backbone. Spiro-P is a

tosylated diamine ligands were developed by Noyori and

phosphinite ligand based on the concept of a spiro-bicyclic

Ikariya, and are included in the license agreement

backbone.10

between JST and Johnson Matthey.

Both ligands have found excellent applications in the

The reduction of C=O groups in presence of i-PrOH and a

rhodium-catalyzed hydrogenation of dehydroaminoacids.

base or in the presence of a mixture of formic acid and triethylamine must be considered complementary to hydrogenation technology.12 Transfer hydrogenation gives

Ar2P PAr 2 O O

NHPAr 2 NHPAr 2

excellent selectivity on “difficult” substrates such as cyclic ketones, acetylenic ketones and imines.

i-PrOH / t-BuOK or

O

Spiro-P

BINAM-P

R

OH R

HCO2H/Et3N, 5/2

Ts Ph

N

Ph

Ru N Cl H2

Typical products obtained

Asymmetric Ketone Reduction In i-PrOH / t-BuOK

Ketone hydrogenation technology

OH

Dynamic kinetic resolution in i-PrOH / t-BuOK OH

In HCO2H/Et3N OH

OH

OH

The discovery by Professor Noyori’s group that nonfunctionalized aromatic ketones can be efficiently reduced

NHCbz

by ruthenium catalysts was a dramatic leap forward in the

H3CO

OH

OH

field of asymmetric homogeneous hydrogenation. The

NH

H3CO

broad applicability of the technology and the exceptionally

R

high activity of these catalysts makes asymmetric ketone hydrogenation the route of choice to chiral alcohols.11

4.13.2 Enantioselective Hydroamination

The Japan Science and Technology Corporation (JST) licensed this technology to Johnson Matthey in 2003. Two families of ligands, P-Phos and ParaPhos, are perfectly

This technology has been exclusively in-licensed from Yale (Professor John Hartwig). Johnson Matthey is optimizing

Ar P

Ar Cl Ru

P O

Ar

Ar Cl

the system for each particular substrate.

NH2 NH2 OH

t-BuOK, H2

H2N

NH2

NHAr

R

R

Potential Intermediate

ee > 98%

[(R)-P-Phos)Pd(OTf) 2]

Typical products obtained

Diamines

arylamine, toluene, 25o C

OH

OH NH2

Pd H L L

Fe

F3C NH2

DPEN H2N

NH2

DACH

Me NHAr

OH O

OMe

F3C high yield and high ee

MeO OH

OMe Me2N OMe

10 10 11 11 12 66

DAIPEN

OH OH

Zhang, F.-Y.; Pai, C. -C.; Chan, A. S. C. J. Am. Chem. Soc. 1998, 120, 5808. Chan, A. S. C.; Hu, W.; Pai, C. -C.; Lau, C. -P.; Jiang, Y.; Mi, A.; Yan, M.; Sun, J.; Lou, R.; Deng, J. J. Am. Chem. Soc. 1997, 119, 9570. Noyori, R.; Ohkuma, T. Angew. Chem. Int. Ed. 2001, 40, 1. Noyori, R. Nobel Lecture, Angew. Chem. Int. Ed. 2002, 41, 2008. Haack, K. J.; Hashiguchi, S.; Fujii, A.; Ikariya, T.; Noyori, R. Angew. Chem. Int. Ed. 1997, 36, 285 and 288.


4.13.3 Enantioselective Alkyne Addition

4.13.5 CATAXA™ Anchored Catalysts

Developed by Professor Erick Carreira of ETH (Zurich).

Rhodium CATAXATM catalysts

O H

H

HO

R2

The hydrogenation of prochiral carbon-carbon double

R1

bonds using enantioselective organometallic complexes of

H

R1

R2

(+)-N-methyl ephedrine Zn(OTf) 2, Et3N

R1 = H or alkyl/aryl

rhodium is widely used in chiral organic synthesis. However, extensive purification of the products is often necessary to remove the rhodium, and/or expensive

R1 can be aryl or alkyl - linear or branched sterically

phosphine ligands from the product.

crowded. Enantiomeric excesses are generally above 98%. This methodology can be applied to the synthesis of

Johnson Matthey has anchored a range of rhodium

1,4-diols

catalysts on alumina, CATAXATM/ Rh, which are easily collected by filtration after the reaction and show Ph O (+)-N-Methylephedrine

negligible amounts of leaching into the reaction mixtures.

O

Me

Me Me

Ph O

OH 99% ee 93:7 diastereoselectivity

O

O

Me

Me

H Ph

Me

Me

By attaching chiral homogeneous catalysts onto an alumina

Me

O Me (-)-N-Methylephedrine

via a heteropolyacid, the high enantioselectivity and mild reaction conditions of the analogous homogeneous system can be combined with the ease of separation and simple method of recycle which is observed with

O

heterogeneous catalysts. In addition, the support can add Me

Me

Me OH

99% ee 92:8 diastereoselectivity

an extra dimension by exerting a positive influence on the enantioselectivity of the catalyst. In many instances, CATAXATM catalysts can be reused. The ability of the catalyst to recycle will depend on a number of factors including:

4.13.4 Asymmetric Michael Addition The La-BINOL complex for asymmetric Michael reaction is a highly stable powder. It has application for a broad range of substrates: cyclic enones (5-9 membered ring), acyclic enones and ß-dicarbonyl compounds.13 The homogeneous asymmetric complex can easily be recovered (ee > 98%) even after 4 recycles).

• The conditions under which they are used (whether the catalyst is exposed to air, moisture etc before/during/after the reaction); • The solvent in which the catalyst is used (some solvents, particularly alcohols, can themselves help to stabilize low co-ordinate metal complexes).

O O

R=

CO2Et O CO2Et

O O La O HO

R

All the ligands and catalysts discussed in this review are available through Alfa Aesar, a Johnson Matthey Company.

13 Matsunaga, S.; Das, J.; Roels, J.; Vogl, E. M.; Yamamoto, N.; Lida, T.; Yamaguchi, K.; Shibasaki, M. J. Am. Chem. Soc. 2000, 122, 2252. Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc 1999, 121, 4168. Shibasaki, M.; Sasai, H.; Arai, T. Angew. Chemie Int. Ed. Engl. 1997, 36, 1236.


67

A variety of CATAXATM supported rhodium catalysts are

A precursor version of CATAXATM/ Rh catalysts is also

available. These are based on the general structure shown

available, CATAXATM/ Rh(COD)2. This material will allow the

below. The complexes can be chiral or achiral. Each catalyst

in-situ preparation of supported Rh catalysts by a simple

will exhibit different rates dependent on the solvents and

ligand exchange reaction with the desired diphosphine

substrate used.

ligand. The resultant catalysts generally require a prehydrogenation step for the pre-formed CATAXATM/ Rh/

Examples of diphosphine ligands:

Phosphine catalysts.

-dppb (1,4-bis(diphenylphosphine)butane). -(S,S)-BDPP (SkewPhos). -(S,S)-DIPAMP. Examples of dienes: -Cyclooctadiene. -Norbornadiene.

CATAXA™/ Rh(COD)2

Choice of solvent CATAXATM/ Rh/ Phosphine catalysts Many different solvents can be used in conjunction with The CATAXATM/ Rh catalysts exhibit similar or often higher enantioselectivity or selectivity to their homogeneous counterparts in reactions such as hydrogenation of dimethylitaconate (DMIT), to acetamido cinnamate (below) and geraniol.

CATAXA™/ Rh catalysts. The choice of solvent will depend largely on the substrate and the type of supported catalyst being used. Solvents such as ethanol and toluene have been used successfully with this material. As the material is air and moisture sensitive, we also recommend the use of dried and degassed solvents. Note: - Like many organometallic complexes, CATAXATM/ Rh samples are prone to oxidation and hence deactivation. To increase the shelf life of these materials they must be stored and handled under an inert atmosphere.

H H +

S

68

R


5.

Table: Heterogeneous Catalysts

Catalyst Type

Support Material

Metal Loading %

Typical Applications

A101023-10

Carbon Powder

10

Dehydrogenation

A101023-5

Carbon Powder

5

Hydrogenation of aliphatic nitro compounds

A101038-10

Carbon Powder

10

Dehydrogenation

A102023-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, nitriles, aromatic carbonyls, reductive alkylation, reductive amination, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation, C-C coupling

A102038-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic rings, aromatic carbonyls, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation

A103038-5

Carbon Powder

5

Selective hydrogenation where lower activity is required

A105023-5

Carbon Powder

5

Conversion of phenol to cyclohexanone

A109047-5

Carbon Powder

5

Hydrogenation of aromatic nitriles, imines, oximes, reductive amination, reductive alkylation, C-C coupling

A201053-10

Barium Sulfate

10


A201053-5

Barium Sulfate

5


A302023-5

Carbon Powder

5

Rosenmund Reduction

A302038-5

Carbon Powder

5

Rosenmund Reduction

A303060-5

Calcium Carbonate

5


A305060-5

Calcium Carbonate

5

Selective hydrogenation of alkynes to alkenes

A306060-5

Calcium Carbonate

5

Selective hydrogenation of alkynes to alkenes

A308053-5

Barium Sulfate

5


A401002-20

Carbon Powder

20

Hydrogenolysis, debenzylation

A401102-5

Carbon Powder

5

Hydrogenation of aromatic and aliphatic nitro compounds

A402002-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, hydrogenolysis, hydrodehalogenation, debenzylation

A402028-10

Carbon Powder

10


A402028-5

Carbon Powder

5


A402032-10

Carbon Powder

10


A405028-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic and aliphatic nitro compounds, hydrogenolysis, hydrodehalogenation, debenzylation, C-C coupling

A405032-5

Carbon Powder

5


A470085-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic rings, aromatic and aliphatic nitro compounds, aromatic carbonyls, hydrogenolysis, debenzylation, C-C coupling

A470129-10

Carbon Powder

10


A470129-20

Carbon Powder

20


A470129-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic and aliphatic nitro compounds, aromatic carbonyls, hydrogenolysis, debenzylation

A470201-5

Carbon Powder

5

Hydrogenation of aromatic and aliphatic nitro compounds, aromatic carbonyls

A501023-10

Carbon Powder

10

Hydrogenolysis, debenzylation, dehydrogenation

PALLADIUM


69

Catalyst Type

Support Material

Metal Loading %


A501032-10

Carbon Powder

10


A501038-10

Carbon Powder

10

Dehydrogenation

A503023-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, nitriles, aromatic carbonyls, reductive alkylation, reductive amination, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation, C-C coupling, isomerization

A503032-5

Carbon Powder

5

Hydrogenation of nitro and nitroso compounds, imines, nitriles, oximes, reductive alkylation, reductive amination, hydrogenolysis, debenzylation

A503038-5

Carbon Powder

5

Hydrogenation of aromatic carbonyls, hydrogenolysis, hydrodehalogenation, isomerization

A505085-5

Carbon Powder

5

Hydrogenation of aromatic and aliphatic nitroso compounds

A570147-5

Carbon Powder

5

Hydrogenation of nitro and nitroso compounds, imines, nitriles, oximes, reductive alkylation, reductive amination, isomerization

A570129-5

Carbon Powder

5

Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, oximes, aromatic carbonyls, nitriles, reductive alkylation, reductive amination, hydrogenolysis, hydrodehalogenation, selective oxidation, dehydrogenation, isomerization

A570201-5

Carbon Powder

5

Hydrogenation of aromatic carbonyls, nitriles, hydrogenolysis, hydrodehalogenation

A701023-5

Carbon Powder

5

Rosenmund Reduction

B101002-5

Carbon Powder

5

Selective oxidation

B101032-3

Carbon Powder

3

Hydrogenation of halonitroaromatics

B101038-1

Carbon Powder

1


B102022-5

Carbon Powder

5

Hydrogenation of heterocyclic compounds

B102032-1

Carbon Powder

1

Hydrogenation of halonitroaromatics, p-aminophenol production

B102032-3

Carbon Powder

3

Reductive alkylation

B103018-5

Carbon Powder

5

Hydrogenation of aliphatic carbonyls, dehydrogenation, selective oxidation

B103032-3

Carbon Powder

3


B103032-5

Carbon Powder

5

Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls, dehydrogenation, selective oxidation

B104032-3

Carbon Powder

3


B105032-3

Carbon Powder

3


B105047-1

Carbon Powder

1

Hydrogenation of halonitroaromatics, p-aminophenol production

B106032-3

Carbon Powder

3


B111022-5

Carbon Powder

5

Selective oxidation

B112002-5

Carbon Powder

5

Selective oxidation

B170058-1

Carbon Powder

1

p-Aminophenol production

B170147-1

Carbon Powder

1


B170147-3

Carbon Powder

3

Hydrogenation of halonitroaromatics, reductive alkylation

PLATINUM

70


Catalyst Type

Support Material

Metal Loading %


PLATINUM – continued B170147-5

Carbon Powder

5

Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls

B170201-5

Carbon Powder

5

Selective oxidation

B171147-3

Carbon Powder

3


B301013-5

Alumina Powder

5

Hydrosilylation

B301099-5

Alumina Powder

5

Hydrosilylation

B501032-5

Carbon Powder

5

Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls, dehydrogenation, selective oxidation

B503032-5

Carbon Powder

5

Selective oxidationIRIDIUM

C101023-5

Carbon Powder

5

Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitro compounds, aliphatic nitriles, alkenes

C101038-5

Carbon Powder

5

Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitro compounds, aliphatic nitriles, alkenes

C301011-5

Alumina Powder

5

Hydrogenation of aromatic rings

D101023-5

Carbon Powder

5

Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls, sugar hydrogenation, selective oxidation

D101038-5

Carbon Powder

5


D103002-5

Carbon Powder

5

Selective oxidation

D170201-5

Carbon Powder

5


E101049-4/1

Carbon Powder

4% Pd 1% Pt

Hydrogenation of alkenes, nitro and nitroso compounds, imines, selective oxidation

E101023-4/1

Carbon Powder

4% Pd 1% Pt

Hydrogenation of alkenes, nitro and nitroso compounds, imines, selective oxidation

F101023-4.5/0.5

Carbon Powder

4.5% Pd 0.5% Rh Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitriles, oximes

F101038-4.5/0.5

Carbon Powder

4.5% Pd 0.5% Rh Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitriles, oximes

G101038-5/0.25

Carbon Powder

5% Ru 0.25% Pd Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls

RHODIUM

RUTHENIUM

MIXED METAL

NOTE Paste catalysts are free flowing, powder–like materials, usually containing approximately 50–60% w/w water.


NOTE The foregoing lists of catalysts and applications are not exhaustive

71

PRICAT® Catalysts PRICAT

Metal

Support

Promotors

Powder

Tablet

%

Ni 52/35

x

x

50

Kieselguhr

x

Ni 55/5

x

x

55

Kieselguhr

x

Ni 56/5

x

55

Kieselguhr

x

Ni 62/15

x

60

Kieselguhr

x

x

Ni 60/15

x

x

60

Kieselguhr

x

x

Cu 51/8

MgO

x

51

Silica

Cu 60/35

x

x

62

Silica

x

Co 40/55

x

x

40

Kieselguhr

x

ZrO2

Cr2O3

Al2O3

MnO

x

x x

SPONGE METAL

72

Product

Primary Metal

Promoters

Particle Size, median (u)

Typical applications

A-5000 A-5B00 A-5200

Nickel Nickel Nickel

Non-promoted Non-promoted Non-promoted

35 50 175

General hydrogenation General hydrogenation General hydrogenation

A-4000

Nickel

Fe & Cr

35

Diamine hydrogenation

A-7000 A-7200

Nickel Nickel

Mo Mo

35 175

Polyol hydrogenation General hydrogenation

A-7063 A-7B63

Nickel Nickel

Mo Mo

35 50

Polyol hydrogenation Polyol hydrogenation

A-7B73

Nickel

Mo

50

Polyol hydrogenation

A-2000

Nickel

Fe

35

Nitro group hydrogenation

A-3B00

Copper

Non-promoted

50

Dehydrogenation

A-8000 A-8B46

Cobalt Cobalt

Non-promoted Cr & Ni

35 50

Selective hydrogenation Selective hydrogenation

AMCAT-5 AMCAT-5343 AMCAT-7 AMCAT-2

Nickel Nickel Nickel Nickel

Non-promoted Non-promoted Mo Fe

35 35 35 35

In In In In

primary fatty amine tertiary fatty amine primary fatty amine primary fatty amine


6. Table: Homogeneous Catalysts Our range of PGM homogeneous catalysts and precursors is listed in the tables below. We have also listed some simple PGM chloride salts which are the starting materials for most co–ordination compounds.

An explanation of the European Union (E.U.) hazard codes is given below:

E.U. Code

Hazard

Nature of the Hazard

Xi

Irritant

–

Non-corrosive substances which, through immediate, prolonged or repeated contact with the skin or mucous membrane may cause inflammation.

C

Corrosive

–

Substances which may, on contact with living tissues, destroy them.

O

Oxidizing

–

Substances which give rise to a highly exothermic reaction in contact with other substances, particularly flammable substances.

F

Highly flammable

–

Solid substances which may readily catch fire after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source of ignition.

Xn

Harmful

–

Substances which may cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.

T

Toxic

–

Substances which in low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.

T+

Very toxic

–

Substances which in very low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.

CSNYFT

Caution Substance not yet fully tested.

–

New substance – not the subject of a full notification.

N

Dangerous for the Environment

–

Chemicals that may present an immediate or delayed danger to one or more components of the environment.

Solubilities The relative solubilities of the co–ordination compounds in different solvents are indicated in the tables. For guidance, the following abbreviations have been used:– v.s.

very soluble

ca. 1000 g/l

s.

soluble

ca. 100 g/l

f.s.

fairly soluble

ca. 15 g/l

sl.s.

slightly soluble

ca. 10 g/l

v.sl.s.

very slightly soluble

ca. 1 g/l or less

i

insoluble


73

IRIDIUM COMPOUNDS Catalog No.

Compound

Color & Form

Mol Wt

% Metal Content

Stability

Ir-40

Carbonylchloro bis (triphenylphosphine) iridium(l) [IrCl(CO) (PPh3)2]

lemon yellow crystals

780

24.6

air stable

Ir-42

Carbonylhydrido tris (triphenylphosphine) iridium(l) [IrCl(CO)H(PPh3)3]

pale yellow powder

1007

19.1

slowly decomposes in air

Ir–90

(Cycloocta–1,5–diene) pyridyl tricyclohexyl– phosphine iridium(I) hexafluorophosphate [Ir(COD)py(PCy3)]PF6

orange crystals

804

23.9

air stable

Ir–91

Di -mu-chloro bis(cyclooctene) iridium (I) [Ir(C8H14)2Cl]2

yellow solid

896

42.9

slowly decomposes in air & moisture

Ir–92

Bis(1,5-cyclooctadiene)di- mumethoxydiiridium(I) [Ir(C8H12)2OCH3]2

yellow solid

651

58.0

slowly decomposes in air & moisture

Ir–93

Di μ–chloro bis (η4–cycloocta–1,5– diene) di–iridium(I) [IrCl(COD)]2

red– orange solid

671

57.2

air stable

Ir–112

"Iridium(III) acetate" Hexa(acetato) μ3–oxo tris (aquo) tri–iridium acetate [Ir3(OAc)6μ3–O(H2O)3]OAc

dark green solid

50–54

air stable

Iridium(III) chloride hydrate [IrCl3].H2O

green/ black crystalline flakes

50–56

air stable hygroscopic

Chloroiridic acid; Hydrogen hexachloroiridate(IV) hydrate H2[IrCl6].H2O

black– brown crystals

38–45


FibreCat® 4000-D11

Ir(COD)Cl on triphenylphosphine fibers

orange fiber

4.0-5.0

air stable

FibreCat® 4000-D12

Ir(COD)Cl on pyridine fibers

yellow fiber

4.0-5.0

air stable

OSMIUM COMPOUNDS Catalog No. Compound

74

Color & Form

Mol Wt

% Metal Content

Stability

Osmium tetroxide Osmium (VIII) oxide [OsO4]

yellow crystals

254

75

m.pt 41°C

“Potassium osmate dihydrate” Dipotassium trans dioxo tetra (hydroxy) osmium (VI) K2[OsO2(OH)4]

purple solid

368

51.6

air stable

FibreCat® 3003

OsO4 on pyridine fibers

yellow fiber

7.5 nominal

store cold -20°C

FibreCat® 3004

K2[OsO2(OH)4] on triethylamine fibers

violet fiber

7.5 nominal

store cold -20°C


IRIDIUM COMPOUNDS Solubilities

E.U. Hazard Code CAS No. (EINECS No.)

Use and Comments

Catalogue No.

sl.s Chloroform sl.s toluene

T

14871–4–1 (2389416)

Hydrogenation Vaska’s compound

Ir–40

s. chloroform s. toluene

Xn

17250–25–8

Hydrogenation

Ir–42

sl.s acetone, dichloromethane, diethyl ether, ethanol

Xn CSNYFT

64536–78–3 ( –– )

Hydrogenation Crabtree's catalyst

Ir–90

i.water

12246-51-4

Imine Hydrogenation Chiral Hydrogenation

Ir–91

i. water

12148-71-9

Imine Hydrogenation Chiral Hydrogenation

Ir–92

Ir–93

s. chloroform, toluene sl.s acetone, alcohol

Xi

12112–67–3 (2351707)

Hydrogenation

s. acetic acid, water

Xi CSNYFT

52705–52–9 ( –– )

Catalyst precursor Ir–112 Solid contains metal in more than one formal oxidation state Also available in solution in acetic acid

s. alcohol, water

Xn

14996–61–3 * (2330446)

Catalyst precursor

f.s alcohol, water

C

16941–92–7 (2410128)

Catalyst precursor Also available as solution

i. all known solvents

hydrosilylation and hydrogenation

FibreCat® 4000–D11


hydrosilylation and hydrogenation

FibreCat® 4000–D12

*CAS No. refers to a specific hydrate

OSMIUM COMPOUNDS Solubilities

E.U. Hazard Code

CAS No. (EINECS No.)

Use and Comments

v.s carbon tetrachloride s. water

T+, C

20816–12–0 (2440587)

Oxidation Can be readily sublimed. Should only be used in a well ventilated remote environment.

s. water

Xi

19718 – 36 – 6 (2432471)

Oxidation. A convenient substitute for OsO4


T+

Oxidation

FibreCat® 3003


Xi

Oxidation

FibreCat® 3004


Catalog No.

75

PALLADIUM COMPOUNDS

76

Catalog No.

Compound

Color & Form

Mol Wt

% Metal Content

Stability

Pd–62

Dichloro bis(acetonitrile)palladium(II) [PdCl2(CH3CN)2]

dark yellow powder

263

40.4

air stable

Pd–63

Tetrakis(acetonitrile)palladium(II) tetrafluoroborate Pd(CH3CN)4(BF4)2

pale yellow powder

444

23.9

air, moisture & light sensitive

Pd–70

Bis(acetylacetonato)palladium(II) [Pd(acac)2]

yellow orange solid

304

35.0

air stable

Pd–93

Bis(dibenzylideneacetone)palladium(0) Pd(C17H14O)2

purple brown

575

18.5

slightly air & moisture sensitive

Pd–94

Tris(dibenzylideneacetone)dipalladium(0) Pd2(C17H14O)3

dark purple solid

916

23.2


Pd–95

Tris(dibenzylideneacetone)dipalladium(0) chloroform adduct Pd2(C17H14O)3.CHCI3

purple powder 1035

20.6


Pd–100

Dichloro bis(triphenylphosphine) palladium(II); [PdCl2(PPh3)2]

yellow solid

701

15.2

air stable

Pd–101

Tetrakis(triphenylphosphine)palladium(0) [Pd(PPh3)4]

yellow solid

1154

9.4

air, heat, light & moisture sensitive

Pd–102

Diacetato 1,3–bis(diphenylphosphino) propane palladium(II) [Pd(OAc)2(Ph2PCH2CH2CH2PPh2)]

cream solid

636

16.7

air stable moisture sensitive

Pd–103

Dichloro 1,2–bis(diphenylphosphino) ethane palladium(II) [PdCl2(Ph2PCH2CH2PPh2)]

off white powder

575

18.5

air stable

Pd–105

Dichloro 1,4–bis(diphenylphosphino) butane palladium(II) [PdCl2(Ph2PCH2CH2CH2PPh2)]

yellow solid

603

17.6

air stable

Pd–106

Dichloro 1,1-bis(diphenylphosphino)ferrocene orange/red palladium(II) dichloromethane adduct solid [Pd(dppf)Cl2]. CH2CI2

816

13.0

air stable

Pd–107

Dichloro 1,1-bis(diphenylphosphino) ferrocene palladium(II) acetone adduct [Pd(dppf)Cl2]. (CH3)2O

brick red solid

789

13.4

air stable

Pd–109

Di–μ–chloro–bis (tris(2,4–di–t–butylphenyl) phosphite–2–C,P) dipalladium(II)

white – off white powder

1576

13.5

air stable

Pd–110

Di-μ-chlorobis(eta 3-2 propenyl) dipalladium [Pd(C3H5)Cl]2 Allylpalladium chloride dimer

yellow powder

366

58.1

very slightly air & moisture sensitive


PALLADIUM COMPOUNDS

Solubilities

E.U. Hazard Code


Use and Comments

s. acetone, chloroform

Xn

14592–56–4 (2386373)

Coupling precursor, rearrangements, Pd–62 debromination.

21797-13-7

Coupling

Pd–63

14024–61–4 (2378598)

Alkene dimerisation, cyclization, oxidation

Pd–70

sls. chloroform

32005-36-0

Coupling reactions

Pd-93

s. chloroform

51364-51-3 52409-22-0 60748-47-2

Coupling reactions

Pd-94

52522-40-4

Coupling reactions

Pd-95

s. water

s. chloroform, toluene

Xi

Catalog No.

v.sl.s acetone, chloroform

Xn

13965–03–2 (2377442)

Carbonylation. Coupling reactions

Pd–100


Xn

14221–01–3 (2380869)

Coupling reactions. Store refrigerated

Pd–101

s. acetic acid, chloroform, methanol sl.s acetone v.sl.s toluene

Xn CSNYFT

149796–59–8 (–)

Coupling reactions. Carbonylation

Pd–102

Xn CSNYFT

19978–61–1 (–)

Coupling reactions

Pd–103

Xn CSNYFT

29964–62–3 (–)

Coupling reactions

Pd–105

95464-05-4

Coupling reactions

Pd-106

sl.s DMF v.sl.s. acetonitrile, water

i. water

s. chloroform sl. s. dichloromethane

Xn CSNYFT

851232-71-8 (–)

Coupling reactions Carbonylation

Pd–107

i. water s. toluene, chloroform

Xn CSNYFT

217189–40–7 (–)

Coupling reactions especially Suzuki and Stille couplings of aryl bromides and iodides

Pd–109

12012-95-2

Coupling reactions

Pd-110

i. water


77

PALLADIUM COMPOUNDS

78

– (CONTINUED)

Catalog No.

Compound

Color & Form

Pd–111

Palladium(II) acetate trimer Hexakis(μ–acetato) tripalladium(II) [Pd(OAc)2]3

Pd-113

Mol Wt

% Metal Content

Stability

orange/brown 673 needles

47.4

air stable

Dibromo bis(tri-tert-butylphosphine) dipalladium (I) [Pd(μ-Br)t-Bu3P]2

dark green/ black crystals

777

27.4

air & moisture sensitive

Pd-114

Dichloro bis(tricyclohexylphosphine) palladium(II) PdCl2[(C6H11)3P]2

yellow powder

738

14.4

air stable

Pd-115

Dichloro bis(tri-ortho-tolylphosphine) palladium(II) PdCl2[P(o-tolyl)3]2

yellow/orange 786 solid

13.5

air stable

Pd-116

Bis(tri-tert-butylphosphine)palladium(0) Pd(t-Bu3P)2

off white solid

510

20.9

air & moisture sensitive

Pd-117

Dichloro bis(diphenylphosphinophenyl)ether palladium(II) DPEPhos PdCl2

light yellow solid

719

14.8

air stable

Pd-118

Dichloro 1,1-bis(di-tert-butylphosphino) ferrocene palladium(II) di-t-bpfPdCl2

dark red/brown 651 solid

16.3

air stable

Pd-119

Dichloro 1,1-bis(di-isopropylphosphino) ferrocene palladium di-isoppf PdCl2

orange red solid

595

17.8

air stable

Pd–120

Dibromo 1,1-bis(tri-ortho tolylphosphine)palladium(II) PdBr2[P(o-toly)3]2

orange/yellow 875 solid

12.0

Slowly decomposes in air & moisture

Pd–121

Dibromo 1,1-bis(diphenylphosphino) ferrocene palladium(II) dppfPdBr2

purple red solid

820

12.9

air stable

Pd-130

Dibromo bis(triphenylphosphine) palladium (II) [Pd(PPh3)2Br2]

orange solid

791

13.5

air stable

FibreCat® 1001

Pd(OAc)2 on triphenylphosphine fibers

yellow/brown fiber

2.7-4.0

air stable

FibreCat® 1026

PdCI2 on triphenylphosphine fibers

orange fiber

3.5-5.5

air stable

FibreCat® 1032

Pd(OAc)2/tri-tert-butylphosphine on tritertbutylphosphine fibers

yellow fiber

4.5-5.5

air stable

Q Phos

1,2,3,4,5-Pentaphenyl-1’-(di-tert butylphosphino)ferrocene CTC-Q-PHOS (Use in conjunction with Pd precursor)

pink-red solid

711

n/a

air & moisture stable

Palladium(II) chloride [PdCl2]

red– brown powder

177

59.6–60.0

air stable


PALLADIUM COMPOUNDS

– (CONTINUED)

Solubilities

E.U. Hazard Code


Use and Comments

Catalog No.

s. acetic acid, toluene

Xi

3375–31–3 (2584249)

Carbonylation. Coupling precursor. Slowly decomposes in alcohol solutions

Pd–111

i. water

185812-86-6

Highly active for all coupling reactions especially amination and Suzuki couplings

Pd-113

i. water

29934-17-6

Coupling reactions

Pd-114

i. water

40691-33-6

Coupling reactions

Pd-115

i. water (but decomposes)

53199-31-8

Highly active for all coupling reactions especially amination and Heck couplings

Pd-116

i. water

205319-06-08

Coupling reactions

Pd-117

i. water

95408-45-0

Highly active for all coupling reactions especially Suzuki couplings

Pd-118

i. water

215788-65-1

Coupling reactions

Pd-119

i.water

24554-43-6

Coupling

Pd–120

s. chloroform, dichloromethane

124268-93-5

Coupling

Pd–121

v.sl. s. acetone, acetonitrile

25044-96-6 (-)

Coupling reactions

Pd-130


Bromo/iodo coupling reactions

FibreCat® 1001


Bromo/iodo coupling reactions

FibreCat® 1026


Highly active for all coupling reactions especially chloro coupling, amination

FibreCat® 1032

i. water

s. dil mineral acids and aqueous alkali metal halides


Xi

312959-24-3

Highly active for all coupling reactions especially Negishi couplings

7647–10–1 (2315962)

Catalyst precursor. Also available as H2PdCl4 solution

79

PLATINUM COMPOUNDS Catalog No.

Compound

Color & form

Mol Wt

% Metal Content

Stability

Pt–62

trans–Bis(acetonitrile) dichloroplatinum(II) trans–[PtCl2(CH3CN)2]

pale yellow micro– crystals

348

56.0

air stable

Pt–70

Bis(acetylacetonato) platinum(II); [Pt(C5H7O2)2]

lemon needles

393

49.6

air stable

Pt–90

Dichloro (η4–norbornadiene) platinum(II) [PtCl2(nbd)]

cream micro– crystals

358

54.4

air stable

Pt–91

(η4–Cycloocta–1,5–diene) diiodoplatinum(II) [PtI2(COD)]

yellow powder

557

35.0

air stable

Pt–96

Dichloro (η4 cycloocta–1,5–diene) platinum(II) [PtCl2(COD)]

pale yellow solid

374

52.1

air stable

Pt–100

cis–Dichlorobis (triphenylphosphine) platinum(II) cis–[PtCl2(PPh3)2]

white crystals

790

24.7

air stable

Pt–112

trans–Dichlorobis(diethylsulfide) platinum(II) trans–[PtCl2(SEt2)2]

bright yellow crystals

446

43.7

air stable

Pt–114

Karstedt catalyst solution Approximate formula Pt2(divinyltetramethyldisiloxane)3

pale yellow solution

3–4

air stable, store less than 50°C

FibreCat® 4001

Chloroplatinic acid on pyridine fibers

orange fiber

3.5-6.0

air stable

Platinum(II) chloride [PtCl2]

olive green powder

72.8 –73.6

air stable

Chloroplatinic acid; Hydrogen hexachloroplatinate(IV) hydrate H2[PtCl6].H2O

orange –red crystals

39 –42


266

RHODIUM COMPOUNDS

80

Catalog No.

Compound

Color & Form

Mol Wt

% Metal Content

Stability

Rh–40

Carbonylchloro bis (triphenylphosphine) rhodium(I) [RhCl(CO)(PPh3)2]

yellow crystals

691

14.9

air stable

Rh–42

Carbonyl hydrido tris (triphenylphosphine) rhodium(I) [RhH(CO)(PPh3)3]

yellow crystals

918

11.2

air stable

Rh–43

Acetylacetonatocarbonyltriphenylphosphine rhodium(I) (ROPAC) [Rh(acac)(CO)(PPh3)]

yellow crystals

492

20.9

air stable

Rh–50

Acetylacetonatodicarbonyl rhodium(I) [Rh(acac)(CO)2]

green flakey crystals

258

39.9

air stable

Rh–70

Tris(acetylacetonato) rhodium(III) [Rh(acac3)]

yellow crystals

400

25.8

air stable


PLATINUM COMPOUNDS Solubilities

E.U. Hazard Code CAS No. (EINECS No.)

v.sl.s acetone i. dichloromethane t.s. DMF

T

13869–38–0 (2376192)

Pt–62

v.s chloroform

Xn

15170–57–7 (2392235)

Pt–70

s. acetic acid

Xn

12152–26–0 (2352716)

Hydrosilylation

Pt–90

s. dichloromethane

Xn

12266–72–7 (2355387)

Hydrosilylation

Pt–91

sl.s. chloroform, dichloromethane v.sl.s. alcohols

Xn

12080–32–9 (2351445)

Hydrosilylation

Pt 96

v.sl.s. chloroform, hexane, toluene

Xn

15604-36-1 (2334959)

v.s acetone s. ethyl acetate

Xn

15337–84–5 (2393731)

Hydrosilylation

Pt–112

68478–92–2 (2708444)

Hydrosilylation. Usually supplied in propan–2–ol/ divinyltetramethyldisiloxane.

Pt 114

Hydrosilylation

FibreCat® 4001

Dictated by solvent used

Use and Comments

Catalog No.

Pt–100


C, T

v.sl.s acetone, alcohol, water

Xn

10025–65–7 (2330341)

Hydrosilylation

v.s acetone, alcohol, ether, ethyl acetate, water

C, T

16941–12–1 (2410107)

Hydrosilylation. A powerful sensitiser and allergen

RHODIUM COMPOUNDS Solubilities

E.U. Hazard Code


Use and Comments

Catalog No.

f.s chloroform, ethanol

T

13938–94–8 (2377128)

Decarbonylation

Rh–40

17185–29–4 (2412303)

Hydroformylation

Rh–42

f.s chloroform

s. chloroform f.s toluene

Xi

25470–96–6 (2470150)

Hydroformylation. ROPAC

Rh–43

s. acetone sl.s alcohol, chloroform, toluene

T, F

14874–82–9 (2389479)

Hydroformylation. Dichromic green–red crystals when crushed

Rh–50

v.s chloroform s. alcohol © 2008 Johnson Matthey Plc

14284–92–5 (2381925)

Rh–70 81

RHODIUM COMPOUNDS

82

– (CONTINUED)

Catalog No.

Compound

Color & Form

Mol Wt

% Metal Content

Stability

Rh–92

Di μ–chlorobis (η4–norbornadiene) dirhodium(I) [RhCl(nbd)]2

mustard yellow crystals

461

44.7

air stable

Rh–93

Di μ–chlorobis (η4–cycloocta–1,5– diene)dirhodium(I); [RhCl(COD)]2

orange crystals

493

41.8

air stable

Rh–95

Acetylacetonato(1,5-cyclooctadiene) rhodium(I) Rh(C8H12)(C5H7O2)

orange crystal

310

33.0

air stable

Rh-96

Bis(cyclooctadiene)rhodium(I) tetrafluoroborate[Rh(C8H12)2]BF4

red-brown solid

406

25.3


Rh–97

Bis(norbornadiene)rhodium(I) tetrafluoroborate [Rh(nbd)2]BF4

dark red solid

374

27.5


Rh–98

Bis(1,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate [Rh(C8H12)2]O3SCF3

dark red crystals

468

22.0

air sensitive

Rh–100

Chloro tris(triphenylphosphine) rhodium(I) [RhCl(PPh3)3] Wilkinson’s catalyst

magenta crystals

925

11.1

slowly decomposes in air

Rh–101

Bromo tris(triphenylphosphine) rhodium(l) [RhBr(PPh3)3]

orange crystals

969

10.6

air sensitive

Rh–105

Hydrido tetrakis(triphenylphosphine) rhodium(ll) [RhH(PPh3)4]

yellow powder

1152

8.9

air sensitive

Rh–110

Rhodium(II) acetate dimer [Rh(OAc)2]2

emerald green powder

442

46.6

air stable

Rh–112

"Rhodium(III) acetate" Hexa(acetato) μ3–oxo tris(aquo) trirhodium acetate [Rh3(OAc)6μ3–O(H2O)3]OAc

brown solid

34–39

air stable

Rh–115

Rhodium(II) octanoate dimer [Rh(C8H15O2)2]2

emerald green powder

778

26.4

air stable

Rh–120

Di μ–chloro dichloro bis (η5–pentamethylcyclopentadienyl) di–rhodium (I); [RhCl2(η5–Cp*)]2

burgundy solid

618

33.3

air stable

Rh–125

Bis(norbornadiene)rhodium trifluoromethanesulfonate [Rh(C7H8)2]BF4

orange solid

436

23.6

stable at 0 deg C

Rh–126

Bis(ethylene)(pentanedionato)rhodium yellow Rh(C2H4)2(C5H7O) solid

257

39.9

air stable

Rh–127

(norbornadiene)(pentanedionato) rhodium Rh(C7H8)(C5H7O)

yellow solid

294

34.9

air stable

FibreCat® 2003

Rh(nbd)2BF4 on triphenylphosphine fibers

orange fiber

3.0-4.0

air sensitive

FibreCat® 2006

Rh(nbd)CI on triphenylphosphine fibers

yellow fiber

2.0-3.5

air sensitive

Rhodium (2–ethylhexanoate) in 2–ethyl hexanol

red/ brown solution

3.0–4.0

air stable

Rhodium(III) chloride hydrate [RhCl3].nH2O

dark red flakes

39–43

air stable

Rhodium(III) iodide [RhI3]

black powder

21.3

air stable but hygroscopic

484


RHODIUM COMPOUNDS

– (CONTINUED)

Solubilities

E.U. Hazard Code


Use and Comments

Catalog No.

v.sl.s most solvents

Xn

12257–42–0 (2355104)

Hydrogenation. Isomerisation Hydroformylation.

Rh–92

sl.s acetone, methanol

Xi

12092–47–6 (2351576)

Hydrogenation. Isomerisation Hydroformylation

Rh–93

s. chloroform

12245-39-5

Hydrogenation (Chiral and non-chiral)

Rh–95

sl s methyl ethyl ketone, dichloromethane

35138-22-8

Hydrogenation, Isomerisation

Rh-96

36620–11–8 (–)

Hydrogenation, Isomerisation

Rh–97

s. chloroform

99326-34-8

Hydrogenation (Chiral and non-chiral)

Rh–98

v.s chloroform sl.s acetone, alcohol v.sl.s diethyl ether, toluene

14694–95–2 (2387445)

Selective Hydrogenation. Decarbonylation. Store under inert gas

Rh–100

Hydrogenation

Rh–101

i. water

CSNYFT

v.s. chloroform sl.s acetone, alcohol v.sl.s diethyl ether, toluene

Xn

14973–89–8 (2390505)


CSNYFT

18284–36–1 (—)

sl.s methanol v.sl.s acetone, acetic acid, chloroform, water

Rh–105

15956–28–2 (2400848)

Cyclopropanation Carbene reactions

Rh–110

s. acetic acid, water

Xi

42204–14–8 (2557079)

Alcohol carbonylation catalyst precursor Available also in solution in acetic acid

Rh–112

sl.s alcohol

CSNYFT

73482–96–9 ( –– )

Cyclopropanation Carbene reactions

Rh–115

s. chloroform, acetone sl.s. THF, methanol i. diethyl ether

CSNYFT

12354–85–7 ( –– )

Hydrogenation Chiral hydrogenation precursor

Rh–120

s. dichloromethane & chloroform

178397-71-2

Chiral Hydrogenation precursor

Rh–125


12082-47-2

Hydrogenation precursor

Rh–126


32354-50-0

Hydrogenation precursor

Rh–127


Selective Hydrogenation

FibreCat® 2003


Selective Hydrogenation

FibreCat® 2006

s. propan–2–ol, acetone

Xn

20845–92–5 (2440791)

Catalyst precursor

s. alcohol, water sl.s acetone

Xn

20765–98–4 * (2331654)

Catalyst precursor

15492–38–3 (2395215)

Alcohol carbonylation catalyst precursor

i. most solvents


83

RUTHENIUM COMPOUNDS Catalog No.

Compound

Color & Form

Mol Wt

% Metal Content

Stability

Ru–41

Dicarbonyldichloro bis(triphenylphosphine) ruthenium(II) [RuCl2(CO)2(PPh3)2]

yellow white crystals

752

13.4

air stable

Ru–42

Carbonylchlorohydrido tris (triphenylphosphine) ruthenium(II) [RuClH(CO)(PPh3)3]

pale yellow crystals

952

10.6

air stable light sensitive

Ru–70

Tris(acetylacetonato) ruthenium(III) [Ru(acac)3]

dark red– brown crystals

398

25.4

air stable

Ru–90

Dichloro (η4–cycloocta–1,5– diene) ruthenium(II) polymer [RuCl2(COD)]n

dark brown powder

38.3

air stable

Ru–91

Bis(2-methylallyl)(1,5cyclooctadiene)ruthenium (II) Ru(C8H12)(C4H7)2

off-white crystals

319

31.6

slowly decomposes in air & moisture as well as at warm conditions

Ru–92

(1,5 cyclooctadiene) ruthenium trifloroacetate [Ru(C8H12) (CF3CO2)]2

yellow powder

870

23.2

air stable

Ru–93

(1,5-cyclooctadiene) ruthenium acetate Ru(C8H12) (CH3CO2)2

yellow powder

327

30.9

air stable

Ru–100

Dichloro tris (triphenylphosphine) ruthenium(II) [RuCl2(PPh3)3]

black solid

958

10.5

air stable

Ru–112

"Ruthenium(III) acetate" Hexa(acetato)μ3–oxo tris (aquo)triruthenium acetate [Ru3(OAc)6μ3–O(H2O)3]OAc

dark green solid

40 – 45

air stable

Ru–120

Tetrachloro bis (η6–p–cymene) diruthenium(II) [RuCl2(η6–C10H14)]2

dark red crystals

612

33.0

air stable

Ru–121

Tetraiodobis (η6 p-cymene) ruthenium(ll) dimer [Rul2(η6-C10H14)]2

brownishyellow solid

978

20.7

stable at room temperature

Ru–130

Tetra (n–propylammonium) perruthenate [NPr4][RuO4], TPAP

very dark green/brown solid

351

28.7


38–43


5 nominal

air stable

3.0-4.5

air stable

Ruthenium(III) chloride hydrate [RuCl3].xH2O

84

FibreCat® 3001

TPAP on triethylamine fibers

FibreCat® 3002

Na2RuO4 on triethylamine fibers

black crystals

grey black fiber


RUTHENIUM COMPOUNDS

Solubilities

E.U. Hazard Code


v.sl.s acetone chloroform, toluene

Xn

14564–35–3 (2386059)

insoluble in most solvents

T

16971–33–8 (2410510)

Disproportionation and silyl transfer. Transfer hydrogenation

Ru–42

s. chloroform sl.s acetone, ethyl acetate, methanol, toluene, water

T

14284–93–6 (2381930)

Hydrogenation

Ru–70

i. most solvents

Xn

50982–13–3 (2568892)

Hydrogenation

Ru–90

i. water

12289-94-0

Chiral Hydrogenation Ru–91 Reduction of CO groups

s. chloroform

133873-70-8


s. chloroform

133519-03-6


v.sl.s acetone, alcohol, chloroform, ethyl acetate, toluene

15529–49–4 (2395697)

Hydrogenation Dehydrogenation Oxidation

Ru–100

55466–76–7 (2596537)

Available also in solution in acetic acid

Ru–112

s. alcohol, chloroform Xn CSNYFT

52462–29–0 ( –– )

Hydrogenation Ru–120 Transfer hydrogenation Chiral hydrogenation precursor

s. chloroform

90614-07-6


114615–82–6 ( –– )

Selective Oxidation

14898–67–0 * (2331675)

Catalyst precursor Available in solution

vs. acetic acid, water sl.s. acetone

s. dichloromethane, acetonitrile i. water

Xi, N

O, Xi CSNYFT

v.s water s. acetone, alcohol sl.s ethyl acetate

Use and Comments

Catalog No. Ru–41

Ru–130


Oxidation

FibreCat® 3001


Oxidation

FibreCat® 3002

* CAS No. refers to a specific hydrate © 2008 Johnson Matthey Plc

85

7. Table: Smopex® Metal Scavenging Products Trade name

Product description

Color Dry cont. Pharma %

Dry cont. Tech %

Funct. Cap. (mmol/g)

Std. Fibre Length (mm)

SMOPEX® Smopex-101

Styrene sulfonic acid grafted polyolefin fiber

Beige to brown

na.

>20

>=2.5

0.3

Smopex-102

Acrylic acid grafted polyolefin fiber

White to beige

>95

>20

>=5

0.3

Smopex-103

Styryl trimethylamine grafted polyolefin fiber

White

na.

>20

>=1.5

0.3

Smopex-105

Vinyl pyridine grafted polyolefin fiber

White to beige to yellow

>95

>20

>=3

0.3

Smopex-110

Styryl-based isothiouronium grafted polyolefin fiber

White

na.

>20

>=1.5

0.3

Smopex-111

Styryl thiol grafted polyolefin fiber


>95

>20

>=2

0.3

Smopex-112

Acrylate based “alpha“-hydroxyl thiol grafted polyoleifin fiber

Off-white to white

na.

>20

>=2.5

0.3

Smopex-234

Mercaptoethylacrylate grafted polyolefin fiber

White to beige

>95

>20

>=2

0.3

Smopex-301

Styryl diphenylphosphine grafted polyolefin fibre


na.

>95

>=0.9

0.3

Note: Pharmaceutical grade Smopex® can be used in API product streams and is supplied dry to conform with limits on residual solvents. Technical grade Smopex® is supplied with variable dry content.

86


8. Glossary of Terms API

The Active Pharmaceutical Ingredient in a drug formulation.

Asymmetric catalysis

A catalytic reaction that produces a chiral molecule by controlling the reaction directly to give single enantiomer yields approaching 100%.

Chemisorption

Adsorption which involves the formation of a chemical bond between the adsorbed atom/molecule and the catalyst surface.

Chemo-catalyst

A man-made material used for catalysis – often containing a PGM as the active component (see definition of PGM).

Chemoselectivity

A reaction is chemoselective when it converts exclusively or preferentially one functional group in the presence of other functional groups.

Chiral

A molecule is chiral if its image and mirror image are not superimposable.

Chiral auxiliary

Chiral compounds such as solvents, additives, reactants which transform prochiral precursors to one of the two enantiomers preferentially.

Chiral molecule

Molecules that are not superimposable with their mirror images (e.g. the right and left hand are mirror images which are not superimposable).

Chiral pool

Naturally occurring chiral molecules, such as carbohydrates, hydroxycarboxylic acids, amino acids, terpenes, alkaloids etc.

Co-catalyst

A substance which adds its own activity (or deactivation) for the considered reaction to the catalyst itself and increases the overall rate of reaction by a synergetic contribution to the basic activity of the main catalyst.

Diastereomers

Structures with more than one chiral center and are not enantiomers. e.g. an R,R structure and an R, S structure. The R centers are identical while the R and S centers are enantiomers.

Enantiomer

The two forms of a chiral molecule. One enantiomer is the mirror image of the other. Distinguished as (R)- and (S)-isomers.

Enantioselective

A reaction or catalyst is called enantioselective if one of the product enantiomers is produced preferentially from a prochiral substrate. Also known as asymmetric.

Enantioselectivity (ee)

The selectivity of an enantioselective reaction is expressed as enantiomeric excess(ee), and is defined as: ee = [R] – [S] x 100% [R] + [S] Also known as optical yield (oy).

Hüttig Temperature

Temperature at which surface atoms become significantly mobile (= 0.3Tm in Kelvin).

Hydrogenolysis

Cleavage of a bond by reaction with molecular hydrogen in the presence of a catalyst.

Intermediates

Chemical substances isolated along the synthesis route to the API (see definition of API).

Ligand

In the context of this handbook, the ligand is a chiral molecule that is attached to the metal atom (which is responsible for the catalytic activity). The presence of the ligand, mainly through its shape and bulk close to the active metal, induces chirality in the product of the catalytic reaction.

Organometellic compound

Molecules containing carbon-metal linkage; a compound containing an alkyl or aryl radical bonded to a metal, such as tetraethyllead, Pb(C2H5)4. However, the definition of organometallic is often broadened to include a variety of ligands such as phosphines, amines, and CO.

% Conversion

The % substrate which is reacted to form reaction products.

% Selectivity

The quantity of desired product expressed as a percentage of the total reaction products.

% Yield

The % conversion x % selectivity, e.g. 90% conversion at 90% selectivity gives 81% yield.

Platinum Group Metals (PGM)

Pd, Pt, Rh, Ru, Ir, Os

Precious Metals (PM)

Pd, Pt, Rh, Ru, Ir, Os, Ag, Au

Prochiral

A molecule is prochiral if it has one symmetry element (plane or inversion centre). Reactions that destroy this symmetry element lead to chiral molecules. Also known as achiral.


87

Glossary of Terms – continued Promoter

Dopants added to catalysts to improve their action – activity, selectivity or stability.

Racemate

A 1:1 mixture of enantiomers.

Regioselectivity

A reaction is regioselective when it takes place at only one of two or more possible functional groups to form just one of two possible isomers.

Substrate

Starting material (or reactant or feedstock) for the catalytic reaction.

Smopex®

Unique scavenging system where metal binding functionality is grafted onto fibres allowing the effective recovery of a range of precious metals.

Tammann temperature

Temperature at which lattices begin to be appreciably mobile (=0.5Tm in Kelvin).

Tm

Melting point in Kelvin.

Turnover number (TON)

The number of molecular reactions or reaction cycles occurring at the reactive centre up to the decay of activity. Specifies the maximum use that can be made of a catalyst for a particular reaction under defined reaction conditions.

VOC

Volatile Organic Compound.

9. Other publications from Johnson Matthey Platinum Platinum is an annual review of world supply and demand for the PGMs, published each year in May. It is updated after 6 months by an Interim Review. The review contains a market summary and outlook, information on supplies, mining and exploration, discussions of the markets for platinum, palladium and other PGMs, information on prices and futures and a breakdown of supply and demand.

Platinum should be read by anyone involved in sourcing decisions involving PGMs. Copies are available free and can be obtained by contacting your local Johnson Matthey office (see section 10).

Platinum Metals Review Platinum Metals Review is a quarterly journal of scientific research on PGMs, published by Johnson Matthey. It covers all areas in which PGMs find application, and not just catalysis. It is freely available on the internet at: http://www.platinum.matthey.com

Those wishing to subscribe to Platinum Metals Review or to submit papers for publication should contact Johnson Matthey offices or the Editor, 40-42 Hatton Garden, London EC1N 8EE; E-mail: [email protected]

Catalytic Reaction Guide The Catalytic Reaction Guide, available free from Johnson Matthey, is a pocket-sized slide chart setting out over 100 reaction types and giving, for each, recommendations covering catalyst type, catalytic metal and reaction conditions. It is very useful as a first point of reference.

New Catalyst Development for Cross-Coupling Reactions Includes examples of catalysts for application in C-C, C-N, C-O, C-S coupling reactions.

88


10. Addresses of Local Offices UNITED KINGDOM Johnson Matthey Plc Orchard Road Royston Hertfordshire SG8 5HE Tel: (44) 176 325 3000 Fax: (44) 176 325 3419 e-mail: [email protected] Johnson Matthey Plc 33 Jeffreys Road Brimsdown Enfield Middlesex EN3 7PW Tel: (44) 208 804 8111 Fax: (44) 208 804 1918 Johnson Matthey Plc Technology Centre Blounts Court Sonning Common Reading Berkshire RG4 9NH Tel: (44) 118 924 2000 Fax: (44) 118 944 2254 Johnson Matthey Plc PO Box 88 Haverton Hill Road Billingham Cleveland TS23 1XN Tel: (44) 1642 525 343 Fax: (44) 1642 522 542 Johnson Matthey Plc 28 Cambridge Science Park Milton Road Cambridge CB4 0FP Tel: (44) 1223 226160 Fax: (44) 1223 438037 AUSTRALIA Johnson Matthey (Aust) Ltd 339 Settlement Road Thomastown Victoria 3074 Tel: (61) 3 9465 2111 Fax: (61) 3 9466 4932


AUSTRIA Johnson Matthey & Co GmbH Steckhovengasse 12 A 1132 Vienna Tel: (43) 187 79890 Fax: (43) 187 798903 BELGIUM S.A. Johnson Matthey N.V. Avenue de Bâle 8 – Bazellaan 8 B – 1140 Brussels Tel: (32) 2 729 07 43 Fax: (32) 2 726 90 61 BRAZIL Johnson Matthey Brazil Rua Dr. Jesuino Maciel, 919 Campo Belo 04615-002 São Paulo – SP Tel: (55) 11 5561 3805 Fax: (55) 11 5561 3098 CHINA Johnson Matthey (Shanghai) Catalyst Co., Ltd. 88 Dong Xing Road Songjiang Industrial Zone Shanghai P.C. 201613 Tel: (86) 21 33528282-6210 Fax: (86) 21 33528728 email: [email protected] CHINA – HONG KONG Johnson Matthey Hong Kong Ltd Suites 2101 CMG Asia Tower The Gateway 15 Canton Road Tsimshatsui Kowloon Tel: (852) 27380327 Fax: (852) 27362345 CZECH and SLOVAC REPUBLICS Johnson Matthey V sadech 4 – Bubenec 160 00 Prague 6 Tel: (420-2) 24321549 (420-2) 24320367 (420-2) 33332384 Fax: (420-2) 24320433 DENMARK Johnson Matthey A/S Frederikssundvej 274D Bronshoj 2700 Copenhagen Tel: (45) 3889 6200 Fax: (45) 3889 6201 89

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90

JAPAN Johnson Matthey Japan Inc The Imperial Tower 14th Floor 1-1-1 Uchisaiwai-cho Chiyoda-ku Tokyo 100-0011 Tel: (81) 3 5511 8551 Fax: (81) 3 5511 8561 email: [email protected] KOREA Johnson Matthey Korea Ltd 6th Floor, Woonam Building 294 Chamsil-dong Songpa-ku Seoul Tel: (82) 2 3431 3816 Fax: (82) 2 3431 3819 PORTUGAL Lusomelt – Fornecimento de bens e Serviços, Lda Rua de Belém, 48 – 2˚ P-1300-085 Lisbon Tel: (351) 21 361 62 10 Fax: (351) 21 363 49 95 RUSSIA Johnson Matthey Moscow Ilyinka 3/8 Building 5, Office 301 Moscow 109012 Russia Tel: 7095 101 2100 Fax: 7095 101 2113 SOUTH AFRICA Johnson Matthey (Pty) Limited Henderson Road South Gerniston Ext 7 Gauteng 1401 Republic of South Africa Tel: (27) 1134 58 500 SPAIN C.J. Chambers Hispania S.L. Apartado 92 08840 Viladecans Barcelona Tel: (34) 607 811 550 Fax: (34) 936 376 913


SWEDEN Please contact our Royston, UK facility for all inquiries SWITZERLAND Johnson Matthey & Brandenberger AG Glattalstrasse 18 CH-8052 Zurich Tel: (41) 1 307 19 19 Fax: (41) 1 307 19 20

USA Johnson Matthey Inc 2001 Nolte Drive West Deptford New Jersey 08066 1727 Tel: (1) 856 384 7000 Fax: (1) 856 384 7282 e-mail: [email protected]

TAIWAN Johnson Matthey Pacific Ltd Taiwan Branch 9F-3, 51 Keelung Road Section 2 Taipei Tel: (886) 2 23786818 Fax: (886) 2 27366558

Information contained in this publication is given in good faith, but Johnson Matthey will accept no liability for any claims made against a customer for any infringement of patent rights, registered or unregistered trademarks (including any copyright therein) or of registered designs or copyright involved in the use, resale or offering for resale of the compound either as sold by Johnson Matthey or otherwise. While Johnson Matthey has taken all reasonable care to ensure the accuracy of the contents of this brochure, it is incumbent on the user to exercise due care and diligence when handling these materials. Johnson Matthey can therefore accept no liability for loss or damage arising from their use. Ref 01.04 / UK © 2008 Johnson Matthey Plc

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PGM Catalyst Handbook USA

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