VULCAN Catalytic Reaction Guide - (106) Heterogeneous Reaction Mechanisms

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VULCAN SYSTEMS
HETEROGENEOUS CATALYST
APPLICATIONS
Catalytic Reaction
Guide: (106)
Heterogeneous Reaction
Mechanisms
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HETEROGENEOUS REACTION CHEMISTRY
CONTENTS
0 HETEROGENEOUS POWDERED CATALYSTS
1 CHOICE OF METAL
2 CHOICE OF SUPPORT
3 MASS TRANSPORT AND REACTOR DESIGN
4 CATALYST DESIGN
5 CATALYST SEPARATION, FILTRATION
6 PROCESS ECONOMICS
6.1 Activated Carbon
6.2 Alumina
6.3 Calcium Carbonate
6.4 Barium Sulfate
6.5 Other Powdered Supports

VULCAN Catalytic Reaction Guide
Chemistry Reactions
1. Hydrogenation 1-55
1.1 C-C Multiple Bonds 1-7
1.2 Aromatic Ring Compounds 8-14
1.3 Carbonyl Compounds 15-25
1.4 Nitro and Nitroso Compounds 28-35
1.5 Halonitroaromatics 36
1.6 Reductive Alkylation's 37 & 38
1.7 Imines 39-41
1.8 Nitriles 42-47
1.9 Oximes 48-49
1.10 Hydrogenolysis 50-54
1.11 Other 55
2. Dehydrogenation 56-60
3. Hydroformylation 61& 62
4. Carbonylation 63-68
5. Decarbonylation 69
6. Hydrosilylation 70 & 71
7. Cross Coupling 72-96
7.1 Heck 72-75
7.2 Suzuki 76
7.3 Buckwald-Hartwig 77 & 78
7.4 Organometallics 79-83
7.5 Sonogashira 84-87
7.6 Other 88-96
8. Cycloproportion 97
9. Selective Oxidation 98-106
9.1 Alcohols to Carbonyls 98-102
9.2 Dihydoxylation of Alkenes 103
9.3 Oxygen Insertion Reactions 104
9.4 Others 105-106
Catalytic Reaction Guide: (106) Heterogeneous Reaction Mechanisms

0 HETEROGENEOUS POWDERED CATALYSTS
Supported precious metal catalysts are used for a variety of reactions
including hydrogenation, dehydrogenation, hydrogenolysis, oxidation,
disproportionation and isomerization. Many important organic
transformations are completed via catalytic hydrogenation. A large number
of these reactions are carried out in the liquid phase, using batch type
slurry processes and a supported heterogeneous platinum group metal
catalyst. Platinum group metal catalysts will reduce most organic
functional groups.
The selection of a catalyst or catalyst system for a new catalytic process
requires many important technical and economic considerations. The
process of selecting a precious metal catalyst can be broken down into
components. Key catalyst properties are high activity, high selectivity, high
recycle capability and filterability. Important process components include
choice of catalytic metal, choice of support, reactor design, heat and mass
transport, catalyst design, catalyst separation, and spent catalyst recovery
and refining.
1 CHOICE OF METAL
Catalyst performance is determined mainly by the precious metal
component. A metal is chosen based both on its ability to complete the
desired reaction and its inability to complete an unwanted reaction.
Palladium is typically the preferred metal for hydrogenation of acetylenes,
olefins, carbonyls in aromatic aldehydes and ketones, aromatic and
aliphatic nitro compounds, reductive alkylation, hydrogenolysis and
hydrodehalogenation reactions. Platinum is typically the preferred metal
for selective hydrogenation of halonitroaromatics and reductive
alkylations. Rhodium is used for the hydrogenation of aromatic rings and
olefins while ruthenium is used for the hydrogenation of aromatic rings and
aliphatic aldehydes and ketones.

2 CHOICE OF SUPPORT
In general, a catalyst support should allow for a high degree of metal
dispersion. The choice of support is largely determined by the nature of
the reaction system. A support should be stable under reaction and
regeneration conditions, and not adversely interact with solvent, reactants
or reaction products. Common powdered supports include activated
carbon, alumina, silica, silica-alumina, carbon black, TiO2, ZrO2, CaCO3,
and BaSO4. The majority of precious metal catalysts are supported on
either carbon or alumina. Information on common powdered supports is
summarized on Page 5.
Figure 1. The Effect of Catalyst Support on Platinum Dispersion
A support can affect catalyst activity, selectivity, recycling, refining,
material handling and reproducibility. Critical properties of a support
include surface area, pore volume, pore size distribution, particle size,
attrition resistance, acidity, basicity, impurity levels, and the ability to
promote metal support interactions. Metal dispersion increases with
support surface area. The effect of increasing support surface area on
metal dispersion for a series of platinum catalysts prepared on activated
carbon, silica, alumina, carbon black, and graphite supports is shown in
Figure 1.

Support porosity affects metal dispersion and distribution, metal sintering
resistance, and intraparticle diffusion of reactants, products and poisons.
Smaller support particle size increases catalytic activity but decreases
filterability. A support should have desirable mechanical properties,
attrition resistance and hardness. An attrition resistant support allows for
multiple catalyst recycling and rapid filtration. Support impurities may
deactivate the metal and enhance catalyst selectivity.
The concentration of precious metal deposited on a support is typically
between 1 and 10 weight percent. Practical metal concentration limits are
between 0.1 and 20 weight percent for activated carbon, and between 0.1
and 5 weight percent for alumina. Relative catalyst activity will generally
increase with decreasing metal concentration at constant metal loading.
3 MASS TRANSPORT AND REACTOR DESIGN
Liquid phase hydrogenations employing heterogeneous catalysts are
multiple phase (gas-liquid-solid) systems containing concentration and
temperature gradients. In order to obtain a true measure of catalytic
performance, heat transfer resistances and mass transfer resistances
need to be understood and minimized. Mass transfer effects can 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 reaction to take place in a multi-phase system,
the following steps must occur: 1) transport of the gaseous reactant into
the liquid phase, 2) transport

Figure 2. Concentration Gradients in Gas/Liquid/Solid Catalytic system
of the dissolved gaseous reactant through the bulk liquid to the surface of
a catalyst particle, 3) transport of the dissolved substrate through the liquid
to the surface of the catalyst particle, 4) diffusion of the reactants into the
pore structure of the catalyst particle, 5) chemisorption of reactants,
chemical reaction, desorption of products, and 6) diffusion of the products
out of the pore structure of the catalyst particle (Figure 2). Detailed rate
expressions have been developed for such systems.
Rate of reaction will be affected by different process variables, depending
on which step is rate-limiting. A reaction controlled by gas-liquid mass
transport, i.e. the rate of mass transport of the gaseous reactant into the
liquid, will be influenced mainly by reactor design, hydrogen pressure, and
agitation rate. A reaction controlled by liquid-solid mass transport, i.e. the
rate of mass transport of either gaseous reactant or substrate from the
bulk liquid to the external surface of the catalyst particle, will be influenced
mainly by gas or substrate concentration, weight of catalyst in reactor,
agitation and catalyst particle size distribution.

A reaction controlled by pore diffusion-chemical reaction, i.e. the rate of
reactant diffusion and chemical reaction within the catalyst particle, will be
influenced mainly by temperature, reactant concentration, percent metal
on the support, number and location of active catalytic sites, catalyst
particle size distribution and pore structure. To evaluate and rank catalysts
in order of intrinsic catalytic activity, it is necessary to operate under
conditions where mass transfer is not rate limiting. A reactor used for
liquid phase hydrogenations should provide for good gas-liquid and liquid-
solid mass transport, heat transport, and uniformly suspend the solid
catalyst.
4 CATALYST DESIGN
The size of the deposited precious metal particulates and their location on
the support material affect the properties and performance of a
heterogeneous catalyst. Increased metal dispersion and decreased metal
particle size generally result in increased catalyst activity. Metal location
and metal dispersion can be controlled during catalyst manufacture. Metal
particulates can be deposited preferentially at the exterior surface of the
support to give what is termed an “eggshell” or “surface-loaded” catalyst.
Catalysts with metal particulates evenly dispersed throughout the support
structure are referred to as having a “standard” or “uniform” metal
distribution (Figure 3).
Figure 3. Schematic of Metal Location

particulates can be deposited preferentially at the exterior surface of the
support to give what is termed an “eggshell” or “surface-loaded” catalyst.
Catalysts with metal particulates evenly dispersed throughout the support
structure are referred to as having a “standard” or “uniform” metal
distribution (Figure 3).
Catalysts are designed with different metal locations for reactions which
take place under different conditions of pressure and temperature.
Hydrogenation reactions are generally first order with respect to hydrogen.
As such, standard catalysts with increased metal dispersions typically
exhibit greater relative activity at high hydrogen pressures. Eggshell
catalysts exhibit higher relative activity at low hydrogen pressures.
Hydrogenation of large molecules is generally carried out using eggshell
catalysts. Variation of metal location can also be used to alter catalyst
selectivity.
Location of catalytic metal deep into the pore structure of the support may
lead to significant reactant pore diffusion limitations. Such catalysts,
however, are generally more poison resistant because catalyst poisons
are typically of high molecular weight, and unlike smaller reactant
molecules, are unable to penetrate into the catalyst pore structure to
deactivate the catalytic metal.
Deposited metal may be either in a reduced or unreduced form.
Unreduced catalysts are readily reduced under the conditions of the
catalytic hydrogenation itself, and are often more active than reduced
catalysts.
Catalysts may be modified with compounds that promote or inhibit certain
reactions. Modifiers affect catalytic activity, selectivity and/or life.

5 CATALYST SEPARATION, FILTRATION
A good powdered catalyst should be easy to separate from the reaction
mixture and final product. Catalyst filtration time should be minimized to
ensure maximum product throughput and production rates. Cycle time
advantages gained from a high activity catalyst can be lost if catalyst
filtration becomes an extended and time consuming step.
A catalyst should exhibit high attrition resistance to reduce catalyst losses
resulting from generation and loss of catalyst “fines”. The generation of
“fines” will also decrease the rate of filtration. There is often a trade-off
between catalyst performance and the rate of catalyst separation. Catalyst
filtration rate and attrition resistance are largely functions of particle size,
particle shape, pore volume, pore size distribution, surface area and raw
material source.
6 PROCESS ECONOMICS
It is important to consider the economic viability of a catalyst and catalytic
process early in the selection process. The economics of using a
supported precious metal catalyst depend critically on catalyst turnover
number, i.e. the amount of product produced per amount of catalyst used,
and on catalytic activity or turnovers per unit time. For supported catalysts
it is often convenient to calculate costs in terms of the weight of product
produced per weight of catalyst used, or catalyst productivity. Catalyst
productivity (P) is defined as:
P = nS/L
where n is the number of times a catalyst is used or recycled, S is reaction
selectivity as a weight percent (weight of desired product produced per
weight of feedstock), and L is catalyst loading as a weight percent (weight
of catalyst used per weight of feedstock). The cost of the catalyst per unit
weight of product can be determined by dividing the total cost of the
catalyst by the catalyst productivity.

Typical catalyst costs include catalyst fabrication, spent catalyst refining or
disposal and precious metal charges. In the case of a catalyst returned for
refining and reclamation of the precious metal, the total metal charges
should include only metal irrecoverably lost during the catalytic process,
the refining process, and due to handling. If the maximum allowable
catalyst cost per unit weight of product is known, one can back calculate
to determine required reaction selectivity and/or the number of catalyst
recycles necessary to make a process economically feasible.
Most of the commonly used catalyst supports, particularly carbon and
alumina, are available in a wide range of particle sizes and surface areas.
6.1 Activated Carbon
Activated carbon powder is used principally as a support for
catalysts in liquid phase reactions. As carbon is derived from
naturally occurring materials, there are many variations, each type
having its own particular physical and chemical properties.
The surface areas of different carbons can range from 500 m2
g-1
to
over 1500 m2
g-1
.
Trace impurities that may be present in certain reaction systems
can occasionally poison catalysts. The high absorptive power of
carbons used as catalyst supports can enable such impurities to be
removed, leading to longer catalyst life and purer products.
6.2 Alumina
Activated alumina powder has a lower surface area than most
carbons, usually in the range of 75 m2
g-1
to 350 m2
g-1
. It is a more
easily characterized and less absorptive material than carbon. It is
also noncombustible. Alumina is used instead of carbon when
excessive loss of expensive reactants or products by absorption
must be prevented. When more than one reaction is possible, a
platinum group metal supported on alumina may prove to be more
selective than the same metal supported on carbon.

6.3 Calcium Carbonate
Calcium carbonate is particularly suitable as a support for
palladium, especially when a selectively poisoned catalyst is
required. The surface area of calcium carbonate is low but it finds
application where a support of low absorption or of a basic nature is
required, for example to prevent the hydrogenolysis of carbon
oxygen bonds.
6.4 Barium Sulfate
Barium sulfate is another low surface area catalyst support. This
support is a dense material and requires powerful agitation of the
reaction system to assure uniform dispersal of the catalyst.
6.5 Other Powdered Supports
Silica is sometimes used when a support of low absorptive capacity
with a neutral, rather than basic or amphoteric character is
required. Silica-alumina can be used when an acidic support is
needed.

Chemistry Reactions
1. Hydrogenation 1-55
1.1 C-C Multiple Bonds 1-7
1.2 Aromatic Ring Compounds 8-14
1.3 Carbonyl Compounds 15-25
1.4 Nitro and Nitroso Compounds 28-35
1.5 Halonitroaromatics 36
1.6 Reductive Alkylation's 37 & 38
1.7 Imines 39-41
1.8 Nitriles 42-47
1.9 Oximes 48-49
1.10 Hydrogenolysis 50-54
1.11 Other 55
2. Dehydrogenation 56-60
3. Hydroformylation 61& 62
4. Carbonylation 63-68
5. Decarbonylation 69
6. Hydrosilylation 70 & 71
7. Cross Coupling 72-96
7.1 Heck 72-75
7.2 Suzuki 76
7.3 Buckwald-Hartwig 77 & 78
7.4 Organometallics 79-83
7.5 Sonogashira 84-87
7.6 Other 88-96
8. Cycloproportion 97
9. Selective Oxidation 98-106
9.1 Alcohols to Carbonyls 98-102
9.2 Dihydoxylation of Alkenes 103
9.3 Oxygen Insertion Reactions 104
9.4 Others 105-106

Reactant Product Metal Support Reaction
Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd > Pt > Rh
Rh = Ru = Ir
C > Al2O3 =
BaSO4 BaSO4 =
CaCO3
5-100 3-10 None or low
polarity solvent
Rh, Pt or Ru used for
stereoselective application. Pd
may cause isomerization
Pd C > Al203 20-100 1-10 None or low
polarity solvent
Pd very active under mild
conditions.
Pd CaCO3 > C
C > BaSO4
5-50 1-3 Low Polarity
Solvent
Doped Catalyst (Lindlar) under
mild conditions
Pt > Rh > Pd
Pd = Ru
C > AlO3 5-100 1-10 Neutral or acidic for
Cl, Br Neutral or
basic for others
X = OR, OCOR, Cl, Br, NHR, No
base with halogens; no acid with
others
Pd > Ru >Pt Al2O3 > C
C > CaCO3
5-100 1-3 None or a Polar
solvent
Pd most common catalyst.
Ir-40; Rh-93,
100; Ru-100
None 20-80 1-5 Various Least hindered double bond
reduced. Asymmetric
hydrogenation with chiral ligands
Pt > Pd > Rh C > Al2O3 50-150 3-10 None or low
polarity solvent
Pd may give disproportionation
1.1 C-C Multiple Bonds

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Rh> Pt Pt =
Ru > Pd
C > Al2O3 50-150 3-50 No solvent Rh active under mild conditions.
Pd >> Rh Al203 > C 100-150Ɨ >
150Ŧ
1-50 None or low
polarity solvent
Basic promoters enhance activity /
selectivity.
Rh > Pd >
Ru
C > Al2O3 5-150 1-50 None or low
polarity solvent
Rh preferred - no selectivity
problems.
Pt >> Ir C >> Al2O3 5-150 1-50 Acidic solvent Acetic acid or alcohol/HCl
preferred.
Rh > Ru C > Al2O3 100-150 3-50 Acetic acid Pd most common catalyst.
Rh > Ru > Pt C > Al2O3 50-150 3-10 for Rh
> 50 for Ru
Low polarity
solvent
X = OH, OR, OCOR, NH2, NHR,
Rh preferred - no hydrogenolysis.
Product Reactant
Pt = Rh C >> Al2O3 30-150 3-50 None or alcohol Acetic acid may enhance activity.
1.2 Aromatic Ring Compounds

Product Reactant Metal Support Reaction
Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Ru > Pt C > Al2O3 5-100 1-50 Low polarity
solvent
Fe2+ or Sn2+ salts promote Pt.
Water promotes Ru.
Pt C > CaCO3 5-100 1-20 Non-polar or low
polarity solvent
Modifiers required, e.g. Base, Fe2+
or Zn2+ salts.
Pd C >> Al2O3 5-100 1-10 Neutral solvent Acid causes loss of OH
Ru > Rh > Pt C >> Al2O3 50-150 1-50 Polar solvent (e.g.
water)
Ru requires high pressure.
Rh -40, 92, 93,
100 Ru-42,
100
None 25-110 1-200 Various Asymmetric Hydrogenation possible
with chiral ligands. Reduction of the
ketone also possible via
hydrosilation.
Pt C >> Al2O3 5-150 1-10 Low polarity
solvent
Modifiers required, e.g. Base, Fe2+
or Zn2+ salts.
Pd C >> Al2O3 5-50 1-10 Low polarity
solvent
Acid promotes hydrogenolysis of OH
Rh >> Ru C >> Al2O3 5-100 1-50 Low polarity or
neutral solvent
Ru requires high temperaturesand
pressures.
Pd C > Al2O3 5-100 1-10 Acidic solvent Promoted by strong acids.
Rh/Mo or
Rh/Re
Al2O3 150-200 80-100 Ethers Works best with 2o or 3o amides.
Poor for 1o amides.
Ru C > Al2O3 200-280 200-300 None or an
alcoholic solvent
Promoted by Sn.
1.3 Carbonyl Compounds

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd = Pt > Rh C 50-100 3-50 Low polarity
solvent
Bases often inhibit reaction. Prduct
amine may poison catalyst.
Reactant Product
Pd C >> Al2O3 5-100 1-10 Low polarity
solvent
Acids normally prevent dimer
formation.
Pd = Pt C > Al2O3 5-50 1-5 Various Neutral conditions
Pt > Pd = Ir CaCO3 > BaSO4
BaSO4 > Al2O3
5-100 1-5 Various Use N- or S- compounds as
moderators
Pt C 50-150 <1-3 Dilute H2SO4 The Benner process.
Pd > Pt > Ru C >> Al2O3 50-100 1-10 Polar or low
polarity solvent
In presence of base.
Pd >> Pt C 5-100 1-10 Low polarity
solvent
Acetic acid/mineral acid solvent
preferred
Pd = Pt C > Al2O3 5-50 1-10 Various Neutral or mildly acidic conditions
preferred
Pd > Pt > Rh C 5-100 1-10 Various Mineralacid/acetic acid or mineral
acid/alcohol
Pd >>Rh C >> Al2O3 5-100 1-10 Polar or low
polarity solvent
Many dissolved salts improve rate.
1.4 Nitro & Nitroso

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pt >> Rh = Pd C 5-100 1-10 Low polarity
solvent
X = halogen F >> Cl > Br > I.
Stability to hydrogenolysis
1.5 Halonitroaromatics

Metal Support Reaction
Temp.
Reaction
Pressure
Solvents COMMENTS
Reactant Product (deg. C) (BAR)
Pd = Pt C >> Al2O3 50-150 3-50 Low polarity
solvent
Schiff base formulation catalysed
by acid.
Pd = Pt C >> Al203 50-150 1-50 None or low
polarity solvent
Often add ketone and more
catalyst after nitro reduction
1.6 Reductive Alkylations

Temp.
Reaction
Pressure
Solvents COMMENTS
Pt C >> Al2O3 50-150 3-50 Low polarity
solvent
Acidic conditions favored.
Product Reactant
Ir-93, Rh-93,
100, Ru-100
None 25-170 1-200 DMF, Ethanol Asymmetric hydrogenation possible
with chiral ligands.
Pt C 50-100 3-50 Various Acetic acid or ethanol best.
1.7 Imines

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd = Rh > Pt C > > Al2O3 50-100 1-10 Acidic solvent or
additionof excess
ammonia.
Best Solvent is alcohol plus 1-2
equivalents of HCl or H2SO4
Rh C > > Al2O3 5-100 '1-10 Neutral solvent Rh gives good selectivity.
Pd > > Pt C >> Al2O3 5-100 1-10 Neutral solvent Pd gives best selectivity.
Pd C > Al2O3 5-100 1-10 Alcohol/acid or acetic
acid
Best solvents - acetic acid or alcohol
+ HCl or H2SO4
Pt > Pd C >> Al2O3 5-100 1-10 Low polarity solvent Use Neutral low polar solvents
Pd C 5-100 1-10 Alcohol with water &
acid
Imine intermediate hydrolyzed by
water.
1.8 Nitriles

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Rh >> Pd C > > Al2O3 5-100 1-10 Various Alcohol + Acid or ammonia to
minimize coupling reactions
Pd > > Rh C >> Al2O3 5-100 1-10 Acidic solvent Mineral acid/acetic acid or mineral
acid/alcohol
1.9 Oximes

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd C > > Al2O3 5-100 1-10 Low polarity solvent X = Cl, Br or I. Basic conditions
favored.
Pd C >BaSO4 5-50 1-3 Nonpolar solvent Reflux. Use N- or S- compounds as
modifiers + halogen aceptors.
Ru C > Al2O3 200-280 200-300 None or an alcoholic
solvent
Promoted by Sn.
Reactant Product
Pd > Pt
Pt = Ru > Rh
C > Al2O3
Al2O3 = CaCO3
50-150 3-50 Basic solvent for Cl &
Br; acidic for others
X = OR, OCOR, Cl, Br, NHR. With
halogens use alcoholic KOH or
NaOH, with others use alcoholic HCl
or acetic acid.
Pd C >> Al2O3 50-150 1-10 Acidic or neutral
solvent
X = OR, OCOR, Cl, Br, NHR. THF
Best for C-O cleavage. Aliphatic
carbonyls best for C-N cleavage.
1.10 Hydrogenolysis

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd C >> Al2O3 50-100 3-50 Acidic solvent Organic base may promote
selectivity.
1.11 Other

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd > Pt C >200 > 1 = 1 Various high
boiling point
solvents
Remove liberated H2 by N2 purge or
H2 acceptor in liquid phase.
Pd > Pt C > Al2O3 50-300 < 1 No solvent Pd is the only active catalyst.
Pd-62, 111 None 40-80 1-5 Methanol/water E = O, NH. Perform in presence of
reoxidant, e.g.Cu(Oac)2/O2.
Pd C 180-250 > 1 = 1 High Boiling Use dinitrotoluene as H2 acceptor.
Pd C > Al2O3 180-250 < 1 High Boiling
2. Dehydrogenation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Rh-42, 43, 50,
112
None 50-150 10-50 Aldehydes or
toluene
Higher normal to iso-aldehyde ratios
obtainable with Rh than with Co.
PPh3:Rh > 50:1 = 50:1
Pd-100, 111 None 50-150 10-50 Various. Base
promoted
X = Br, I R = aryl, benzyl, vinyl
Base promoted
3. Hydroformylation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pd-100, 101; Pt-100;
Rh-40, 112
None 50-150 10-50 Alcohol Use SnCl2 promoter for Pt and Pd.
Pt active for terminal alkenes only.
Pd-92, 100, 111 None 50-150 1-20 Various. Base
promoted
E = O, NH X = Br, I R = aryl,
benzyl, vinyl Base promoted
Pd-100, Rh-112,
RhI3
None 100-150 1-50 Carboxylic acids
(Rh) or ketones
(pd)
Iodide promotes Rh for !o alcohols.
Acidss promote Pd for 2o alcohols.
Product Reactant
Pd-100, 101, 111 None 25-100 1-10 Various Organic base such as Et3N, Bu3N
or inorganic bases such as
K2CO3. Ligand such as PPh3 also
required if Pd-111 is used.
Pd-100, 101 None 25-100 1-10 DMF Organic base such as Et3N, Bu3N
or inorganic bases such as
Pd-100, 111 None 50-150 1-20 Alcohol R = aryl Cu or Co promoted
4. Carbonylation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Rh-100 None 50-150 ca. 1 Various Also possible to decarbonylate
some acyl alcohols.
5. Decarbonylation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Pt-92, 96, 112,
114
H2[PtCl6]
None 25-75 Ambient None,
hydrocarbons
Rh-93, 100 None 25 Ambient MeCN Z isomer obtained with EtOH or
propan-2-ol. PPh3 also requiredas
ligand when Rh-93 used.
6. Hydrosilylation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Pd-62, 92, 100, 101,
111
None -10-80 ca. 1 Various M = Li, Mg, Zn, Zr, B, Al, Sn, Si,
Ge, Hg, Ti, Cu, Ni.
Pd-92, 100, 111 None 50-150 1-3 Amine or toluene X = Br, I, Otf. Base required as HX
Scavenger.
Pd-92, 111 None 25-100 - Various Organic and inorganic bases can
be used. Various ligands can be
Pd-62, 92,101, 106,
111
None 25-100 - Various Phosphineligand required where
Pd-62, 92, 111 are used. Base
required.
7.1 Heck

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Pd-92, 101, 111 None 25-100 - Various Base required, generally inorganic.
Various ligands can be used in
conjunction with Pd precursor e.g.
PPh3, P(o-to)3, t-Bu3P.
7.2 Suzuki

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Pd-92,111, 106 None 80-100 - THF, toluene Base required, t-BuONa or
Cs2CO3. Ligand such as P(o-to)3,
t-Bu3P, BINAP required when Pd-
92 or Pd-111 used.
Pd-92, 111 None 80-100 - toluene Specialist ligand required. Base
such as K3PO4, NaOH required
when R'OH used as substrate.
7.3 Buckwald-Hartwig

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Reactant Product
Pd-100, 101, 103,
106
None 25-Reflux - THF, dioxane
Various Pd
precursors
None 25-100 - Various Base may be required in some
instances. M = Li, Mg, Zn, B, Al, Si, Hg
Pd-92, 111 None 25-100 - DMSO Pd-111 usually used in conjunction with
BINAP, Pd-92 in conjunction with dppf.
T-BuONa may be required.
Pd-62, 92, 100, 101,
111
None 25-100 - DMF, dioxane,
toluene, THF, NMP
Cu(I) may be needed as a co-catalyst.
Pd-92, 100, 101,
103, 105, 106,
None 25-100 - Various M = Li, MgX, ZnX, SnR3
7.4 Organometallics

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Reactant Product
Pd-100, 101 None 25-reflux - DMF, THF Addition of CuI as a co-catalyst
activates acetylene by formation of
copper acetylide. Organic base e.g.,
NR3 usually used.
Pd-111 None 25-100 - DMF Base required K2CO3 or Na2CO3,
Bu4NClalso required. Reaction
performed under phase transfer
conditions, hence the need for
B 4NCl
Pd-100 None 65 - THF Use Cul as additive.
Pd-62, 100, 111 None 25-reflux - NHEt2, NEt3 The addition of Cul as co-catalyst
activates the acetylene by formation of
a copper acetylide. Poor results are
obtained without Cul. The use of
amines is critical.
7.5 Sonogashira

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Reactant Product
Pd-62, 111 None 40-80 1-5 Methanol/water E = O, NH, Perform in presence of
reoxidant, e.g., Cu(Oac)2/O2
Pd-92, 111 None 25-100 - Toluene, THF,
dioxane
Base required NaOtBu, K3PO4
generally used Specialist ligand
Ru-120 + prop-2-yn-1-
ol, NaPF6 + P(Cy)3
None 25-80 Ambient Toluene,
dichloromethane
Pd-62 None 65 - THF Use LiCl as additive. Use of a mild
reoxidant such as benzoquinone is
required.
Pd-62, PdCl2 None 65 - THF Use NaCO3 or NaH as additives.
Product Reactant
PdCl2 None 80 - Acetonitrile
Pd-111, PdCl2 None 25-65 - THF Lithiation of the alcohol using n-
BuLi in THFis requried as the initial
step. Palladium precursor used in
conjunction with PPh3.
Pd-92,101,111 None 25-65 - THF Ligand required when using Pd-92
or Pd-111. Asymetric induction can
be achieved using a chiral ligand.
Pd-111 None 100 - DMF Base required, NBu4Cl. Ligand
such as PPh3 is also required.
7.6 Other

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Pd-111; Rh-110, 115 None 20-50 ca. 1 Various Asymetric cyclopropanation
possible with chiral ligands.
8. Cyclopropanation

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Ru-100, 130 None 25-110 Ambient MeCN, PhCl,
toluene
dichloromethane
N-methyl-morpholine-N-oxide or
oxygen used as co-oxidant.
TEMPO also required as ligand
when Ru-100 used.
Pt, Pd, Ru C, Al2O3 30-70 1-3 Toluene,
hydrocarbons
Use air as oxidant.
Pt, Pd, Ru C, Al2O3 '30-70 1-3 Toluene,
hydrocarbons
Use air as oxidant.
Ru-100, 130 None 25-110 Ambient MeCN, PhCl,
toluene
dichloromethane
N-Methyl-morpholine-N-oxide
oroxygen used as co-catalyst.
TEMPO also required as ligand
when Ru-100 used.
Pt > Pd C 40-60 1-5 Aqueous Basic pH (8-10) essential.
9.1 Alcohols to Carbonyls

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
OsO4/
K2[OsO2(OH)4]
None 0-50 ca. 1 t-butanol, water,
THF
Oxidants such as N-
methylmorphine N-oxide or
K3Fe(CN)6 preferred. Asymetric
hydroxylation possible with chiral
ligands.
9.2 Dihydroxylation of Alkenes

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
Pd-111 None 20-50 1-5 Acetic acid or
alcohol
O2 or H2O2 used as oxidant.
Cu2+ co-catalyst.
9.3 Oxygen Insertion Reactions

Temp.
Reaction
Pressure
Solvents COMMENTS
(deg. C) (BAR)
Product Reactant
RuCl3, Ru-100 None 25-70 ca. 1 Various H2O2 or NaOCl oxidant.
PdCl2 None - - Water, DMF. Aq.
HCl
Use CuCl2/O2 as additives.
9.4 Other

VULCAN Catalytic Reaction Guide - (106) Heterogeneous Reaction Mechanisms

VULCAN Catalytic Reaction Guide - (106) Heterogeneous Reaction Mechanisms

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VULCAN Catalytic Reaction Guide - (106) Heterogeneous Reaction Mechanisms