This invention relates to a catalyst, to a method of preparing a catalyst and in
particular to a method of preparing a microencapsulated catalyst.
WO03/006151 describes an encapsulated catalyst system and methods for the
production of these encapsulated catalysts. One particular system described in
W003/006151 concerns palladium based encapsulated catalysts which find use in
coupling reactions. These palladium based encapsulated catalysts are most often
derived by micro-encapsulation of palladium acetate. It has recently been found that by
carrying out the micro-encapsulation of the metal catalyst in the presence of a ligand that
metal catalysts losses during the encapsulation process may be ameliorated.
According to a first aspect of the present invention there is provided a process for
the preparation of a microencapsulated catalyst-ligand system which comprises forming a
microcapsule shell by interfacial polymerisation in the presence of a catalyst and a ligand.
It is preferred that the catalyst is an inorganic catalyst and in particular a transition
metal catalyst. The term transition metal catalyst as used herein includes (a) the
transition metal itself, normally in finely divided or colloidal form, (b) a complex of a
transition metal or (c) a compound containing a transition metal. If desired a prs-cursor
for the catalyst may be microencapsulated within the polymer microcapsule shell and
subsequently converted to the catalyst, for example by heating. The term catalyst thus
also includes a catalyst pre-cursor.
Preferred transition metals on which the catalysts for use in the present invention
may be based include platinum, palladium, osmium, ruthenium, rhodium, iridium, rhenium,
scandium, cerium, samarium, yttrium, ytterbium, lutetium, cobalt, titanium, chromium,
copper, iron, nickel, manganese, tin, mercury, silver, gold, zinc, vanadium, tungsten and
molybdenum. Highly preferred transition metals on which the catalysts for use in the
present invention may be based include osmium, ruthenium, rhodium, titanium, vanadium
and chromium, and especially palladium. Air sensitive catalysts may be handled using
conventional techniques to exclude air.
Palladium in a variety of forms may be microencapsulated according to the
present invention and is useful as a catalyst for a wide range of reactions.
Preferably palladium is used directly in the form of an organic solvent soluble form
and is most preferably palladium acetate. Thus for example palladium acetate may be
suspended or more preferably dissolved in a suitable solvent such as a hydrocarbon
solvent or a chlorinated hydrocarbon solvent and the resultant solution may be
microencapsulated according to the present invention. Chloroform is a preferred solvent
for use in the microencapsulation of palladium acetate.
According to literature sources palladium acetate decomposes to the metal under
the action of heat Catalysts of the present invention derived from palladium acetate have
proved to be effective, although it is not presently known whether palladium is present in
the form of the metal or remains as palladium acetate.
It is preferred that the iigand is an organic ligand. Organic ligands typically include
organic moieties which comprise at least one functional group or hetroatom which can
coordinate to the metal atoms of the catalyst. Organic ligands include mono-functional,
bi-functional and multi-function ligands. Mono-fuctional ligands comprise only one
functional group or hetroatom which can coordinate to a metal. Bi-functional ligands or
multi-function ligands comprise more than one functional group or hetroatom which can
coordinate to a metal.
Preferably, the organic ligand is soluble in organic solvents.
Preferably, the organic ligand is an organic moiety comprising one or more
hetroatoms selected from N, O, P and S.
More preferably, the organic ligand is an organic moiety comprising one or more P
atoms.
Highly preferred are organic ligands of formula (1):
R1, R and RJ are each independently an optionally substituted hydrocarbyl
group, an optionally substituted hydrocarbyloxy group, or an optionally substituted
hetrocyclyl group or one or more of R1 & R2, R1 & R3, R2 & R3 optionally being linked in
such a way as to form an optionally substituted ring(s),
Hydrocarbyl groups which may be represented by R1"3 independently include alkyl,
aikenyl and aryl groups, and any combination thereof, such as aralkyl and alkaryl, for
example benzyl groups.
Alkyl groups which may be represented by R1"3 include linear and branched alkyl
groups comprising up to 20 carbon atoms, particularly from 1 to 7 carbon atoms and
preferably from 1 to 5 carbon atoms. When the alkyl groups are branched, the groups
often comprising up to 10 branch chain carbon atoms, preferably up to 4 branch chain
atoms. In certain embodiments, the alkyl group may be cyclic, commonly comprising
from 3 to 10 carbon atoms in the largest ring and optionally featuring one or more
bridging rings. Examples of alkyl groups which may be represented by R1"3 include
methyl, ethyl, propyl, 2-propyl, butyl, 2-butyl, t-butyl and cyclohexyl groups.
Aikenyl groups which may be represented by R1"3 include C2.2o, and preferably C2-e
aikenyl groups. One or more carbon - carbon double bonds may be present. The aikenyl
group may carry one or more substituents, particularly phenyl substituents. Examples of
aikenyl groups include vinyl, styryl and indenyl groups.
Aryl groups which may be represented by R1"3 may contain 1 ring or 2 or more
fused rings which may include cycloalkyl, aryl or heterocyclic rings. Examples of aryl
groups which may be represented by R1"3 include phenyl, tolyl, fluorophenyl, chlorophenyl,
bromophenyl, trifluoromethylphenyl, anisyl, naphthyl and ferrocenyl groups.
Heterocyclic groups which may be represented by R1"3 independently include
aromatic, saturated and partially unsaturated ring systems and may constitute 1 ring or 2
or more fused rings which may include cycloalkyl, aryl or heterocyclic rings. The
heterocyclic group will contain at least one heterocyclic ring, the largest of which will
commonly comprise from 3 to 7 ring atoms in which at least one atom is carbon and at
least one atom is any of N, O, S or P. Examples of heterocyclic groups which may be
represented by R1"3 include pyridyl, pyrimidyl, pyrrolyl, thiophenyl, furanyl, indolyl, quinolyl,
isoquinolyl, imidazoyl and triazoyl groups.
When any of R1"3 is a substituted hydrocarbyl or heterocyclic group, the
substituent(s) should be selected such so as not to adversely affect the activity of the
catalyst. Optional substituents include halogen, cyano, nitro, hydroxy, amino, thiol, acyl,
hydrocarbyl, perhalogentated hydrocarbyl, heterocyclyl, hydrocarbyloxy, mono or dihydrocarbylamino,
hydrocarbylthio, esters, carboxylate, carbonates, amides, sulphonate,
sulphonyl and sulphonamido groups wherein the hydrocarbyl groups are as defined for R1
above. One or more substituents may be present, and includes when any of R1, R2 or R3
is a perhalogenated hydrocarbyl group. Examples of perhalogenated alkyl groups which
may be represented by R1"3 include -CF3 and -C2F5.
When any of R1 & R2, R1 & R3, R2 & R3 are linked in such a way that when taken
together with the phosphorus atom to which they are attached that a ring is formed, it is
preferred that these rings be 5, 6 or 7 membered rings.
Examples of phosphorus based ligands of formula (1) include PMe2CF3, P(OEt)3,
P(Et)3. P(Bu)3, P(cyclohexyl)3> PPhEt2, PPh2Me, PPh3, P(CH2Ph)3, P(CH2Ph)Ph2>
P(p-tolyl)3, P(o-C6H4OMe)3, P(OPh)3, P(O-p-tolyl)3, P(p-C6H4OMe)3, P(o-tolyl)3,
P(m-tolyl)3, PMe3, PPhMe2, PPh2Et, P(/-Pr)3, P(f-Bu)3, PPhCH2Ph, PPh2OEt, PPh(OEt)2,
P(O-o-tolyl)3, P(OMe)3, P(n-Pr)3, PPh(/-Pr)2, PPh2(/-Pr), PPhBu2, PPh2Bu, P(/-Bu)3,
PPh(cyclohexyl)2, PPh2(cyclohexyl), P(CH2Ph)2Et, P(CH2Ph)Et2, P(C6F5)Ph2, P(p-C6H4F)3,
P(p-C6H4CI)3, P(C6F5)2Ph, P(o-C6H4F)3, P(o-C6H4CI)3, P(2-furanyl)3, P(2-thienyl)3,
P(n-octyl)3, P(p-C6H4N02)3,
Preferably organic ligands are selected so as not to adversely effect the properties
of the catalyst. More preferably organic ligands are selected to enhance catalytic activity.
For example, cross couplings traditionally employ phosphines, and the more electron rich
the ligand is, the better the activity usually is. However, electron rich ligands tend to show
increased air sensitivity. A good compromise, balancing increased activity and increased
air sensitivity is either to incorporate three bulky alkyl groups, for example as in
butyl)phoshine (2), or to position an additional donor grouping within proximity of the
triaryl phoshine moiety, for example as in alaphos (3), or a combination of these
approaches, for example as in (4).
The ligand may also be selected on the basis of the reactions the catalyst is
adapted to enhance. For example, Ligand (2) may be suited where the catalyst is for use
in Stille, Suzuki, Sonogashira and Negishi reactions. Ligand (3) may be suited where the
catalyst is for use in the coupling of alkynyl-Grignard reagents. Ligand (4) may be suited
where the catalyst is for use in Suzuki coupling and C-N bond forming reactions.
Trialkylphosphites may be suited where the catalyst is for use in Suzuki couplings of
aromatic chlorides and bromides. In recent years air stable and water tolerant
heterocyclic carbenes such as imidazolium salt (5) have been developed as a
phosphorous free ligand class and may be suited where the catalyst is for use in the
coupling of Grignard reagents, alkyltrimethoxy silanes, organostannanes, and
organoboranes. Another phoshorus free ligand class that may be suited where the
catalyst is for use in Suzuki couplings is the 2,3-diaza-1-3-butadienes.
A recent summary in which cross coupling reactions are discussed, Metal-
Catalysed Cross Coupling reactions; Diedrich, F.; Stang, P.J., Eds.; Wiley-VCH:
Weinheim, 1998, provides a useful a guide to the selection of ligands to enhance catalytic
activity, which is herein incorporated by reference.
It is understood that one or more ligands and/or one or more catalysts may be
employed in the process of the present invention. Where multiple ligands and/or multiple
catalysts are employed, each independently may be selected for the ability to enhance or
catalyse the same or similar reaction types, or for the ability to enhance or catalyse
different reaction types.
There are various types of interfacial polymerisation techniques but all involve
reaction at the interface of a dispersed phase and a continuous phase in an emulsion
system. Typically the dispersed phase is an oil phase and the continuous phase is an
aqueous phase but interfacial polymerisation reactions at the interface of a continuous oil
phase and a dispersed aqueous phase are also possible. Thus for example an oil or
organic phase is dispersed into a continuous aqueous phase comprising water and a
surface-active agent. The organic phase is dispersed as discrete droplets throughout the
aqueous phase by means of emulsification, with an interface between the discrete
organic phase droplets and the surrounding continuous aqueous phase solution being
formed. Polymerisation at this interface forms the microcapsule shell surrounding the
dispersed phase droplets.
In one type of interfacial condensation polymerisation microencapsulation process,
monomers contained in the oil and aqueous phase respectively are brought together at
the oil/water interface where they react by condensation to form the microcapsule wall. In
another type of polymerisation reaction, the in situ interfacial condensation polymerisation
reaction, all of the wall-forming monomers are contained in the oil phase. In situ
condensation of the wall-forming materials and curing of the polymers at the organicaqueous
phase interface may be initiated by heating the emulsion to a temperature of
between about 20°C to about 100°C and optionally adjusting the pH. The heating occurs
for a sufficient period of time to allow substantial completion of in situ condensation of the
prepolymers to convert the organic droplets to capsules consisting of solid permeable
polymer shells entrapping the organic core materials.
One type of microcapsule prepared by in situ condensation and known in the art is
exemplified in U.S. patents 4,956,129 and 5,332,584. These microcapsules, commonly
termed "aminoplast" microcapsules, are prepared by the self-condensation and/or crosslinking
of etherified urea-formaldehyde resins or prepolymers in which from about 50 to
about 98% of the methylol groups have been etherified with a C4-C10 alcohol (preferably
n-butanol). The prepolymer is added to or included in the organic phase of an oil/water
emulsion. Self-condensation of the prepolymer takes place optionally under the action of
heat at low pH. To form the microcapsules, the temperature of the two-phase emulsion is
raised to a value of from about 20°C to about 90°C, preferably from about 40°C to about
90°C, most preferably from about 40°C to about 60°C. Depending on the system, the pH
value may be adjusted to an appropriate level. For the purpose of this invention a pH of
about 1.5 to 3 is appropriate:
As described in U.S. Pat. No. 4,285,720 the prepolymers most suitable for use in
this invention are partially etherified urea-formadehyde prepolymers with a high degree of
solubility in organic phase and a low solubility in water. Etherified urea-formaldehyde
prepolymers are commercially available in alcohol or in a mixture of alcohol and xylene.
Examples of preferred commercially available prepolymers include the Beetle etherified
urea resins manufactured by BIP (e.g. BE607, BE610, BE660, BE676) or the Dynomin Nbutylated
urea resins from Dyno Cyanamid (e.g. Dynomin UB-24-BX, UB-90-BX etc.).
Acid polymerisation catalysts capable of enhancing the microcapsule formation
can be placed in either the aqueous or the organic phase. Acid polymerisation catalysts
are generally used when the core material is too hydrophobic, since they serve to attract
protons towards the organic phase. Any water soluble acid polymerisation catalysts
which has a high affinity for the organic phase can be used. Carboxylic and sulphonic
acids are particularly useful.
One further type of microcapsule prepared by in situ condensation and found in
the art, as exemplified in U.S. Patent No. 4,285,720 is a polyurea microcapsule which
involves the use of at least one polyisocyanate such as polymethylene
polyphenyleneisocyanate (PMPPI) and/or tolylene diisocyanate (TDI) as the wall-forming
material. In the creation of polyurea microcapsules, the wall-forming reaction is generally
initiated by heating the emulsion to an elevated temperature at which point a proportion of
the isocyanate groups are hydrolyzed at the interface to form amines, which in turn react
with unhydrolyzed isocyanate groups to form the polyurea microcapsule wall. During the
hydrolysis of the isocyanate monomer, carbon dioxide is liberated. The addition of no
other reactant is required once the dispersion establishing droplets of the organic phase
within a continuous liquid phase, i.e., aqueous phase, has been accomplished.
Thereafter, and preferably with moderate agitation of the dispersion, the formation of the
polyurea microcapsule can be brought about by heating the continuous liquid phase or by
introducing a polymerisation catalyst such as an alkyl tin or a tertiary amine capable of
increasing the rate of isocyanate hydrolysis.
The amount of the organic phase may vary from about 1% to about 75% by
volume of the aqueous phase present in the reaction vessel. The preferred amount of
organic phase is about 10 percent to about 50 percent by volume. The organic
polyisocyanates used in this process includes both aromatic and aliphatic mono and poly
functional isocyanates. Examples of suitable aromatic diisocyantes and other
polyisocyantes include the following: 1-chloro-2,4-phenylene diisocyante, m-phenylene
diisocyante (and its hydrogenated derivative), p-phenylene diisocyante (and its
hydrogenated derivative), 4,4'-methylenebis (phenyl isocyanate), 2,4-tolylene
diisocyanate, tolylene diisocyanate (60% 2,4-isomer, 40% 2,6-isomer), 2,6-tolylene
diisocyante, 3,3'-dimethyl-4,4'-biphenylene diisocyante, 4,4'-methylenebis(2-methylphenyl
isocyanate), 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 2,2',5,5'-tetramethyl-4,4'-
biphenylene diisocyanate, 80% 2,4- and 20% 2,6-isomer of tolylene diisocyanate,
polymethylene polyphenylisocyante (PMPPI), 1,6-hexamethylene diisocyanate,
isophorone diisocyanate, tetramethylxylene diisocyanate and 1,5-naphthy!er.3
diisocyanate, hydrophilic alipnatic polyisocyanates based on hexamethylene diisocyanate
(e.g. Bayhydur 3100, Baynydur VP LS2319 and Bayhydur VP LS2336) and hydrophilic
aliphatic polyisocyanates based on isophorone diisocyanate (e.g. Bayhydur VP LS2150/1)
It may be desirable to use combinations of the above mentioned polyisocyantes.
Preferred polyisocyantes are polymethylene polyphenylisocyante (PMPPI) and mixtures
of polymethylene polyphenylisocyante (PMPPI) with tolylene diisocyanate or other
difunctional aromatic or aliphatic isocyantes.
One further class of polymer precursors consists of a primarily oil-soluble
component and a primarily water-soluble component which react together to undergo
interfacial polymerisation at a water/oil interface. Typical of such precursors are an oilsoluble
isocyanate such as those listed above and a water-soluble poly amine such as
ethylenediamine and/or diethylenetriamine :o ensure that chain extension and/or crosslinking
takes place. Cross-linking variation may be achieved by increasing the
functionality of the amine. Thus for example, cross-linking is increased if ethylenediamine
is replaced by a polyfunctional amine such as DETA (Diethylene triamine), TEPA
(Tetraethylene pentamine) and other well established cross linking amines. Isocyanate
functionality can be altered (and thus cross-linking also altered) by moving from
monomeric isocyanates such as toluene diisocyanate to PMPPI. Mixtures of isocyanates,
for example mixtures of tolylene diisocyanate and PMPPI, may also be used. Moreover,
the chemistry may be varied from aromatic isocyanates to aliphatic isocyanates such as
hexamethylenediisocyanate and isophorone diisocyanate. Further modifications can be
achieved by partially reacting the (poly) isocyanate with a polyol to produce an amount of
a polyurethane within the isocyanate chemistry to induce different properties to the wall
chemistry. For example, suitable polyols could include simple low molecular weight
aliphatic di, tri or tetraols or polymeric polyols. The polymeric polyols may be members of
any class of polymeric polyols, for example: polyether, polyTHF, polycarbonates,
polyesters and polyesteramides. One skilled in the art will be aware of many other
chemistries available for the production of a polymeric wall about an emulsion droplet. As
well as the established isocyanate/amine reaction to produce a polyurea wall chemistry,
there can be employed improvements to this technology including for example that in
which hydrolysis of the isocyanate is allowed to occur to an amine which can then further
react internally to produce the polyurea chemistry (as described for example in USP
4285720). Variation in the degree of cross linking may be achieved by altering the ratio
of monomeric isocyanate to polymeric isocyanate. As with the conventional isocyanate
technology described above, any alternative isocyanates can be employed in this
embodiment.
One skilled in the art will be aware that the various methods previously described
to produce polyurea microcaps typically leave unreacted amine (normally aromatic amine)
groups attached to the polymer matrix. In some cases it may be advantageous to convert
such amine groups to a substantially iner: functionality. Preferred are methods for the
conversion of such amine groups to urea, amide or urethane groups by post reaction of
the microcapsules in an organic solvent with a monoisocyanate, acid chloride or
chloroformate respectively.
U.S. Patent No. 6,020,066 (assigned to Bayer AG) discloses another process for
forming microcapsules having walls of polyureas and polyiminoureas, wherein the walls
are characterized in that they consist of reaction products of crosslinking agents
containing NH2 groups with isocyanates. The crosslinking agents necessary for wall
formation include di- or polyamines, diols, polyols, polyfunctional amino alcohols,
guanidine, guanidine salts, and compounds derived there from. These agents are capable
of reacting with the isocyanate groups at the phase interface in order to form the wall.
The preferred materials for the microcapsule are a polyurea, formed as described
in U.S. Pat. No. 4,285,720, or a urea-formaldehyde polymer as described in U.S. Pat.
No. 4,956,129. Polyurea is preferred because the microcapsule is formed under very
mild conditions and does not require acidic pH to promote polymerisation and so is
suitable for use when encapsulating acid-sensitive catalysts. The most preferred polymer
type for the microcapsule is polyurea as described in U.S. Pat. No. 4,285,720 based on
the PMPPI polyisocyanate either alone or in combination with other aromatic di or multi
functiopal isocyantes.
Microencapsulation techniques described above most commonly involve the
microencapsulation of an oil phase dispersed within an aqueous continuous phase, and
for such systems the catalyst is suitably capable of being suspended within the
microencapsulated oil phase or more preferably is soluble in a water-immiscible organic
solvent suitable for use as the dispersed phase in microencapsulation techniques. The
scope of the present invention is not however restricted to the use of oil-in-water
microencapsulation systems and water-soluble catalysts may be encapsulated via
interfacial microencapsulation of water-in-oil emulsion systems. Water-soluble catalysts
may also be encapsulated via interfacial microencapsulation of water-in-oil-in-water
emulsion systems.
The ligand is most preferably encapsulated along with the metal catalyst as a
component of the organic phase.
Preferably the ligand, metal catalyst, solvent and wall forming material are
dispersed as a single organic phase into the continuous aqueous phase. However, if any
of the components are incompatible then it may be advantageous to disperse all the
components separately or in combinations wherein the continuous phase conditions are
such that polymerisation is delayed until the separate organic components have mixed
through diffusion and particle coallesceneco and division. For example, the ligand can be
dissolved in an organic solvent and then dispersed into the aqueous phase either
simultaneously with the other organic components or at some stage after dispersion of
the organic solution of the metal catalyst and wall forming material.
Most preferably, the organic soluble ligand is dissolved along with the metal
catalyst and the polymerisable wall forming reactants and then all dispersed as a single
solution into the continuous aqueous phase.
The molar ratio of ligand to metal catalyst is in the range from 1/100 to 100/1 and
more preferably in the range 1/20 to 20/1 and most preferably in the range 1/10 to 10/1.
Preferred ligands are soluble in organic solvents and not sensitive to water and do
not interfere or become covalently bound into the polymer matrix.
Most preferred ligands are phosphorus based ligands of formula (1) include
P(cyclohexyl)3, PPh3, P(CH2Ph)3, P(CH2Ph)Ph2, P(p-tolyl)3, P(o-C6H4OMe)3, P(OPh)3,
P(O-p-tolyl)3, P(p-C6H4OMe)3, P(o-tolyl)3, P(m-tolyl)3, PPhCH2Ph, P(O-o-tolyl)3, PPh2(/-Pr),
PPh2Bu, PPh(cyclohexyl)2, PPh2(cyclohexyl), PPh2(CH2)4PPh2l tri(2,4-di-tertbutylphenyl)
phosphite, PPh2(CH2)3PPh2, PPh2(CH2)2PPh2
Preferably, the continuous phase is water. The amount of organic phase
dispersed into the aqueous phase may vary from 1% to about 75% by volume of the
aqueous phase present in the reactor. Preferably the amount of organic phase is about
10% to about 50% by volume.
The weight % wall forming material in the organic phase (which includes ligand,
m3tal catalyst and solvent) is in the range 5 to 95%, more preferably 10 to 70% and most
preferably 10 to 50%.
The weight % of solvent in the organic phase (which includes ligand, catalyst, wall
forming material) is in the range 5 to 95%, more preferably 15 to 90% and most
preferably 40 to 80%.
The loading level of the microencapsulated catalyst can be varied.
Microencapsulated catalysts with loadings 0.01mmol/g to 0.8mmol/g are typical,
especially where the loading is based on metal content. Loadings of 0.2mmol/g to
0.6mmol/g are preferred.
The microencapsulation of the catalyst and ligand takes place according to
techniques well known in the art. Typically the catalyst is dissolved or dispersed in an oil
phase which is emulsified into a continuous aqueous phase to form an emulsion which is
generally stabilised by a suitable surfactant system. A wide variety of surfactants suitable
for forming and stabilising such emulsions are commercially available and may be used
either as the sole surfactant or in combination. The emulsion may be formed by
conventional low or high-shear mixers or homogenisation systems, depending on particle
size requirements. A wide range of continuous mixing techniques can also be utilised.
Suitable mixers which may be employed in particular include dynamic mixers whose
mixing elements contain movable parts and static mixers which utilise mixing elements
without moving parts in the interior. Combinations of mixers (typically in series) may be
advantageous. Examples of the types of mixer which may be employed are discussed in
US patent 627132 which is herein incorporated by reference. Alternatively, emulsions
may be formed by membrane emulsification methods. Examples of membrane
emulsification methods are reviewed in Journal of Membrane Science 169 (2000) 107-
117 which is herein incorporated by reference.
Typical examples of suitable surfactants include:
a) condensates of alkyl (eg octyl, nonyl or polyaryl) phenols with ethylene oxide and
optionally propylene oxide and anionic derivatives thereof such as the
corresponding ether sulphates, ether carboxylates and phosphate esters;
block copolymers of polyethylene oxide and polypropylene oxide such as the
series of surfactants commercially available under the trademark PLURONIC
(PLURONIC is a trademark of BASF);
b) TWEEN surfactants, a series of emulsifiers comprising a range of sorbitan esters
condensed with various molar proportions of ethylene oxide;
c) condensates of C8 to C30 alkanols with from 2 to 80 molar proportions of ethylene
oxide and optionally propylene oxide; and
d) polyvinyl alcohols, including the carboxylated and sulphonated products.
Furthermore, WO 01/94001 teaches that one or more wall modifying compounds
(termed surface modifying agents) can, by virtue of reaction with the wall forming
materials, be incorporated into the microcapsule wall to create a modified microcapsule
surface with built in surfactant and/or colloid stabiliser properties. Use of such modifying
compounds may enable the organic phase wall forming material to be more readily
dispersed into the aqueous phase possibly without the use of additional colloid stabilisers
or surfactants and/or with reduced agitation. The teaching of WO01/94001 is herein
incorporated by reference. Examples of wall modifying compounds which may find
particular use in the present invention include anionic groups such as sulphonate or
carboxylate, non-ionic groups such as polyethylene oxide or cationic groups such as
quaternary ammonium salts.
In addition the aqueous phase may contain other additives which may act as aids
to the process of dispersion or the reaction process. For example, de-foamers may be
added to lesson foam build up, especially foaming due to gas evolution.
A wide variety of materials suitable for use as the oil phase will occur to one skilled
in the art. Examples include, diesel oil, isoparaffin, aromatic solvents, particularly alkyl
substituted benzenes such as xylene or propyl benzene fractions, and mixed napthalene
and alkyl napthalene fractions; mineral oils, white oil, castor oil, sunflower oil, kerosene,
dialky! amides of fatty acids, particularly the dimethyl amides of fatty acids such as
caprylic acid; chlorinated aliphatic and aromatic hydrocarbons such as 1,1,1-
trichloroethane and chlorobenzene, esters of glycol derivatives, such as the acetate of the
n-butyl, ethyl, or methyl ether of diethylene glycol, the acetate of the methyl ether of
dipropylene glycol, ketones such as isophorone and trimethylcyclohexanone
(dihydroisophorone) and the acetate products such as hexyl, or heptyl acetate. Organic
liquids conventionally preferred for use in microencapsulation processes are xylene,
diesel oil, isoparaffins and alkyl substituted benzenes, although some variation in the
solvent may be desirable to achieve sufficient solubility of the catalyst in the oil phase.
Certain catalysts may catalyse the wall-forming reaction during interfacial
polymerisation. In general it is possible to modify the microencapsulation conditions to
take account of this. Some interaction, complexing or bonding between the catalyst and
the polymer shell may be positively desirable since it may prevent agglomeration of finely
divided or colloidal catalysts.
In some instances, the catalyst being encapsulated may increase the rate of the
interfacial polymerisation reactions. In such cases it may be advantageous to cool one or
both of the organic and continuous aqueous phases such that interfacial polymerisation is
largely prevented whilst the organic phase is being dispersed. The reaction is then
initiated by warming in a controlled manner once the required organic droplet size has
been achieved. For example, in certain reactions the aqueous phase may be cooled to
less than 10°C, typically to between 5°C to 10°C, prior to addition of the oil phase and
then when the organic phase is dispersed the aqueous phase may be heated to raise the
temperature above 15°C to initiate polymerisation.
It is preferred that microencapsulation of the oil phase droplets containing the
catalyst and the ligand takes place by an interfacial polymerisation reaction as described
above under an inert atmosphere. The aqueous dispersion of microcapsules containing
the catalyst and ligand may be used to catalyse a suitable reaction without further
treatment. Preferably however the microcapsules containing the catalyst and the ligand
are removed from the aqueous phase by filtration. It is especially preferred that the
recovered microcapsules are washed with water to remove any remaining surfactant
system and with a solvent capable of extracting the organic phase contained within the
microcapsule. Relatively volatile solvents such as halogenated hydrocarbon solvents for
example chloroform are generally more readily removed by washing or under reduced
pressure than are conventional microencapsulation solvents such as alky substituted
benzenes. If the majority of the solvent is removed, the resultant microcapsule may in
effect be a substantially solvent-free polymer bead containing the catalyst efficiently
dispersed within the microcapsule polymer shell. The process of extracting the organic
phase may cause the microcapsule walls to collapse inward, although the generally
spherical shape will be retained. If desired the dry microcapsules may be screened to
remove fines, for example particles having a diameter less than about 20 microns.
In the case of the microencapsulated palladium acetate microparticles it is
preferred that the recovered water wet microcapsules are washed with copious quantities
of deionised water, followed by ethanol washes and finally hexane washes. The
microcapsules are then dried in a vac oven at 50°C for approx 4 hours to give a product
with greater than 95% non volatile content (by exhaustive drying) and preferably greater
than 98% non volatile content.
Thus according to a second aspect of the present invention there is provided a
process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the catalyst and ligand in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core and optionally
(d) recovering the microcapsules from the continuous phase.
Preferably the first phase is an organic phase and the second, continuous phase
is an aqueous phase. Suitably a protective colloid (surfactant) is used to stabilise the
emulsion.
If desired the recovered microcapsules may be washed with a suitable solvent to
extract the first phase, and in particular the organic phase solvent from the core and any
loosely bound metal catalyst or ligand. A suitable solvent, usually water, may also be
used to remove the protective colloid or surfactant.
The microcapsule wall-forming material may for example be a monomer, oligomer
or pre-polymer and the polymerisation may take place in situ by polymerisation and/or
curing of the wall-forming material at the interface. In the alternative polymerisation may
take place at the interface by the bringing together of a first wall-forming material added
through the continuous phase and a second wall-forming material in the discontinuous
phase
It has been found that the microencapsulated catalyst-ligand system obtainable by
the processes of the first and second aspects of the present invention are resistant to
both catalyst and ligand leaching and also show enhancement of activity.
According to a third aspect of the present invention there is provided a
microencapsulated catalyst-ligand system obtainable by a process comprising forming a
microcapsule shell by interfacial polymerisation in the presence of a catalyst and a ligand.
Preferred catalysts, ligands and interfacial polymerisation methods and techniques
are as stated above in connection with the first and second aspects of the present
invention.
According to a further aspect of the present invention there is provided a
microencapsulated catalyst-ligand system comprising a catalyst and a ligand
microencapsulated within a permeable polymer microcapsule shell wherein the
microcapsule shell is formed by interfacial polymerisation.
According to a further aspect of the present invention there is provided a
microencapsulated catalyst-ligand system comprising a catalyst and a ligand
microencapsulated within a permeable polymer microcapsule shell.
Preferred microencapsulated catalyst-ligand systems, catalysts, ligands and
microencapsutation methods, including interfacial polymerisation, are as stated above in
connection with the first, second and third aspects of the present invention.
Depending on the conditions of preparation and in particular the degree of
interaction between the catalyst, the ligand and the wall-forming materials, the
microencapsulated catalyst-ligand system of the present invention may be regarded at
one extreme as a 'reservoir' in which the finely divided catalyst and ligand (either as solid
or in the presence of residual solvent) is contained within an inner cavity bound by an
integral outer polymer shell or at the other extreme as a solid, amorphous polymeric bead
throughout which the finely divided catalyst and ligand is distributed. In practice the
position is likely to be between the two extremes. Regardless of the physical form of the
encapsulated catalyst-ligand of the present invention and regardless of the exact
mechanism by which access of reactants to the catalyst takes place (diffusion through a
permeable polymer shell or absorption into a porous polymeric bead), we have found that
encapsulated catalysts and ligands of the present invention permit effective access of the
reactants to the catalyst whilst presenting the catalyst and ligand in a form in which it can
be recovered and if desired re-used. Furthermore, since in the preferred embodiment of
the present invention the polymer shell/bead is formed in situ by controlled interfacial
polymerisation (as opposed to uncontrolled deposition from an organic solution of the
polymer), the microencapsulated catalyst-ligand system of the present invention may be
used in a wide range of organic solvent-based reactions.
The microcapsules of this invention are regarded as being insoluble in most
common organic solvents by virtue of the fact that they are highly crosslinked. As a
consequence, the microcapsules can be used in a wide range of organic solvent based
reactions.
The microcapsules containing the catalyst and ligand may be added to the reaction
system to be catalysed and, following completion of the reaction, may be recovered for
example by filtration. The recovered microcapsules may be returned to catalyse a further
reaction and re-cycled as desired. Alternatively, the microcapsules containing the catalyst
and ligand may be used as a stationary catalyst in a continuous reaction. For instance,
the microcapsule particles could be immobilised with a porous support matrix (e.g.
membrane). The microcapsule is permeable to the extent that catalysis may take place
either by diffusion of the reaction medium through the polymer shell walls or by absorption
of the reaction medium through the pore structure of the microcapsule.
In some circumstances, particularly where the ligand is highly reactive or may
interfere with the interfacial polymerisation process, it may be advantageous to introduce
the ligand after the polymerisation.
According to a fourth aspect of the present invention there is provided a
microencapsulated catalyst-ligand system obtainable by a process comprising forming a
microcapsule shell by interfacial polymerisation in the presence of a catalyst and treating
the microcapsule shell with a ligand.
;Optionally the microencapsulated catalyst may be isolated before subsequent
treatment with the ligand.
Treatment with the ligand may optionally be carried with or without the need to
swell the permeable polymer microcapsule shell.
Thus according to a further aspect of the present invention there is provided a
process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the catalyst in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core; and
(d) treating the microcapsules with a ligand.
Optionally the microcapsules may be recovered from the continuous phase in step
(c) before treating with the ligand in step (d).
Preferably, the ligand treated microcapsules are isolated and washed with solvent.
In some circumstances, particularly where the metal catalyst is highly reactive or
may interfere with the interfacial polymerisation process, it may be advantageous to
introduce the metal catalyst after the polymerisation.
According to a fifth aspect of the present invention there is provided a
microencapsulated catalyst-ligand system obtainable by a process comprising forming a
microcapsule shell by interfacial polymerisation in the presence of a ligand and treating
the microcapsule shell with a catalyst solution.
Optionally the microencapsulated ligand may be isolated before subsequent
treatment with the catalyst.
Treatment with the metal catalyst may optionally be carried with or without the
need to swell the permeable polymer microcapsule shell.
Thus according to a further aspect of the present invention there is provided a
process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the ligand in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core; and
_(d) treating the microcapsules with a solution of a catalyst.
Optionally the microcapsules may be recovered from the continuous phase in step
(c) before treating with the catalyst in step (d).
Preferably, the catalyst treated microcapsules are isolated and washed with
solvent.
Preferred are Catalysts wherein the ligand is first encapsulated as a component of
the organic phase and then the metal catalyst post adsorbed into the encapsulated ligand
by exposing the entrapped ligand to a solution of the metal catalyst.
More preferred are Catalysts wherein the ligand is post adsorbed into the
microencapsulated metal catalyst by exposing the entrapped metal to an organic solution
of the ligand.
Most preferred are catalysts wherein the ligand is encapsulated along with the
metal catalyst as a component of the organic phase.
The invention is illustrated by the following examples. The use of the catalysts of
the invention for catalysis of typical reactions is illustrated but the invention is not limited
to the use of the catalysts for any specific reaction. In the following Examples
GOSHENOL is polyvinyl alcohol, SOLVEJiSO 200 is just a high boiling (230- 257°C)
mixture of aromatics (mainly naphthalenes), TERGITOL XD is the polyoxypropylene
polyoxyethylene ether of butyl alcohol, REAX 100M is sodium lignosulfonate. REAX,
TERGITOL and GOSHENOL are added as colloid stabilisers and detergents.
Preparation of Comparative Catalyst Example 1 - Microencapsulated Palladium Acetate
with 40% Wall Content
Pd(OAc)2 (2.95g, 98%) was dissolved in chloroform (25.7g) and the solution stirred
for 30 minutes. To this mixture was added polymethylene polyphenylene di-isocyanate
(PMPPI) (19.11g) and the contents stirred for a further 60 minutes. The mixture was then
added to an aqueous mixture containing 40% REAX 100 M solution (3.82g), 20%
TERGITOL XD solution (0.96g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.91g) in
deionised water (80 ml) while shearing (using a FISHER 4-blade retreat curve stirrer) at
500 rpm for 8 minutes. After 8 minutes the shear rate was reduced to 250 rpm and at the
onset of polymerisation (detected by carbon dioxide evolution) 3 drops of de-foamer
(Drewplus S-4382, supplied by Ashland) were added and the suspension thus obtained
was stirred at room temperature for an additional 24 hours. The microcapsules were
filtered through a polyethylene frit (20 micron porosity) to remove any fine particles and
then washed on a filter bed according to the sequence: deionised water (5 x 100 ml),
ethanol (3 x100 ml), hexane (3 x100 ml), and then finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 4.3% Pd wt/wt, Loading: 0.4 mmol/g (60% Pd encapsulated)
Particle Size Distribution: 60-340 urn (average: 180 urn)
Preparation of Comparative Catalyst Example 2 - Microencapsulated Palladium Acetate
with 30% Wall Content
An organic phase was produced by dissolving Pd(OAc)2 (2.16g, 98%) in
chloroform (32g, 99.9%) followed by stirring for 30 minutes. To this mixture was added
polymethylene polyphenylene di-isocyanate (PMPPI) (14g) and the contents was stirred
for a further 60 minutes. The mixture was then added to an aqueous mixture containing
40% REAX 100 Ma solution (3.85g), 20% TERGITOL XDb solution (0.96g) and 25% Poly
Vinyl Alcohol (PVOH) solution (1.93 g) in deionised water (96 ml) while shearing (using a
FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. After eight minutes the
shear rate was reduced to 250 rpm and at the onset of polymerisation (as detected by
carbon dioxide evolution) 3 drops of de-foamer (Drewplus S-4382, Ashland) were added
and the suspension thus obtained was stirred at room temperature for a further 24 hours.
The microcapsules obtained were filtered though a polyethylene frit (20 micron porosity)
and then washed on a filter bed according to the sequence: deionised water (5 x 100 ml),
ethanol (3 x 100 ml), hexane (3 x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 4.1% Pd wt/wt, Loading: 0.38 mmol/g (63% Pd encapsulated)
Particle Size Distribution: 60-360 urn (average: 200 urn)
High molecular weight ethylene oxide/p'opylene oxide nonionic surfactant supplied by
The Dow Chemical Company
Preparation of Comparative Catalyst Example 3 - Microencapsulated of
Microencapsulated Palladium Acetate with 20% Wall Content
An organic phase was produced by dissolving Pd(OAc)2 (2.16g, 98%) in
chloroform (58g, 99.9%) followed by stirring for 30 minutes. To this mixture was added
polymethylene polyphenylene di-isocyanate (PMPPI) (14g) and the contents was stirred
for a further 60 minutes. The mixture was then added to an aqueous mixture containing
40% REAX 100 M solution (3.85g), 20% TERGITOL XD solution (0.96g) and 25% Poly
Vinyl Alcohol (PVOH) solution (1.93 g) in deionised water (96 ml) while shearing (using a
FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. After eight minutes the
shear rate was reduced to 250 rpm and at the onset of polymerisation (as detected by
carbon dioxide evolution) 3 drops of de-foamer (Drewplus S-4382, Ashland) were added
and the suspension thus obtained was stirred at room temperature for a further 24 hours.
The microcapsules obtained were filtered though a polyethylene frit (20 micron porosity)
and then washed on a filter bed according to the sequence: deionised water (5 x 100 ml),
ethanol (3 x 100 ml), hexane (3 x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 4.2% Pd wt/wt, Loading: 0.39 mmol/g (63% Pd encapsulated)
Particle Size Distribution: 60-395 urn (average: 211 urn)
Preparation of Comparative Catalyst Example 4 - Microencapsulation of Palladium
Acetate In a Polyurea Matrix with Reduced Crosslink Density
Pd(OAc)2 (2.95g, 98%) was dissolved in chloroform (26.4g, 99.9%) and the
solution stirred for 30 minutes. To this mixture was added polymethylene polyphenylene
di-isocyanate (PMPPI) (9.55g) and methylene bis(phenyl isocyanate) (MDI) (9.55g) and
the contents stirred for a further 60 minutes. The mixture was then added to an aqueous
mixture containing 40% REAX 100 M solution (3.88g), 20% TERGITOL XD solution
(0.97g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.94g) in deionised water (97 ml)
while shearing (using a FISHER 4-blade retreat curve stirrer) at 500 rpm for 8 minutes.
After eight minutes the shear rate was reduced to 250 rpm and at the onset of
polymerisation (as detected by carbon dioxide evolution) 3 drops of de-foamer (Drewplus
S-4382, Ashland) were added and the suspension thus obtained stirred at room
temperature for 24 hours. The microcapsules obtained were filtered though a
polyethylene frit (20 micron porosity) to remove any fine material and then washed
according to the sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3
x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 4.7% Pd wt/wt, Loading: 0.44 mmol/g (77% Pd encapsulated)
Particle Size Distribution: 60-370 urn (average: 198 um)
Preparation of Comparative Catalyst Example 5 - Microencapsulation of Palladium
Acetate In a Polyurea Matrix with Reduced Crosslink Density
Pd(OAc)2 (2.95g, 98%) was dissolved in chloroform (26.4g, 99.9%) and the
solution stirred for 30 minutes. To this mixture was added polymethylene polyphenylene
di-isocyanate (PMPPI) (9.55g) and tolylene-2,4-diisocyanate (TDI) (9.55g) and the
contents stirred for a further 60 minutes. The mixture was then added to an aqueous
mixture containing 40% REAX 100 M solution (3.88g), 20% TERGITOL XD solution
(0.97g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.94g) in deionised water (97 ml)
while shearing (using a FISHER 4-blade retreat curve stirrer) at 500 rpm for 8 minutes.
After eight minutes the shear rate was reduced to 250 rpm and at the onset of
polymerisation (as detected by carbon dioxide evolution) 3 drops of de-foamer (Drewplus
S-4382, Ashland) were added and the suspension thus obtained stirred at room
temperature for 24 hours. The microcapsules obtained were filtered though a
polyethylene frit (20 micron porosity) to remove any fine material and then washed
according to the sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3
x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 3.5% Pd wt/wt, Loading: 0.33 mmol/g (55% Pd encapsulated)
Particle Size Distribution: 40-250um (average: 124 um)
Preparation of Comparative Catalyst Example 6 - Microencapsulation of Palladium
Acetate In a Polyurea Matrix with Reduced Crosslink Density
Pd(OAc)2 (2.95g, 98%) was dissolved in chloroform (26.4g, 99.9%) and the
solution stirred for 30 minutes. To this mixture was added polymethylene polyphenylene
di-isocyanate (PMPPI) (9.55g) and 4,4-methylene bis (cyclohexyl isocyanate) (9.55g) and
the contents stirred for a further 60 minutes. The mixture was then added to an aqueous
mixture containing 40% REAX 100 M solution (3.88g), 20% TERGITOL XD solution
(0.97g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.94g) in deionised water (97 ml)
while shearing (using a FISHER 4-blade retreat curve stirrer) at 500 rpm for 8 minutes.
After eight minutes the shear rate was reduced to 250 rpm and at the onset of
polymerisation (as detected by carbon dioxide evolution) 3 drops of de-foamer (Drewplus
S-4382, Ashland) were added and the suspension thus obtained stirred at room
temperature for 24 hours. The microcapsules obtained were filtered though a
polyethylene frit (20 micron porosity) to remove any fine material and then washed
according to the sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3
x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP analysis: 4.9% Pd wt/wt, Loading: 0.46 mmol/g (80% Pd encapsulated)
Particle Size Distribution: 60-400 pm (average: 175 urn)
Preparation of Catalyst Examples 7 and 9 - Microencapsulated Pd(OAc)2 with Co-
Encapsulated
Due to air-sensitive nature of ligands, the organic phase was prepared in a glove
box under a nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (2.95g,
98%) dissolved in chloroform (25. 7g) and then stirred for 10 minutes followed by addition
of either triphenylphosphine (1.72g 99%, 1:0.5 Pd/P molar ratio) (Example 7) or tri-o-tolyl
phosphine (2g 97%, 1:0.5 Pd/P molar ratio) (Example 9) and then stirred for a further
minutes. To this mixture, polymethylene polyphenylene di-isocyanate (PMPPI) (19.11g)
was added and the contents stirred for a further 60 minutes. This organic phase mixture
was then added to an aqueous phase containing 40% REAX 100 M solution (3.95g), 20%
TERGITOL XD solution (1g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.98g) in
deionised water (83 ml) while shearing (using a FISHER 4-blade retreat-curve stirrer) at
500 rpm for 8 minutes. The reaction was maintained under inert atmosphere (N2)
throughout. After 8 minutes the shear rate was reduced to 250 rpm and few drops of defoamer
(DrewPLus S-4382) were added during the onset of polymerisation (detected by
carbon dioxide evolution). The suspension thus obtained was stirred at room temperature
for a further 24 hours. The microcapsules were then filtered though a polyethylene frit (20
micron porosity) and the capsules washed on a filter bed according to the following
sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3 x 100 ml), and
finally dried in a vacuum oven at 50°C.
Analytical Results:
Example 7:
ICP Analysis: 5.2% Pd wt/wt, Loading: 0.5 mmol/g (82% Pd encapsulated)
0.75% P wt/wt, Loading: 0.24 mmol/g (90% P encapsulated)
Particle size Distribution: 60-420um (average: 256 urn)
Example 9:
ICP Analysis: 5.1% Pd wt/wt, Loading: 0.48 mmol/g (81% Pd encapsulated)
0.75% P wt/wt, Loading: 0.24 mmol/g (89% P encapsulated)
Particle size Distribution: 60-460um (average: 311 urn)
Preparation of Catalyst Examples 8 - Microencapsulated Pd(OAc)g with Co-Encapsulated
PPrb
Due to air-sensitive nature of ligands, the organic phase was prepared in a glove
box under a nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (2.95g,
98%) dissolved in chloroform (25.7g) and then stirred for 10 minutes followed by addition
of triphenylphosphine (0.35g, 98%, 1:0.1 Pd:P) and then stirred for a further 30 minutes.
To this mixture was added polymethylene polyphenylene di-isocyanate (PMPPI) (I9.11g)
and the contents stirred for a further 60 minutes. This organic phase mixture was then
added to an aqueous phase containing 40% REAX 100 M solution (3.95g), 20%
TERGITOL XD solution (1g) and 25% Poly Vinyl Alcohol (PVOH) solution (1.98g) in
deionised water (83 ml) while shearing (using a FISHER 4-blade retreat-curve stirrer) at
500 rpm for 8 minutes. The reaction was maintained under inert atmosphere (N2)
throughout. After 8 minutes the shear rate was reduced to 250 rpm and few drops of defoamer
(DrewPLus S-4382) were added during the onset of polymerisation (detected by
carbon dioxide evolution). The suspension thus obtained was stirred at room temperature
for a further 24 hours The microcapsules were then filtered though a polyethylene frit (20
micron porosity) and the capsules washed on a filter bed according to the following
sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3 x 100 ml), and
finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 4.9% Pd wt/wt, Loading: 0.46 mmol/g (81% Pd encapsulated)
0.16% P wt/wt, Loading: 0.05 mmol/g (94% P encapsulated)
Particle size Distribution: 60-390um (average: 236 urn)
Preparation of Catalyst Example 10 - Microencapsulated Pd(OAc)? with Co-Encapsulated
1.4-bis(diphenylphosphino)butane
Due to air-sensitive nature of ligand the organic phase was prepared in a glove
box under a nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (2.95g,
98%) dissolved in chloroform (25,7g) and then stirred for 10 minutes followed by addition
of 1,4-bis(diphenylphosphino)butane (2.25g, 98%, 1:1 Pd:P) and then stirred for a further
30 minutes. To this mixture was added polymethylene polyphenylene di-isocyanate
(PMPPI) (19.11g) and the contents stirred for a further 60 minutes. This organic phase
mixture was then added to an aqueous phase containing 40% REAX 100 M solution
(3.95g), 20% TERGITOL XD solution (ig) and 25% Poly Vinyl Alcohol (PVOH) solution
(1.98g) in deionised water (83 ml) while shearing (using a FISHER 4-blade retreat-curve
stirrer) at 500 rpm for 8 minutes. The reaction was maintained under inert atmosphere
(N2) throughout. After 8 minutes the shear rate was reduced to 250 rpm and few drops of
de-foamer (DrewPLus S-4382) were added during the onset of polymerisation (detected
by carbon dioxide evolution). The suspension thus obtained was stirred at room
temperature for a further 24 hours. The microcapsules were then filtered though a
polyethylene frit (20 micron porosity) and the capsules washed on a filter bed according to
the following sequence: deionised water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3 x
100 ml.), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 5.4% Pd wt/wt, Loading: 0.51 mmol/g (82% Pd encapsulated)
1.5% P wt/wt, Loading: 0.48 mmol/g (89% P encapsulated)
Particle size Distribution: 60-495um (average: 365 pm)
Preparation of Catalyst Example 11 Microencapsulated Pd(QAc)2 with Co-Encapsulated
PPhg
Due to air-sensitive nature of the ligand, the oil phase was prepared in a glove
box. Pd(OAc)2 (3.34g, 98%) was dissolved in chloroform (46.82g) and the solution stirred
for 10 minutes. Triphenylphosphine (3.92g, 99%, 1:1 molar ratio Pd/PPh3) was then
added and the solution stirred for a further 30 minutes. To this mixture, polymethylerie
polyphenylene di-isocyanate (PMPPI) (17.59g) was added and the contents stirred for a
further 60 minutes. The mixture was then added to a cooled (4°C) aqueous mixture under
inert atmosphere (N2) containing 40% REAX 100 M solution (5.73g), 20% TERGITOL XD
solution (1.43g) and 25% Poly Vinyl Alcohol (PVOH) solution (2.87g) in deionised water
(120 ml) while shearing (using a FISHER 4-blade retrieve-curve stirrer) at 500 rpm for 8
minutes. The shear rate was then reduced to 250 rpm and after being maintained at 4°C
for 90 minutes, the temperature of the batch was gradually allowed to warm to room
temperature. At the onset of polymerisation (12°C) a few drops of de-foamer (DrewPLus
S-4382) were added. The suspension thus obtained was stirred at room temperature for
24 hours. The microcapsules were then filtered though a polyethylene frit (20 micron
porosity) and the capsules washed on a filter bed according to the sequence: deionised
water (5 x 100 ml), ethanol (3 x 100 ml), hexane (3 x 100 ml), and dried in a vacuum
oven at 50°C.
Analytical Results:
ICP Analysis: 6.4% Pd wt/wt, Loading: 0.6 mmol/g (97% Pd encapsulated)
1.9% P wt/wt, Loading: 0.6 mmol/g (98% P encapsulated)
Particle size Distribution: 60-300um (average: 133 urn)
Preparation of Catalyst Examples 1 2 - 1 7 Microencapsulated Pd(OAc)2 Catalysts with
Post Adsorbed PPha
In a 25ml round-bottom flask a sample of encapsulated palladium acetate
prepared from Comparative Examples 1-6 (1g, 0.4mmol/g Pd) was added to 10ml THF
and the mixture stirred for 30 minutes under inert (N2) atmosphere. Triphenylphosphine
ligand ,(7mg, 1:0.5 Pd:P molar ratio) was then added and the mixture allowed to stir
overnight at room temperature. The beads were then filtered and washed with THF (5ml
x 3) before being dried in a vacuum oven.
Analytical Results:
ICP results on Examples 12 to 17:
Example
12
13
14
15
16
17
Starting
Catalyst
Example
1
2
3
4
5
6
% Wall Content and
Components
40% (PMPPI)
30% (PMPPI)
20% (PMPPI)
40% (PMPPI/MDi 1/1 )
40% (PMPPI/TDI 1/1)
40% (PMPPI/Des W)
Pd level
mmol/g
(initial)
0.32 (0.4)
0.34 (0.38)
0.32 (0.39)
0.42 (0.44)
0.32 (0.33)
0.4 (0.46)
PPh3 level
mmol/g
(maximum
theoretical)
0.05 (0.2)
0.05 (0.2)
0.11 (0.2)
0.13(0.2)
0.01 (0.2)
0.11 (0.2)
Preparation of Catalyst Example 18 - Microencapsulated Triphenyl Phosphine with Post
adsorbed Pd(OAc)
Triphenylphosphine (2.70g, 99%) was dissolved in chloroform (32.7g, Aldrich 99%)
and the solution stirred for a 10 minutes. To this mixture, polymethylene polyphenylene diisocyanate
(PMPPI) (19.11g) was added and the contents stirred fora further60 minutes.
The mixture was then added to an aqueous mixture containing 40% REAX 100 M solution
(4.36g), 20% TERGOTIL XD solution (1.09g) and 25% Poly Vinyl Alcohol(PVOH) solution
(2,18g) in deionised water (91 ml) while shearing (using a FISHER 4-blade retrieve-curve
stirrer) at 500 rpm for 8 minutes. The reaction was maintained under inert atmosphere
(N2) throughout. The shear rate was then reduced to 250 rpm and few drops of defoamer
(DrewPLus S-4382) added during onset polymerisation. The dispersion thus
obtained was stirred at room temperature for 24 hours. The microcapsules were then
filtered (under N2 blanket) though a polyethylene frit (20 micron porosity) and the capsules
washed on the filter bed according to the sequence: deionised water (5 x 100 ml), ethanol
(3 x 100 ml), hexane (3 x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 1.8% P wt/wt, Loading: 0.58 mmol/g (95% PPh3 encapsulated)
Particle size Distribution: 60-320um (average: 180 urn)
Adsorption of Palladium acetate in to the Encapsulated PPh3:
Pd(OAc)2 (one molar equivalent on PPh3) was dissolved in THF (10 ml) and the
mixture stirred via magnetic stirrer for 10 minutes. To this solution the encapsulated PPh3
beads prepared above were added the mixture allowed to stir at room temperature
overnight. The beads were then filtered and washed successively with THF (10 x 10ml)
before being dried in a vacuum oven at 30°C for 3 hours.
Analytical Results:
ICP Analysis: 1.3% Pd wt/wt, Loading = 0.12 mmol/g (equates to approx 50% of Pd
adsorbed into the beads) and 0.79% P wt/wt, Loading: 0.25 mmol/g PPh3
In conclusion ICP analysis indicated that 50% of the Pd(OAc)2 was successfully loaded on
to the PPh3 beads, however approximately 50% of the initial PPh3 was lost during this
adsorption process.
Preparation of Catalyst Example 19 - Microencapsulated Pd(OAc) with Co-Encapsulated
rac-2.2'-bis(diphenylphosphino)-1.1-binaphthvl, 1:0.5 ratio Pd:P
Due to air-sensitive nature of ligand the organic phase was prepared under a
nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (1.95g, 98%)
dissolved in chloroform (43.Og) and then stirred for 10 minutes followed by addition of rac-
2,2'-bis(diphenylphosphino)-1,1-binaphthyl (1.35g, 98%, 1:0.5 Pd:P) and then stirred fora
further 20 minutes. To this mixture was added polymethylene polyphenylene diisocyanate
(PMPPI) (18.Og) and the contents stirred for a further 40 minutes. This
organic phase mixture was then added to an aqueous phase, cooled to 1°C, containing
40% REAX 100 M solution (12.86g), 20% TERGITOL XD solution (6.43g) and 25% Poly
Vinyl Alcohol (PVOH) solution (10.29g) in deionised water (108.0 ml) while shearing
(using a FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. The reaction
was maintained under inert atmosphere (N2) throughout. After 8 minutes the shear rate
was reduced to 250 rpm and few drops of de-foamer (DrewPLus S-4382) were added
during the onset of polymerisation (detected by carbon dioxide evolution). The
suspension thus obtained was stirred at 1°C for a further 1 % hours, then warmed to room
temperature (20°C) over 3 hours, maintained at room temperature for a further 16 hours
then heated at 40°C for a further 2 hours. The microcapsules were cooled to room
temperature, then filtered though a polyethylene frit (20 micron porosity) and the capsules
washed on a filter bed according to the following sequence: deionised water (5 x 100 ml),
DMF (2 x 50 ml), ethanol (2 x 50 ml), toluene (2 x 50 ml)hexane (3 x 100 ml), and finally
dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 4.2% Pd wt/wt, Loading: 0.39 mmol/g (95% Pd encapsulated)
0.51% P wt/wt, Loading: 0.165 mmol/g P (82% P encapsulated)
Particle size Distribution: 60-340um (average: 216 urn)
Preparation of Catalyst Example 20 - Microencapsulated Pd(OAc)2 with Co-Encapsulated
rac-2,2'-bis(diphenvlphosphino)-1,1-binaphthvl. 1:1 ratio Pd:P
Due to air-sensitive nature of ligand the organic phase was prepared in a glove
box under a nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (1.95g,
98%) dissolved in chloroform (43.75g) and then stirred for 10 minutes followed by addition
of rac-2,2'-bis(diphenylphosphino)-1,1-binaphthyl (2.60g, 98%, 1:1 Pd:P) and then stirred
for a further 20 minutes. To this mixture was added polymethylene polyphenylene diisocyanate
(PMPPI) (17.0g) and the contents stirred for a further 40 minutes. This organic
phase mixture was then added to an aqueous phase, cooled to 1°C, containing 40%
REAX 100 M solution (13.06g), 20% TERGITOL XD solution (6.53g) and 25% Poly Vinyl
Alcohol (PVOH) solution (10.45g) in deionised water (109.7 ml) while shearing (using a
FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. The reaction was
maintained under inert atmosphere (N2) throughout. After 8 minutes the shear rate was
reduced to 250 rpm and few drops of de-foamer (DrewPLus S-4382) were added during
the onset of polymerisation (detected by carbon dioxide evolution). The suspension thus
obtained was stirred at 1°C for a further 1 Vi hours, then warmed to room temperature
(20°C) over 3 hours and maintained at room temperature for a further 16 hours. The
microcapsules were then filtered though a polyethylene frit (20 micron porosity) and the
capsules washed on a filter bed according to the following sequence: deionised water (6 x
100 ml), ethanol (4 x 100 ml), hexane (3 x 100 ml), and finally dried in a vacuum oven at
50°C.
Analytical Results:
ICP Analysis: 4.2% Pd wt/wt, Loading: 0.39 mmol/g (97.5% Pd encapsulated)
1.2% P wt/wt, Loading: 0.39 mmol/g P (97.5% P encapsulated)
Preparation of Catalyst Example 21 - Micrconcapsulated Pd(OAc)2 with Co-Encapsulated
1J'-bis^diphenylphosphino)ferrQcene
Due to air-sensitive nature of ligand the organic phase was prepared in a glove
box under a nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (1.95g,
98%) dissolved in chloroform (43.75g) and then stirred for 10 minutes followed by addition
of 1,1'-bis(diphenylphosphino)ferrocene (2.60g, 98%, 1:1 Pd:P) and then stirred for a
further 20 minutes. To this mixture was added polymethylene polyphenylene diisocyanate
(PMPPI) (17.0g) and the contents stirred for a further 40 minutes. This
organic phase mixture was then added to an aqueous phase, cooled to 1°C, containing
40% REAX 100 M solution (13.06g), 20% TERGITOL XD solution (6.53g) and 25% Poly
Vinyl Alcohol (PVOH) solution (10.45g) in deionised water (109.7 ml) while shearing
(using a FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. The reaction was
maintained under inert atmosphere (N2) throughout. After 8 minutes the shear rate was
reduced to 250 rpm and few drops of de-foamer (DrewPLus S-4382) were added during
the onset of polymerisation (detected by carbon dioxide evolution). The suspension thus
obtained was stirred at 1°C for a further 1 % hours, then warmed to room temperature
(20°C) over 3 hours and maintained at room temperature for a further 16 hours. The
microcapsules were then filtered though a polyethylene frit (20 micron porosity) and the
capsules washed on a filter bed according t: the following sequence: deionised water (6 x
100 ml), ethanol (4 x 100 ml), hexane (3 x 100 ml), and finally dried in a vacuum oven at
Analytical Results:
ICP Analysis: 4.6% Pd wt/wt, Loading: 0.43 mmol/g (100% Pd encapsulated)
1.2% P wt/wt, Loading: 0.39 mmol/g P (97.5% P encapsulated)
Preparation of Catalvst Example 22 - Microencapsulated Pd(OAc)g with Co-Encapsulated
2-dicvclohexvlphosphinQ-1.1'-biphenvl
Due to air-sensitive nature of ligand the organic phase was prepared under a
nitrogen atmosphere. The organic phase was formed from Pd(OAc)2 (1.50g, 98%)
dissolved in chloroform (30g) and then stirred for 10 minutes followed by addition of
dicyclohexylphosphino-1,1'-biphenyl (1.91g, 98%, 1:0.82 Pd:P). To this mixture was
added polymethylene polyphenylene di-isocyanate (PMPPI) (15.0g) and the contents
stirred for a further 120 minutes. This organic phase mixture was then added to an
aqueous phase, cooled to 1°C, containing 40% REAX 100 M solution (9.70g), 20%
TERGITOL XD solution (4.85g) and 25% Poly Vinyl Alcohol (PVOH) solution (7.76g) in
deionised water (81.48 ml) while shearing (using a FISHER 4-blade retreat-curve stirrer)
at 500 rpm for 8 minutes. The reaction was maintained under inert atmosphere (N2)
throughout. After 8 minutes the shear rate was reduced to 160 rpm and few drops of defoamer
(DrewPLus S-4382) were added during the onset of polymerisation (detected by
carbon dioxide evolution). The suspension thus obtained was stirred at 1°C for a further
30 minutes, then warmed to 8°C over 2 hours and held at this temperature for 18 hours,
and then warmed to room temperature. The microcapsules were then filtered though a
polyethylene frit (20 micron porosity) and the capsules washed on a filter bed according to
the following sequence: deionised water (6 x 100 ml), DMF (2 x 100 ml), ethanol (2 x 100
ml), toluene (1 x 100 ml), hexane (2 x 100 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 3.5% Pd wt/wt, Loading: 0.33 mmol/g (92% Pd encapsulated)
0.3% P wt/wt, Loading: 0.10 mmol/g P (34% P encapsulated)
Preparation of Catalvst Example 23 - Microencapsulated Pd(QAc)2 with Co-Encapsulated
2-dicyclohexvlphqsphino-2'.4'.6'-triisopropyl-1,1 '-biphenyj
Due to air-sensitive nature of ligand the organic phase was prepared under a
nitrogen atmosphere. The organic phas=^ was formed from Pd(OAc)2 (0.94g, 98%)
dissolved in chloroform (27g) and then stirred for 10 minutes followed by addition of 2-
dicyc!ohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl (2.0g, 98%, 1:1 Pd:P). To this
mixture was added polymethylene polyphenylene di-isocyanate (PMPPI) (10.Og) and the
contents stirred for a further 120 minutes. This organic phase mixture was then added to
2-3
an aqueous phase, cooled to 1°C, containing 40% REAX 100 M solution (7.99g), 20%
TERGITOL XD solution (3.99g) and 25% Poly Vinyl Alcohol (PVOH) solution (6.39g) in
deionised water (67.10 ml) while shearing (using a FISHER 4-blade retreat-curve stirrer)
at 500 rpm for 8 minutes. The reaction was maintained under inert atmosphere (N2)
throughout. After 8 minutes the shear rate was reduced to 160 rpm and few drops of defoamer
(DrewPLus S-4382) were added during the onset of polymerisation (detected by
carbon dioxide evolution), The suspension thus obtained was stirred at 1°C for a further
30 minutes, then maintained at 5°C for 18 hours, warmed to 45°C and maintained at this
temperature for a further 2 hours. The microcapsules were then filtered though a
polyethylene frit (20 micron porosity) and the capsules washed on a filter bed according to
the following sequence: deionised water (5 x 100 ml), DMF (2 x 50 ml), ethanol (2 x 50
ml), toluene (2 x 50 ml), hexane (2 x 50 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 3.1% Pd wt/wt, Loading: 0.29 mmol/g (90.6% Pd encapsulated)
0.74% P wt/wt, Loading: 0.24 mmol/g P (75% P encapsulated)
Preparation of Catalyst Example 24 - Microencapsulated Pd(OAc)g with Co-Encapsulated
1,3-bis(2.6-diisopropylphenyl)imidazoline chloride
The organic phase was formed from Pd(OAc)2 (2.00g, 98%) dissolved in
chloroform (42.0g) and then stirred for 10 minutes followed by addition of 1,3-bis(2,6-
diisopropylphenyl)imidazoline chloride (1.90g, 1:0.5 Pd.ligand) and then stirred for a
further 40 minutes. To this mixture was added polymethylene polyphenylene diisocyanate
(PMPPI) (17.0g) and the contents stirred for a further 2 hours. This organic
phase mixture was then added to an aqueous phase, cooled to 1°C, containing 40%
REAX 100 M solution (12.58g), 20% TERGITOL XD solution (6.29g) and 25% Poly Vinyl
Alcohol (PVOH) solution (10.06g) in deionised water (105.7 ml) while shearing (using a
FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. The reaction was
maintained under inert atmosphere (N2) throughout. After 8 minutes the shear rate was
reduced to 225 rpm and few drops of de-foamer (DrewPLus S-4382) were added during
the onset of polymerisation (detected by carbon dioxide evolution). The suspension thus
obtained was stirred at 1°C for a further 1 hour, then warmed to room temperature (20°C)
over 3 hours and maintained at room temperature for a further 16 hours. The
microcapsules were then filtered though a polyethylene frit (20 micron porosity) and the
capsules washed on a filter bed according to the following sequence: deionised water (5 x
100 ml), ethanol (3 x 100 ml), hexane (2 x 100 ml), and finally dried in a vacuum oven at
50°C.
Analytical Results:
ICP Analysis: 4.6% Pd wt/wt, Loading: 0.43 mmol/g (100% Pd encapsulated)
Particle size Distribution: average: 200 urn
Preparation of Catalyst Example 25 - Microencapsulated acetato(2'-di-t-butvlphosphino-1-
1'-biphenvl-2-vl)palladiurn(ll)
The organic phase was prepared under a nitrogen atmosphere. The organic
phase was formed from acetato(2'-di-t-butylphosphino-1-1'-biphenyl-2-yl)palladium(ll)
(1.00g, 98%) dissolved in chloroform (22.3g) followed by addition of polymethylene
polyphenylene di-isocyanate (PMPPI) (10.Og) and the contents stirred for a further 90
minutes. This organic phase mixture was then added to an aqueous phase, cooled to
1°C, containing 40% REAX 100 M solution (6.66g), 20% TERGITOL XD solution (3.33g)
and 25% Poly Vinyl Alcohol (PVOH) solution (5.33g) in deionised water (55.94 ml) while
shearing (using a FISHER 4-blade retreat-curve stirrer) at 500 rpm for 8 minutes. The
reaction was maintained under inert atmosphere (N2) throughout. After 8 minutes the
shear rate was reduced to 160 rpm and few drops of de-foamer (DrewPLus S-4382) were
added during the onset of polymerisation (detected by carbon dioxide evolution). The
suspension thus obtained was stirred at 1°C for a further 30 minutes, then warmed to
25°C, held at this temperature for 18 hours, warmed to 40°C and maintained at this
temperature for a further 2 hours. The microcapsules were then filtered though a
polyethylene frit (20 micron porosity) and the capsules washed on a filter bed according to
the following sequence: deionised water (5 x 100 ml), DMF (2 x 50 ml), ethanol (2 x 50
ml), toluene (2 x 50 ml), hexane (2 x 50 ml), and finally dried in a vacuum oven at 50°C.
Analytical Results:
ICP Analysis: 2.0% Pd wt/wt, Loading: 0.19 mmol/g (95% Pd encapsulated)
0.45% P wt/wt, Loading: 0.145 mmol/g P (72.5% P encapsulated)
Catalyst Evaluations
General Procedure for Suzuki type reactions using Encapsulated Palladium Acetate
A 25 ml three-necked round-bottom flask equipped with a condenser was charged
with 4-rnethoxyphenylboronic acid (0.26g, 1.72 mmol, 1.5 eq), 4-bromofluorobenzene
(0.20g, 1.14 mmol, 1 eq), potassium carbonate (0.47g, 3.42 mmol, 3 eq) and 10 ml of IPA/H20 (20:1). To this, microencapsulated palladium acetate prepared in Comparative
Example 1 (0.08g, 3 mol%, Pd loading 0.4 mmol/g) was added. The mixture was stirred
with a magnetic follower and heated to 80°C using an oil bath. The progress of the
reaction was monitored by taking samples of reaction mixture at regular time intervals and
analysing by HPLC. The mixture was then filtered through a sintered funnel and the solid
catalystwashed with acetone and ether respectively. The filtrate was concentrated on a
rotary evaporator without further work up. ICP Analysis:revealed the reaction mixture to
have 3 ppm Pd which equates to less than 0.1% of the palladium leached from the
catalyst and the crude product to contain 20 ppm palladium.
The table below shows the level of conversion to product at timed intervals using a
quantitative HPLC method. For the catalyst Example 1 the table reveals an initial rapid
reaction, which progressively slows down over the course of reaction achieving 70%
product after 5 hours. ICP analysis showed Pd levels in reaction mixture and crude
product to be 3 ppm and 20 ppm respectively.
Time
(minutes)
0
5
10
15
20
25
30
35
40
45
95
155
Conversion (%)
0
12.5
29.6
33.3
35.6
38.1
40.8
41.2
41.8
44.6
57.7
63.4
255
285
68.6
71.1
Following the same experimental procedure reaction profiles for Comparative
Catalyst Examples 2 to 6 were produced.
The table below shows the conversion/time profiles for catalyst Examples 1, 2 and
3 with wall contents 40, 30 and 20% respectively. The catalytic activity is significantly
increased for both the 30% and 20% Pd EnCat™ against the standard 40% wall catalyst
(Example 1).
Time
(hours)
o
1
3
5
7
20
Yield (%)
Catalyst
Example 1
0
24.89
42.52
53.1
59.8
70.04
Catalyst
Example 2
0
56.47
82
86.21
90.01
95.4
Catalyst
Example 3
0
34.27
60.86
74.74
88.73
88.91
ICP Analysis on crude reaction products from catalyst Examples 1, 2 and 3 showed
20ppm, 20 ppm and 15 ppm Pd respectively.
The table below shows the conversion/time profiles for catalyst Examples 1 and 4
where Catalyst 4 has a polyurea wall with reduced crosslink density. As can be seen the
catalytic activity is significantly increased for catalyst Example 4 compared the standard
40% wall catalyst Example 1).
Time
(hours)
0
3
5
7
20
Yield (%)
Example 1
0
24.89
42.52
53.1
59.8
70.04
Example 4
0
40.69
72.41
86.42
86.64
86.85
General Procedure for Suzuki reactions using Encapsulated Palladium Acetate where
Phosphine Ligand is Post Added
To a solution of the aryl bromide (1 mmol) in isopropyl alcohol was added a
solution of the boronic acid (1.5 mmol) and potassium carbonate (3 mmol) in
isopropanol/water (20:1, 10 ml). To this mixture was added encapsulated palladium
acetate (from comparative examples 1 to 6) (0.08g, 3 mol%) followed by addition of
triphenyl phosphine at either 1/1, or 1/2 or 1/4 Pd/PPh3 molar equivalents. The reaction
was maintained under inert (N2) atmosphere and the mixture stirred at 80°C. The
progress of the reaction was monitored by taking samples of reaction mixture at regular
time intervals and analysing by HPLC. The mixture was then filtered through a sintered
funnel and the solid catalyst washed with acetone and ether respectively. The filtrate was
concentrated on a rotary evaporator without further work up. The crude product was then
analysed for Pd content by ICP.
The table below shows reaction yield / time profiles at a number of different molar
ratios of PPh3 to palladium for microencapsulated catalyst Example 1. The table reveal
that addition of PPh3 significantly increases both the rate and extent of reaction. An
induction period is observed followed by rapid reaction to achieve quantitative product
yields. The induction period is thought to relate to the time for the ligand to diffuse
through the polyurea matrix to the active metal sites.
Time
(hours)
0
0.75
2
I 3.5
I '
6
u_ 20
Yield %
Molar
Ratio
PPhs/Pd
0
0.34
0.86
31.03
82.3
92.4
Molar Ratio
PPhs/Pd
1:2
0
0.13
0.73
1.3
4.57
95.3
Molar Ratio
PPha/Pd
1:4
0
0
0.47
0.98
3.1
90.7
No PPh3
0
26.42
39.48
51.8
53.45
67.41
Comparison of Catalytic Activity of Microencapsulated Palladium Acetate with Co-
Encapsulated PPh3 (Example 7) and P(Tolvl)g (Example 9) with Comparative Catalyst
Example 1.
Catalyst Example 7 (0.06g, 3mol%) was added to a solution of 4-bromo
fluorobenzene (1 mmol), 4-methoxy phenyl boronic acid (1.5 mmol) and potassium
carbonate (3 mmol) in isopropanol/water (20:1, 10 ml). The reaction was maintained
under inert (N2) atmosphere and the mixture stirred at 80°C. The progress of the reaction
was monitored by taking samples of reaction mixture at regular time intervals and
analysing by HPLC. The mixture was then filtered through a sintered funnel and the
catalyst washed with acetone and ether respectively. The filtrate was concentrated on a
rotary evaporator without further work up and the crude product analysed for palladium
and phosphorus content by ICP: 30 ppm and 15 ppm, respectively.
The same procedure was followed for catalyst Example 9 and comparative catalyst
Example 1.
Conversion/Time data recorded for the 3 catalysts are presented in the table below:
Time
(hours)
0
1
3
5
7
20
Conversion to product (%)
Catalyst
Example 1
0
24.89
42.52
53.1
59.8
70.04
Catalyst
Example 7
0
49.98
82.16
98.08
98.14
98.42
Catalyst
Example 9
0
51.94
78.92
91.41
94.83
95.1
It can be concluded that both catalysts with co-encapsulated PAr3 ligands
demonstrate higher levels of catalytic activity compared to comparative catalyst of
Example 1.
ICP analysis of the crude reaction mixture: for catalysts Examples 1, 7 and 9 showed
palladium levels at 3ppm, 5ppm and 5ppm, respectively.
The same procedure was followed to produce conversion/time data for catalyst
Example 8 where the level of PPh3 has been reduced to 0.1/1 PPha/Pd molar equivalents:
Time
(hours)
% conversion to product
Catalyst
Example 1
0
24.89
42.52
53.1
59.8
70.04
Catalyst
Example 8
0
49.34
90.16
94.26
98.36
98.67
This catalyst still gives enhanced catalytic activity over comparative Example 1.
ICP analysis of crude product showed Pd and P levels to be <30 ppm and <18 ppm,
respectively.
The same procedure was followed to produce conversion/time profile for catalyst
Example 10 where bis(diphenylphosphino)butane was co-encapsulated. Comparison of
reaction profile for comparative Example 1 and Example 10 clearly illustrated the dramatic
improvement in activity of catalyst Example 10 with quantitative yield within 3 to 5 hours.
For catalyst Example 10 ICP analysis of crude product showed Pd and P levels to be 19
ppm and 50 ppm, respectively.
Time
(hours)
0
1
3
5
7
20
% conversion to product
Catalyst
Example 1
0
24.89
42.52
53.1
59.8
70.04
Catalyst
Example 10
0
86.61
96.17
98.05
98.59
99.2
Experiment to Assess the Influence of Storage Conditions and Ageing on Catalvst Activity
Due to presence of oxidatively labile phosphine ligands the following experiment
was carried out to determine the storage stability of the co-encapsulated catalysts of type
Examples 7 to 10.
A sample of catalyst Example 7 was stored under air for 3 months and then its
catalytic activity compared with 'fresh' catalyst in a standard Suzuki coupling reaction.
Similarly, a sample of the catalyst was subjected to accelerated ageing by warming to
52°C in an oven for 24 hours and its catalytic activity determined. Activity was assessed
by monitoring conversion/time profiles for these aged catalysts in a Suzuki reaction
according to the method above. The reaction results are presented in the table below:
Time
(hours)
Yield %
Catalyst
Example 1
0
24.89
Catalysv
Example 7
(freshly
prepared)
0
49.98
Catalyst
Example 7
(After 3 months
storage)
0
41.29
Catalyst
Example 7
(After
accelerated
ageing)
0
26.47
3
5
7
20
42.52
53.1
59.8
70.04
82.16
98.08
98.14
98.42
67.54
73
75.84
83.75
61.76
71.42
79.46
87.5
Catalyst Example 7 shows some loss of activity after storing in air for a 3 month
period, however, the catalyst still remains more active then the comparative catalyst
Example 1. Similarly accelerated ageing of Catalyst 7 at 52°C for 24 hours results in a
similar partial loss in activity.
ICP Analysis of crude products for the room temperature and 52°C aged catalyst show Pd
and P levels to be and 30 respectively.

CLAIMS
1. A microencapsulated catalyst-ligan; system comprising a catalyst and a ligand
microencapsulated within a permeable polymer microcapsule shell.
2. A microencapsulated catalyst-ligand system comprising a catalyst and a ligand
microencapsulated within a permeable polymer microcapsule shell wherein the
microcapsule shell is formed by interfacial polymerisation.
3. A microencapsulated catalyst-ligand system obtainable by a process comprising
forming a permeable microcapsule shell by interfacial polymerisation in the presence of a
catalyst and a ligand.
4. A microencapsulated catalyst-ligand system according to any one of Claims 1 to 3
wherein the permeable polymer microcapsule shell is the product of self-condensation
and/or cross-linking of etherified urea-formaldehyde resins or prepolymers in which from
about 50 to about 98% of the methylol groups have been etherified with a C4-C10 alcohol.
5. jA microencapsulated catalyst-ligand system according to any one of Claims 1 to 3
wherein the permeable polymer microcapsule shell is a polyurea microcapsule prepared
from at least one polyisocyanate and/or tolylsne diisocyanate.
6. A microencapsulated catalyst-ligand system according to Claim 5 wherein the
polyisocyanates and/or tolylene diisocyanates are selected from the group consisting of
chloro-2,4-phenylene diisocyante, m-phenylene diisocyante (and its hydrogenated
derivative), p-phenylene diisocyante (and its hydrogenated derivative), 4,4'-
methylenebis(phenyl isocyanate), 2,4-tolylene diisocyanate, tolylene diisocyanate (60%
2,4-isomer, 40% 2,6-isomer), 2,6-tolylene diisocyante, 3,3'-dimethyl-4,4'-biphenylene
diisocyante, 4,4'-methylenebis (2-methylphenyl isocyanate), 3,3'-dimethoxy-4,4'-
biphenylene diisocyanate, 2,2',5,5'-tetramethyl-4,4'-biphenylene diisocyanate, 80% 2,4-
and 20% 2,6-isomer of tolylene diisocyanate, polymethylene polyphenylisocyante
(PMPPI), 1,6-hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylene
diisocyanate and 1,5-naphthylene diisocyanate.
7. A microencapsulated catalyst-ligand system according to any one of Claims 1 to 6
wherein the catalyst is an inorganic catalyst, preferably a transition metal catalyst.
8. A microencapsulated catalyst-ligand system according to Claim 7 wherein the
catalyst is a transition metal catalyst wheroin the transition metal is platinum, palladium,
osmium, ruthenium, rhodium, iridium, rhenium, scandium, cerium, samarium, yttrium,
ytterbium, lutetium, cobalt, titanium, chromium, copper, iron, nickel, manganese, tin,
mercury, silver, gold, zinc, vanadium, tungsten and molybdenum.
9, A microencapsulated catalyst-ligand system according to Claim 8 wherein the
catalyst is a transition metal catalyst wherein the transition metal is palladium, preferably
the palladium is in the form of an organic solvent soluble form and most preferably is
palladium acetate.
10. A microencapsulated catalyst-ligand system according to any one of Claims 1 to
wherein the ligand is an organic moiety comprising one or more hetroatoms selected from
11.. A microencapsulated catalyst-ligand system according to Claim 10 wherein the
ligand is an organic ligand of formula (1):
wherein:
R1, R2 and RJ are each independently an optionally substitutsd hydrocarbyl
group, an optionally substituted hydrocarbyloxy group, or an optionally
substituted hetrocyclyl group or one or more of R1 & R2, R1 & R3, R2 & R3
optionally being linked in such a way as to form an optionally substituted
ring(s).
12. A microencapsulated catalyst-ligand system according to Claim 11 wherein the
ligand is PMe2CF3, P(OEt)3, P(Et)3l P(Bu)3, P(cyclohexyl)3, PPhEt2, PPh2Me, PPh3,
P(CH2Ph)3, P(CH2Ph)Ph2, P(p-tolyl)3, P(o-C6H4OMe)3, P(OPh)3l P(0-p-tolyl)3,
P(p-C6H4OMe)3, P(o-tolyl)3, P(m-totyl)3, PMe3, PPhMe2, PPh2Et, P(/-Pr)3> P(f-Bu)3,
PPhCH2Ph, PPh2OEt, PPh(OEt)2, P(O-o-toiyl)3, P(OMe)3, P(r)3, PPh(Pr)2, PPh2(/-Pr),
PPhBu2, PPh2Bu, P(/-Bu)3, PPh(cyciohexyl)2, PPh2(cyclohexyl), P(CH2Ph)2Et,
P(CH2Ph)Et2, P(C6F5)Ph2, P(p-C6H4F)3, P(p-C6H4CI)3, P(C6F5)2Ph, P(o-C6H4F)3,
P(o-C6H4CI)3, P(2-furanyl)3, P(2-thienyl)3> P(n-octyl)3, P(p-C6H4NO2)3,
13, A process for the preparation of a microencapsulated catalyst-ligand system which
comprises forming a microcapsule shell by interfacial polymerisation in the presence of a
catalyst and a ligand.
14. A process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the catalyst and ligand in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core and optionally
(d) recovering the microcapsules from the continuous phase.
15. A microencapsulated catalyst-ligand system obtainable by a process comprising
forming a microcapsule shell by interfacial polymerisation in the presence of a catalyst
and treating the microcapsule shell with a ligand.
16. A process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the catalyst in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core; and
(d) treating the microcapsules with a ligand.
17. A microencapsulated catalyst-ligand system obtainable by a process comprising
forming a microcapsule shell by interfacial polymerisation in the presence of a ligand and
treating the microcapsule shell with a catalyst solution.
18. A process for the preparation of a microencapsulated catalyst-ligand system which
comprises
(a) dissolving or dispersing the ligand in a first phase,
(b) dispersing the first phase in a second, continuous phase to form an
emulsion,
(c) reacting one or more microcapsule wall-forming materials at the interface
between the dispersed first phase and the continuous second phase to
form a microcapsule polymer shell encapsulating the dispersed first phase
core; and
(d) treating the microcapsules with a solution of a catalyst.
19. A process according to any one of Claims 13, 15 or 17 wherein the interfacial
polymerisation comprises self-condensation and/or cross-linking of etherified ureaformaldehyde
resins or prepolymers in which from about 50 to about 98% of the methylol
groups have been etherified with a C4-C10 alcohol.
20. A process according to any one of Claims 13, 15 or 17 wherein the interfacial
polymerisation comprises condensation of at least one polyisocyanate and/or tolylene
diisocyanate.
21. A process according to Claim 20 wherein the polyisocyanates and/or tolylene
diisocyanates are selected from the group consisting of 1-chloro-2,4-phenylene
diisocyante, m-phenylene diisocyante (and its hydrogenated derivative), p-phenylene
diisocyante (and its hydrogenated derivative), 4,4'-methylenebis(phenyl isocyanate), 2,4-
tolylene diisocyanate, tolylene diisocyanate (60% 2,4-isomer, 40% 2,6-isomer), 2,6-
tolylene diisocyante, 3,3'-dimethyl-4,4'-biphenylene diisocyante, 4,4'-methylenebis (2-
methylphenyl isocyanate), 3,3'-dimetho P(m-tolyl)3l PMe3,
PPhMe2, PPh2Et, P(/-Pr)3, P(f-Bu)3, PPhCH2Ph, PPh2OEt, PPh(OEt)2, P(O-o-tolyl)3,
P(OMe)3, P(n-Pr)3l PPh(/-Pr)2, PPh2(/-Pr), PPhBu2, PPh2Bu, P(/-Bu)3, PPh(cyclohexyl)2,
PPh2(cyclohexyl), P(CH2Ph)2Et, P(CH2Ph)Et2, P(C6F5)Ph2, P(p-C6H4F)3, P(p-C6H4CI)3,
P(C6F5)2Ph, P(o-C6H4F)3, P(o-C6H4CI)3, P(2-furanyl)3, P(2-thienyl)3, P(n-octyl)3l P(p-
C6H4N02)3,