Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF α, ß-UNSATURATED CARBOXYLIC ACIDS AND THEIR ESTERS

Abstract An improved process for the preparation of a, ß- unsaturated carboxylic acids and their esters An improved process for the preparation of a, ß- unsaturated carboxylic acids and their esters by reacting alkynes with a compound containing palladium in presence of a catalyst comprising of an anionic semilabile ligand, a monodentate phosphorous ligand, an acid promoter, and a proton source, in an aprotic organic solvent, in the carbonmonoxide atmosphere in a homogeneous medium at a temperature ranging between 30 to 120°C, for a period ranging between 30 to 120 minutes at atmospheric pressure, cooling the reaction mixture to 25-30°C, flushing the reaction vessel with inert gas, removing the aprotic organic solvent by conventional methods, separating the catalyst and isolating the a, P-unsaturated carboxylic acids.
Full Text This invention relates to an improved process for the preparation of α, ß-unsaturated carboxylic acids and their esters. More, particularly it relates to the improved process for conversion of acetylenically unsaturated compounds to corresponding α, ß-unsaturated carboxylic acids and their esters of formula II shown in the drawing accompanying this specification. Particularly, this invention relates to the employment of an efficient catalyst system, which contains a semilabile anionic ligand which is a chelating organic compound containing a N donor and an O" group, for the hydrocarbonylation of alkynes under normal pressure of carbon monoxide. In general, the alkynes which can be converted to corresponding α, ß-unsaturated carboxylic acids and esters, include any of the alkynes, having a general formula I. In the description here after, the invention will be described essentially in terms of the preparation of the improved catalyst and its employment for the conversion of phenyl acetylene by the reaction with carbonmonoxide to 2-phenyl propenic acids or 2-phenyl propenoates. However it must be understood that the invention is equally applicable to the conversion of other alkynes as well.
The a, (3-unsaturated carboxylic acids and esters have a variety of applications in industries as, intermediates in optically active anti inflammatory drugs, monomers for polymer synthesis, finechemicals etc.
The prior art describe improved process as catalyst systems for employment in improved processes for the preparation of of α, ß -unsaturated carboxylic acids and esters. The best known of such catalysts are homogeneous palladium
catalysts. Zagarian and Alpcr, Organometallics 1993, 12, 712-724 disclosed the palladium catalysed hydrocarboxylation of alkynes with formic acid. The catalyst system used in the improved process contained a palladium complex such as palladium acetate, mono as well as diphosphine ligands and formic acid. Even though the improved process required only mild reaction conditions the conversion rates and product selectivity were low. According to U.S.Patents No. 5,166,116 and 5,177,253 improved processes are described for the hydrocarbonylation of alkynes employing a catalyst system consisting of a group VIII metal cation, a source of organic diphosphine having atleast one of the phosphorous atoms substituted by an aromatic substituent containing an imino nitrogen atom and a source of an anion. These improved processes give high conversions to α, ß-unsaturated carboxylic acid esters and good selectivity to iso products, but need severe reaction conditions like a carbon monoxide pressure of 60 atm and use of excess ligands and acid promoters. Other main disadvantage of this catalyst system, is the complexity involved in the synthesis of the ligands used, which requires a multistep improved process which require drastic reaction conditions and are required to be handled strictly under inert atmosphere. Kushino et. al., J. Mol. Cat., 89, 1994 , 151-158 disclosed the use of a catalyst system comprising palladium bisdibenzilidine complex, triphenyl phosphine and para toluenesulphonic acid for the hydroesterification of alkynes under mild conditions. But their reaction rates and product selectivity were also poorer. Later, A.Scrivanti and U. Matteoli, Tet. lett., 36, 1995, 9015-9018 carried out the hydrocarbonylation of phenyl acetylene and
6-methoxy-2-naphthyl ethyne to corresponding a, P-unsaturated acids using the same catalyst system in the U.S.Patents No. 5,166,116 and 5,177,253. This improved process gives good rates and selectvity to the 2-substituted a,(3-unsaturated acids but use excess of ligands and promoters and again the complexities involved in the synthesis of the ligand used is an added disadvantage.
Thus, most of these catalyst systems cause disadvantages during the course of their employment for the carbonylation of alkynes. These disadvantages include the requirement of severe conditions, use of excess ligands and promoters, complexity in ligand synthesis and very low conversion and selectivity. In general, the various catalyst systems used for the hydrocarbonylation of alkynes contain a palladium source, a phosphine ligand and an acid promoter.
The inventors of the present invention have observed during the course of their studies that the use of a palladium source along with a semilabile anionic ligand which is a chelating organic compound containing a N donor and an 0"
i
group, a monodentate phosphrous ligand and a protonic acid, provides an improved catalyst for the hydrocarbonylation of acetylenically unsaturated compounds to α, ß-unsaturated carboxylic acids and esters. The use of such a catalyst gives high yield and selectivity under normal pressure of carbon monoxide.
The object of the present invention, therefore is to provide an improved process for the carbonylation of alkynes providing high selectivity to 2- substituted, α, ß- unsaturated acids and esters under normal pressure of carbon monoxide.
Accordingly, the present invention provides an improved process for the preparation of α, ß- unsaturated carboxylic acids and their esters of general formula II of the drawing accompanying this specification wherein Rl, R2 & R3 is hydrogen, alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents which comprises reacting alkynes of general formula I wherin, R1 and R2 has the meaning given above with a compound containing palladium in presence of a catalyst comprising of an anionic semilabile ligand, a monodentate phosphorous ligand, an acid promoter, and a proton source, in an aprotic organic solvent, in the carbonmonoxide atmosphere in a homogeneous medium such as herein described, at a temperature ranging between 30 to 120°C, for a period ranging between 30 to 120 minutes at atmospheric pressure, cooling the reaction mixture to 25-30°C, flushing the reaction vessel with inert gas, removing the aprotic organic solvent by conventional methods, separating the catalyst and isolating the compound of general formula II wherin, R1 and R2 is hydrogen, alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents and R3 is hydrogen in the case of acids and may be alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents in the case of esters.
In one of the embodiments of the present invention the compound containing palladium used may be palladium acetate, palladium chloride, palladium acetylacetonate and tetrakis triphenyl phosphino palladium.
In another embodiment the anionic semilabile chelating ligand used may be organic compound containing a N donor and an O" group, exemplified by pyridine carboxylic acids, piperidine carboxylic acids , 8-hydroxy quinoline or their derivatives .
In yet another embodiment the phosporous ligand used may be any of the mono phosphines or phosphites or a member of their family. Preferably phosphines such as triphenyl phosphine, tris paratolyl phosphine , tris para chlorophenyl phosphine, tris para methoxyphenyl phosphine, tricyclohexyl phosphine, tributyl phosphine, triphenyl phosphite, tributyl phosphite.
In still another embodiment the acid promotor used may be any protonic acids of the kind, para toluene sulphonic acid, methane sulphonic acid, triflouro methane sulphonic acid, acetic acid, formic acid, oxalic acid and trifouro acetic acid.
In another embodiment the proton source used may be such as water, formic acid, acetic acid and propionicacid for the prepartion of the α, ß- unsaturated acids and any alcohol like methanol, ethanol, butanol or phenols for the preparation of the α, ß- unsaturated esters.
In yet another embodiment the aprotic organic solvent used may be any of the aprotic solvents such as aromatic hydrocarbons like, benzene, toluene, xylenes, ketones like methyl ethyl ketone, acetone or amides like N-methyl pyrrolidone or cyclic ethers such as tetrahydrofuran, dioxan or nitrles such as acetonitrile or carboxylic acids such as formic acid, acetic acid and propionic acid for the prepartion of the α, ß_ unsaturated acids and the alcohol used as the proton source itself or aromatic hydrocarbons like, benzene, toluene, xylenes, or ketones like methyl ethyl ketone, acetone or amides like N-methyl pyrrolidone or cyclic ethers such as tetrahydrofuran and dioxan for the preparation of the α, ß- unsaturated esters.
In another embodiment the concentration of palladium compound in the catalyst system may be 1 mole of palladium compound for every 100 to 1000 moles of alkyne, preferably 1 mole of palladium compound for every 200 to 600 moles of alkyne.
In another embodiment the number of moles of the anionic semilabile ligand per gram atom of palladium in the catalyst system may be in the range of 1 to 100 moles preferably 2 to 10.
In still another embodiment the number of moles of acid promoter per gram atom of palladium in the catalyst system may be in the range of 1 to 100
moles preferably, 2 to 10 in the case of preparation of α, ß- unsaturated esters and preferably 30-50 in the case of preparation of α, ß- unsaturated acids.
In yet another embodiment the ratio of number of moles of the mono phosphorous ligand per gram of palladium in the catalyst system may be in a range
In another embodiment the ratio of number of moles of proton source per mole of the alkyne may be in a range 1 to 50 moles, preferably 2 to 10.
In a feature of the invention the reaction can be conveniently carried out in a stirred reactor with the improved catalyst employed in homogeneous phase with a suitable solvent in presence of carbon monoxide at atmospheric pressure.
The improved process for the prepartation of α, ß- unsaturated acids and their esters, the present invention is described herein below with examples which are illustrative only and should not be construed to limit the scope of the present invention in any manner.
EXAMPLE 1 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols
Pd(OAc)2: 1.94 x 10 mols
2-Picolinic acid: 3.88 x 10 mols
Triphenylphosphine: 7.76 x 10-4 mols
Para toluene sulphonic acid: 3.88 x 10-4mols
Butanol: 0.162mols
Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, triphenyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography (GC). The GC analysis
showed initial TOF (turn over frequency) of 600h-1 and 50% conversion of phenyl acetylene with 98% selectivity to butyl 2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 2 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene: 0.039mols Pd(OAc)2: l.94 x l0-4 mols 2-Pipecolinic acid: 3.88 x l0-4 mols Triphenylphosphine: 7.76 x 10-4 mols Para toluene sulphonic acid: 3.88 x 10 mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously
when the contents of the reactor palladium acetate, 2-pipecolinic acid, para toluene acetic acid, triphenyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 600h-1 and 50% conversion of phenyl acetylene with 98% selectivity to butyl 2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 3 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: 1.94 x 10~4mols
8-hydroxyquinoline: 3.88 x 10-4 mols Triphenylphosphine: 7.76 x 10-4mols Para toluene sulphonic acid: 3.88 x 10-4 mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 8-hydroxy quinoline para toluene acetic acid, triphenyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 300h-1 and 25% conversion of phenyl acetylene with 85%
selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 4 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: 1.94xl0-4mols 2-Picolinic acid: 3.88 x 10-4 mols Tris para chlorophenylphosphine: 7.76 x 10-4 mols Para toluene sulphonic acid: 3.88 x 10 mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para
toluene acetic acid, tris para chlorophenyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 700h-1 and 98% conversion of phenyl acetylene with 98% selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 5 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: 1.94 x 10-4mols 2-Picolinic acid: 3.88 x 10-4 mols
Tris paratolyl phosphine: 7.76 x 10-4mols Para toluene sulphonic acid: 3.88 x 10-4mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, tris paratolyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 650h-1 and 60% conversion of phenyl acetylene with 98% selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 6 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: l.94 x 10-4 mols 2-Picolinic acid: 3.88 x 10-4 mols Tributyl phosphine: 7.76 x 10-4mols Para toluene sulphonic acid: 3.88 x 10 mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, tributyl phosphine, phenylacetylene and butanol were came
in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography The GC analysis showed initial TOF of 130h-1 and 10% conversion of phenyl acetylene with 94% selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 7 A 300 ml stirred autoclave was .charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: 1.94 x 10-4mols 2-Picolinic acid: 3.88 x 10 mols Tri cyclohexyl phosphine: 7.76 x 10-4 mols
Para toluene sulphonic acid: 3.88 x 10-4mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, tricyclohexyl phosphine, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 20h-1 and 3% conversion of phenyl acetylene with 92% selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 8 A 300 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.039mols Pd(OAc)2: l.94 x 10-4 mols 2-Picolinic acid: 3.88 x 10-4mols Triphenylphosphite: 7.76 x 10-4mols Para toluene sulphonic acid: 3.88 x 10 mols Butanol: 0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, triphenyl phosphite, phenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide
in the gaseous phase.
For preparation of final butyl-2-phenylpropenoate product, the pressure in the autoclave was maintained constant (the total pressure was around 15 psig at 100°C when the reaction started) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed
initial TOF of 120h-1 and 10% conversion of phenyl acetylene with 94%
selectivity to butyl-2-phenyl propenoate.
The product was then isolated by removing the solvents and remaining phenylacetylene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture.
EXAMPLE 9 A 300 ml stirred autoclave was charged with the following reactants 1,2-diphenyl acetylene : 0.039mols Pd(OAc)2: l.94 x10-4mols 2-Picolinic acid: 3.88 x 10 mols Triphenylphosphine: 7.76 x 10-4 mols Para toluene sulphonic acid: 3.88 x 10" mols
Butanol:0.162mols Toluene (solvent): 0.652mols
The contents of the autoclave were flushed with nitrogen and then twice with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene acetic acid, triphenyl phosphine, 1,2-diphenylacetylene and butanol were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final butyl-2,3-diphenylpropenoate product, the pressure in the autoclave was maintained constant at 15 psig (total pressure) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 200h-1 and 20% conversion of 1,2-diphenylacetylene with 100% selectivity to butyl- 2,3-diphenyl propenoate.
The product was then isolated by removing the solvents by distillation and
passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina therby removing the catalyst and any of other ingradients in the mixture. The substrate remained was separated column chromatography.
EXAMPLE 10 A 50 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.0147mols Pd(OAc)2: 7.2767 x 10-5 mols 2-Picolinic acid: 1.433 x 10-4mols Triphenylphosphine: 2.9 x 10-4mols Formic acid : 0.022 mols Toluene (solvent): 0.239mols
The contents of the autoclave were flushed with nitrogen and then twice with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, formic acid triphenyl phosphine and phenylacetylene were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final 2-phenylpropenoic acid product, the pressure in the autoclave was maintained constant at 15 psig (total pressure) and the progress, of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 500 h-1 and 99% conversion of phenylacetylene with 96 % selectivity to 2-phenyl propenoic acid.
The final reaction mixture was washed many times with water to remove formic acid and then extracted with 10% NaOH solution to get the sodium salt of 2-phenylpropenoic acid in the NaOH layer. The NaOH layer was separated and acidified with 10% HC1 and extracted by diethyl ether which on subsequent evaporation gave the product as white crystals.
EXAMPLE 11 A 50 ml stirred autoclave was charged with the following reactants Phenyl acetylene : 0.0147mols Pd(OAc)2: 7.2767 x 10-5 mols 2-Picolinic acid: 1.433 x 10-4mols Triphenylphosphine: 2.9 x 10 mols p-toluene sulphonic acid : 0.0157 mols Water: 0.027mols Acetone (solvent): 0.239mols
The contents of the autoclave were flushed with nitrogen and then twice with carbon monoxide. Thereafter, the contents were heated to 100°C. After the temperature is attained, stirring started and it was observed that carbonmonoxide absorption commenced immediately. This confirmed that the active catalyst for the carbonylation reaction was formed insitu instantaneously when the contents of the reactor palladium acetate, 2-picolinic acid, para toluene sulphonic acid triphenyl phosphine and phenylacetylene were came in contact under reaction conditions in the presence of carbonmonoxide in the gaseous phase.
For preparation of final 2-phenylpropenoic acid product, the pressure in the autoclave was maintained constant at 15 psig (total pressure) and the progress of the reaction was monitored by observing the pressure drop and by liquid sampling. The reaction was continued until the pressure drop was too low. The reactor was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed initial TOF of 450 h-1 and 99% conversion of phenylacetylene with 98 % selectivity to. 2-phenyl propenoic acid.
The final reaction mixture was washed many times with water to remove formic acid and then extracted with 10% NaOH solution to get the sodium salt of 2-phenylpropenoic acid in the NaOH layer. The NaOH layer was separated and acidified with 10% HC1 and extracted by diethyl ether which on
subsequent evaporation gave the product as white crystals.
Advantages of the invention
1. A novel and improved catalyst system for the preparation of α, ß-unsaturated carboxylic acids and their esters.
2. Provides high reaction rates and high selectivity to the 2-substituted α, ß-unsaturated carboxylic acids and their esters under ambient pressure of carbonmonoxide.
3. Use of simple ligands which are easily available in the market and are cheap.
4. Avoids use of excess ligands and promoters.





We Claim:-
1. An improved process for the preparation of α, ß- unsaturated carboxylic acids and their esters of general formula II of the drawing accompanying this specification wherein Rl, R2 & R3 is hydrogen, alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents which comprises reacting alkynes of general formula I wherin, R1 and R2 has the meaning given above with a compound containing palladium in presence of a catalyst comprising of an anionic semilabile ligand, a monodentate phosphorous ligand, an acid promoter, and a proton source, in an aprotic organic solvent, in the carbonmonoxide atmosphere in a homogeneous medium such as herein described, at a temperature ranging between 30 to 120°C, for a period ranging between 30 to 120 minutes at atmospheric pressure, cooling the reaction mixture to 25-30°C, flushing the reaction vessel with inert gas, removing the aprotic organic solvent by conventional methods, separating the catalyst and isolating the compound of general formula II wherin, R1 and R2 is hydrogen, alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents and R3 is hydrogen in the case of acids and may be alkyl, aryl, arylalkyl, cyclaliphatic with or without substituents in the case of esters.
2. An improved process as claimed in claim 1 wherein, the compound containing palladium used is selected from palladium acetate, palladium

chloride, palladium acetylacetonate, tetrakis triphenyl phosphino palladium.
3. An improved process as claimed in claims 1 and 2, wherein the anionic semilabile chelating ligand used is an organic compound containing a N donor and an O" group selected from pyridine carboxylic acids, piperidine carboxylic acids, 8-hydroxy quinoline or their derivatives.
4. An improved process as claimed in claims lto 3 wherein, the phosporous ligand used is selected from mono phosphines or phosphites or a member of their family. Preferably phosphines such as triphenyl phosphine, tris paratolyl phosphine, tris para chlorophenyl phosphine, tris paramethoxyphenyl phosphine, tricyclohexyl phosphine, tributyl phosphine, triphenyl phosphite, tributyl phosphite.
5. An improved process as claimed in claims 1 to 4 wherein, the acid promotor used is selected from para toluene sulphonic acid, methane sulphonic acid, triflouro methane sulphonic acid, acetic acid, formic acid, oxalic acid , trifouro acetic acid.
6. An improved process as claimed in claims 1 to 5 wherein, the proton source used is selected from water, formic acid, acetic acid and propionicacid for the prepartion of the a, (3- unsaturated acids and any alcohol like methanol, ethanol, butanol or phenols for the preparation of the α, ß- unsaturated esters.
7. An improved process as claimed in claims 1 to 6 wherein, the aprotic solvents is selected from benzene, toluene, xylenes, ketones selected from methyl ethyl ketone, acetone or amides selected from N-methyl pyrrolidone or cyclic ethers selected from tetrahydrofuran, dioxan or nitrles selected from acetonitrile or carboxylic acids selected from formic acid, acetic acid and propionic acid for the prepartion of the a, (3-unsaturated acids and the alcohol used as the proton source itself or aromatic hydrocarbons selected from benzene, toluene, xylenes, or ketones selected from methyl ethyl ketone, acetone or amides selected from N-methyl pyrrolidone or cyclic ethers selected from tetrahydrofuran and dioxan for the preparation of the a, (3- unsaturated esters is used.
8. An improved process as claimed in claims 1 to 7, wherein the concentration of palladium compound is 1 mole of palladium compound for every 100 to 1000 moles of alkyne, preferably 1 mole of palladium compound for every 200 to 600 moles of alkyne.
9. An improved process as claimed in claim 1 to 8, wherein the number of moles of the anionic semilabile ligand per gram atom of palladium in thecatalyst system is in the range of 1 to 100 moles preferably 2 to 10
10. An improved process as claimed in claims 1 to 9, wherein the number of moles of acid promoter per gram atom of palladium in the catalyst system is in the range of 1 to 100 moles preferably 2 to 10 in the case of
preparation of α, ß- unsaturated esters and preferably 30-50 in the case of preparation of α, ß- unsaturated acids.
11. An improved process as claimed in claims 1 to 10, wherein the ratio of number of moles of the mono phosphorous ligand per gram of palladium in the catalyst system is in a range of 1 to 100 moles, preferably 2 to 10.
12. An improved process as claimed in claims 1 to 11, wherein the ratio of number of moles of proton source per mole of the alkyne is in a range 1 to 50 moles, preferably 2 to 5.
13. An improved process for the preparation of α, ß-unsaturated carboxylic acids and their esters of general formula II as defined in claim 1 as described herein before with reference to examples.

Documents:

3693-del-1998-abstract.pdf

3693-del-1998-claims.pdf

3693-del-1998-complete specification (granted).pdf

3693-del-1998-correspondence-others.pdf

3693-del-1998-correspondence-po.pdf

3693-del-1998-description (complete).pdf

3693-del-1998-drawings.pdf

3693-del-1998-form-1.pdf

3693-del-1998-form-19.pdf

3693-del-1998-form-2.pdf

3693-del-1998-form-3.pdf

3693-del-1998-petition-138.pdf


Patent Number 246187
Indian Patent Application Number 3693/DEL/1998
PG Journal Number 08/2011
Publication Date 25-Feb-2011
Grant Date 18-Feb-2011
Date of Filing 09-Dec-1998
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 RAGHUNATH VITTHAL CHAUDHARI NATIONAL CHEMICAL LABORATORY, PUNE, 411008, MAHARASHTRA INDIA
2 JAYASREE P. SUNIL PURUSHOTHAM GUPTE NATIONAL CHEMICAL LABORATORY, PUNE, 411008, MAHARASHTRA INDIA
PCT International Classification Number C07C 57/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA