Title of Invention

"IMPROVED PROCESS FOR THE PREPARATION OF SATURATED CARBOXYLIC ACIDS AND THEIR ESTERS"

Abstract

An improved process for the preparation of saturated carboxylic acids and their esters by a protonic acid (or hydrogen gas) and a proton source, in an organic solvent, in the carbon monoxide atmosphere with or without phosphorous ligand, heating the mixture to a temperature ranging between 30 to 120°C, for a period ranging between 30 to 180 minutes, at a pressure ranging between 1 to 40 atm, cooling the reaction mixture to ambient temperature for flushing the reaction vessel with inert gas, removing the solvent by conventional methods as herein described, separating and isolating the saturated carboxylic acid and their esters.

Full Text

This invention relates to an improved process for the preparation of saturated carboxylic acids and their esters. Particularly this invention relates to the process for conversion of olefinicaly unsaturated compounds to corresponding carboxylic acids and esters of formula III wherein, R|, R2 RS, and R4 may independently be hydrogen, alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents, R and R5 may be H and COOR1 or vice versa wherein R' may be H in the case of acids and may be alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents in the case of esters. More particularly, it relates to the employment of an efficient catalyst, which is a compound having the formula I and contains a semilabile anionic ligand which is a chelating organic compound' containing a N donor and an O" group, for the hydrocarbonylation of olefins. In general, the olefins, which can be converted to corresponding carboxylic acids and esters, include olefins, having a general formula II. 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 styrenc by the reaction with carbonmonoxide to phenyl propanoic acids or phenyl propanoates. However it must be understood that the invention is equally applicable to the conversion of other olefins as well. The aryl and aliphatic carboxylic acids and esters have a variety of applications in industries as, anti inflammatory drugs, fine chemicals etc. The prior art describe catalyst systems for employment in processes for the preparation of esters of carboxylic acids. The best known of such catalysts is homogeneous palladium catalysts. In general, the various catalyst systems used for the hydrocarbonylation of olcfms contain a palladium source, a phosphine ligand and an hydrogen halide promoter. Hydrocarbonylation of olefms using a catalyst system comprising PdCl2 or PdCb(PPh3)2 , excess triphenylphosphine and H(l has been found to occur only at drastic conditions such as 300-700 atm of CO pressure (Bittler et. al., Angew. Chem. Internal. Edit., 7, 1968, 329). ()i ct. al. (J. Mol. Cat. A: Chem., 115, 1997, 289) have reported hydrocsterification of styrene using cationic palladium complexes and which proceeds under mild conditions (2()atm, 80°C) to give 91-94 % product yeild in four hours (TOF= 1 lh-1 ) with n: iso ratio of 60:40. Recently Scayad et. al., (Ind. Eng. Chem. Res., 37, 1998, 2180) have shown enhanced reaction rates in the hydroesterification of styrene (TOF=411h-1) using a catalyst system comprising of Pd(OAc)2, PPh3 and p-toluene sulphonic acid with an n:iso ratio of 35:64 . Eventhough a variety of palladium phosphine complexes have been used for olefin hydroesterification, metal complexes which contain N-containing ligands have never been attempted. Most of these catalyst systems cause disadvantages during the course of their employment for the preparation of carboxylic acids and esters. These disadvantages include the requirement of severe conditions, use of excess ligands and promoters. The inventors of the present invention have observed during the course of their studies that the use of a new transition metal complex of formula I which contains a semilabile anionic ligand which is a chelating organic compound containing a N donor and an O group, provides a novel catalyst for the preparation of saturated carboxylic acids and esters by hydrocarbonylation of olefinicaly unsaturated compounds. The use of such a catalyst gives good yield and selectivity and the catalyst is stable even in the absence of excess ligands and can be recycled efficiently. The object of the present invention therefore is to provide an improved process for the preparation of saturated carboxylic acids and their esters by the hydrocarbonylation of olefins. Accordingly, the present invention provides an improved process for the preparation of saturated carboxylic acids and their esters, of formula III of the drawing accompanying the specification wherein R1, R2, R3 and R4 may independently be hydrogen, alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents and R and R5 may be H and COOR' or vise versa wherein R' may be H in the case of acids and may be alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents in the case of esters, which comprises reacting an olefin of general formula III of the drawing accompanying the specification wherein R1, R2, R3 and R4 may independently be hydrogen, alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents, with a compound of formula 1 of the drawing accompanying the specification wherein R1, R2, and R3 are as described above in case of formula II and a protonic acid (or hydrogen gas) and a proton source, in an organic solvent, in the carbon monoxide atmosphere with or without phosphorous ligand, heating the mixture to a temperature ranging between 30 to 120°C, for a period ranging between 30 to 180 minutes, at a pressure ranging between 1 to 40 atm, cooling the reaction mixture to room temperature, removing the solvent by conventional methods as herein described, separating the compound of formula 1 and isolating the saturated carboxylic acid and esters of general formula III of the accompanying the specification. In one of the embodiments of the present invention the catalyst, which is a compound having formula I, is prepared as per the procedure described and claimed in our co-pending patent application No.3698/Del/98. In another embodiment the protonic acid used to may be any of the hydrohalic acids such as hydrochloric acid, hydrobromic acid and hydro iodic acid or other protonic acids such as para toluene sulphonic acid, methane sulphonic acid, triflouromethane sulphonic acid , formic acid, oxalic acid, acetic acid and trifluoro acetic acid. In yet another embodiment the phosphorous ligand if used may be any of the mono phosphines preferably phosphines such as triphenyl phosphine, tris paratolyl phosphine, tris para chlorophenyl phosphine, tris para methoxyphenyl phosphine, tricyclohexyl phosphine, tributyl phosphine and methyl diphenyl phosphine (Formula Removed) Formula I Wherein = a group VIII metal specifically palladium or platinum = substituents on the phosphine ligand such as hydrogen, alkyl, aryl, arylalkyl cycloaliphatic = groups such as aryl or alkyl sulphonato or aryl or alkyl carboxylato or formato or halides such as Cl", Br", I" = a semilabile anionic chelating ligand containing a N donar and an O" group such as 8-hydroxy quinoline, 2-hydroxy pyridine, 2-(2-hydroxy ethyl)pyridine, pyridyl-2-, piperidyl-2-, quinolyl- 2-, isoquinolyl-1- and isoquinolyl-3- carboxylates, particulaly pyridyl-2-carboxylate, piperidyl-2 carboxylate, and 8-hydroxyquinoline Kn Formula la: Formula I where, (Formula Removed) In another embodiment the proton source used may be such as water, formic acid, acetic acid and propionicacid for the prepartion of the saturated acids and any alcohol like mcthanol, ethanol, butanol or phenols for the preparation of the saturated esters. In yet another embodiment the 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 saturated 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 saturated esters. In another embodiment the concentration of catalyst may be 1 mole of catalyst for every 100 to 1000 moles of olefin, preferably 1 mole of catalyst for every 200 to 600 moles of olefin. 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 saturated esters and preferably 30-50 in the case of preparation of saturated acids. In yet another embodiment the ratio of number of moles of the mono phosphorous ligand per gram of catalyst is in a range of 1 to 100, 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. The process of 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 50 ml stirred autoclave was charged with the following rcactants Styrcnc : 0.0144 mol Catalyst having formula la6.0383 x 10-5mol p-toluene sulphonic acid: 3x10-4 mol Methanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75oC. After the temperature is attained, the autoclave was pressurised to 500 psig with carbomnonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final methyl phenyl propionate product, the pressure in the autoclave was maintained constant 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 TOF of 115h"' and 90% conversion of styrene with an n/iso ratio of 1.24. The product was then isolated by removing the solvents and remaining styrene 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 ingredients in the mixture followed by column chromatography. EXAMPLE 2 A 50 ml stirred autoclave was charged with the following reactants Styrene : 0.0144 mol Catalyst having formula la6.0383 x 10 "5 mol Mcthanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised with 50psig hydrogen gas and then to 550 psig with carbonmonoxide, stirring started and it was observed that gas absorption commenced immediately. For preparation of final methyl phenyl propionate product, the pressure in the autoclave was maintained constant using carbonmonoxide 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 TOF of 40h-1 and 95% conversion of styrene with an n/iso ratio of 1.27. The product was then isolated by removing the solvents and remaining styrene 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 followed by column chromatography. EXAMPLE 3 A 50 ml stirred autoclave was charged with the following reactants Styrene : 0.0144 mol Catalyst having formula la6.0383 x 10 -5 mol p-tolucne sulphonic acid: 3x10-4 mol Mcthannl: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbonmonoxide. Then the autoclave was pressurized to 300 psig using cthylene and stirred well in order to saturate the solvent with ethylene gas and after saturation the pressure was kept at 250 psig. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised with 500 psig of carbonmonoxide, stirring started and it was observed that gas absorption commenced immediately. For preparation of final methyl propionate product the pressure in the autoclave was maintained constant using carbonmonoxide 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 TOF of 40 h"1 and a methylpropionate selectivity of 0%. The product was then isolated by removing the solvents and remaining styrenc 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 followed by column chromatography. EXAMPLE 4 A 50 ml stirred autoclave was charged with the following reactants 4-methyl styrene: 0.0146 mol Catalyst having formula la6.0383 x 10 -5mol p-toluene sulphonic acid: 3 x 10-4 mol Methanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 60.3 h"1 and 85% conversion of 4-methyl styrene with an n/iso ratio of 1.16. The product was then isolated by removing the solvents and remaining styrene 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 followed by column chromatography. EXAMPLE 5 A 50 ml stirred autoclave was charged with the following rcactants 4-isobutyl styrenc: 0.0146 mol Catalyst having formula la6.0383 x 10 -5mol p-toluene sulphonic acid: 3 x 10-4 mol Methanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOP of 55.8 h'1 and 88% conversion of 4-isobutyl styrene with an n/iso ratio of 1.08. The product was then isolated by removing the solvents and remaining styrene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina thereby removing the catalyst and any of other ingredients in the mixture followed by column chromatography. EXAMPLE 6 A 50 ml stirred autoclave was charged with the following rcactants Styrene: 0.0146mol Catalyst having formula Ia6.0383 x 10 -5 mol p-toluene sulphonic acid: 3 x 10-4 mol Methanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 1000 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOP of 1 15h-1 and 90% conversion of styrcnc with an n/iso ratio of 0.88. The product was then isolated by removing the solvents and remaining styrene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina thereby removing the catalyst and any of other ingredients in the mixture followed by column chromatography. EXAMPLE 7 A 50 ml stirred autoclave was charged with the following reactants Final reaction mixture of example I Styrene: 0.0146mol The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 t was then cooled and the liquid phase analysed by gas chromatography. The GC analysis showed TOF of 112h-1 and 91% conversion of styrene with an n/iso ratio of 1.25. The product was then isolated by removing the solvents and remaining styrene 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 followed by column chromatography. EXAMPLE 8 A 50 ml stirred autoclave was charged with the following reactants Final reaction mixture of example 7 Styrene: 0.0146mol The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 115h-1 and 92% conversion of styrene with an n/iso ratio of 1.27. The product was then isolated by removing the solvents and remaining styrene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina thereby removing the catalyst and any of other ingredients in the mixture followed by column chromatography. EXAMPLE 9 A 50 ml stirred autoclave was charged with the following reactants Styrenc: 0.0146mol Catalyst having formula la6.0383 x 10-5mol Triphenyl phosphine: 6.0383 x 10-5mol p-toluene sulphonic acid: 3 x 10-4 mol Methanol: 23.5ml The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 125h-1 and 87% conversion of styrene with an n/iso ratio of 1.3 . The product was then isolated by removing the solvents and remaining styrene by distillation and passing a solution of the resulting mixture of products and catalyst through a glass column filled with activated alumina thereby removing the catalyst and any of other ingredients in the mixture followed by column chromatography. EXAMPLE 10 A 50 ml stirred autoclave was charged with the following reactants Final reaction mixture of example 9 Styrene: 0.0146mol The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 123h-1 and 87.4% conversion of styrene with an n/iso ratio of 1.4. EXAMPLE 11 A 50 ml stirred autoclave was charged with the following reactants Final reaction mixture of example 10 Styrene: 0.0146 mol The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75°C. After the temperature is attained, the autoclave was pressurised to 500 psig with carbonmonoxide, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 130h-1 and 90% conversion of styrene with an n/iso ratio of 1.5. EXAMPLE 12 A 50 ml stirred autoclave was charged with the following reactants Styrene: 0.0146 mol Catalyst having formula la-6.0383 x 10-5 mol Triphenyl phosphine: 6.0383 x 10-1 mol Formic acid : 0.022 mols Toluene (solvent): 0.239mols The contents of the autoclave were flushed with nitrogen and then many times with carbon monoxide. Thereafter, the contents were heated to 75oC. After the temperature is attained, the autoclave was pressurised to 500 psig with carbomnonoxkle, stirring started and it was observed that carbonmonoxide absorption commenced immediately. For preparation of final product, the pressure in the autoclave was maintained constant 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 TOF of 180h-1 and 95% conversion of styrene with an n/iso ratio of 0.85. 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 and column chromatography gave the product. Advantages of the invention 1. A novel and improved catalyst and process for the preparation of saturated carboxylic acids and their esters. 2. Provides simple and effiicient catalyst recycling 3. Avoids use of excess ligands We claim : 1. An improved process for the preparation of saturated carboxylic acids and their esters of formula III of the drawing accompanying the specification wherein R1 R2, R3 and R4 may independently be hydrogen, alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents and R and R5 may be H and COOR' or vise versa wherein R' may be H in the case of acids and may be alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents in the case of esters, which comprises reacting an olefin of general formula III of the drawing accompanying the specification wherein R1, R2, R3 and R4 may independently be hydrogen, alkyl, aryl, arylalkyl, cycloaliphatic with or without substituents, with a compound of formula 1 of the drawing accompanying the specification wherein R1, R2, and R3 are as described above in case of formula II and a protonic acid (or hydrogen gas) and a proton source, in an organic solvent, in the carbon monoxide atmosphere with or without phosphorous ligand, heating the mixture to a temperature ranging between 30 to 120°C, for a period ranging between 30 to 180 minutes, at a pressure ranging between 1 to 40 atm, cooling the reaction mixture to room temperature , removing the solvent by conventional methods as herein described, separating the compound of formula 1 and isolating the saturated carboxylic acid and esters of general formula III of the accompanying the specification. 2. An improved process as claimed in claim 1 wherein the protonic acid used is hydro halic acids selected from hydrochloric acid, hydrobromic acid and hydro iodic acid or other protonic acids selected from para toluene sulphonic acid, methane sulphonic acid, triflouromethane sulphonic acid, formic acid, oxalic acid, acetic acid and trifluoro acetic acid. 3. An improved process as claimed in claims 1-2 wherein the phosphorous ligand if used is mono phosphines preferably phosphines selected from triphenyl phosphine, tris paratolyl phosphine, tris para chlorophenyl phosphine, tris para methoxyphenyl phosphine, tricyclohexyl phosphine, tributyl phosphine and methyl diphenyl phosphine. 4. An improved process as claimed in claims 1 to 3 wherein the proton source used is water, formic acid, acetic acid and propionic acid for the preparation of the saturated acids and alcohol selected from methanol, ethanol, butanol or phenol. 5. An improved process as claimed in claims 1 to 4 wherein the solvent used is selected from aromatic hydrocarbons from benzene, toluene, xylenes, ketones selected from methyl ethyl ketone, acetone or amides N-methyl pyrrolidone or cyclic ethers tetrahydrofuran, dioxan or nitrles acetonitrile or carboxylic acids selected from formic acid, acetic acid and propionic acid for the preparation of the saturated 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 saturated esters. 6. An improved process as. claimed in claims 1 to 5 wherein the concentration of catalyst is 1 mole of catalyst for every 100 to 1000 moles of olefin, preferably 1 mole of catalyst for every 200 to 600 moles of olefin. 7. An improved process as claimed in claims 1 to 6 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 saturated esters and preferably 30-50 in the case of preparation of saturated acids. 8. An improved process as claimed in claims 1 to 7 wherein the ratio of number of moles of the mono phosphorous ligand per gram of catalyst is in a range of 1 to 100, preferably 2 to 10. 9. An improved process for the preparation of saturated carboxylic acids and their esters substantially as herein described with reference to the examples.

Documents:

54-del-1999-abstract.pdf

54-del-1999-claims.pdf

54-del-1999-correspondence-others.pdf

54-del-1999-correspondence-po.pdf

54-del-1999-description (complete).pdf

54-del-1999-drawings.pdf

54-del-1999-form-1.pdf

54-del-1999-form-19.pdf

54-del-1999-form-2.pdf

54-del-1999-form-3.pdf