Indian Patents. 277895:A PROCESS FOR PREPARING PARA CHLORO BENZOIC ACID FROM 4-CHLORO-2'-HYDROXY BENZOPHENONE

Title of Invention	A PROCESS FOR PREPARING PARA CHLORO BENZOIC ACID FROM 4-CHLORO-2'-HYDROXY BENZOPHENONE
Abstract	The present disclosure provides a process for oxidizing 4-chloro-2'-hydroxy benzophenone to valuable product para-chloro benzoic acid.

Full Text	FORM-2 THE PATENTS ACT, 1970 (39 of 1970) and THE PATENTS RULES, 2006 COMPLETE Specification (See Section 10; rule 13) A PROCESS FOR PREPARING PARA CHLORO BENZOIC ACID FROM 4-CHLORO-2'-HYDROXYBENZOPHENONE GHARDA KEKIHORMUSJI an Indian National of GHARDA HOUSE, 48 HILL ROAD, BANDRA (WEST), MUMBAI 400 050, MAHARASHTRA, INDIA THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS PERFORMED. This application is a divisional application for Indian Patent Application No. 3031/MUM/2010 dated 1 November 2010. Field of disclosure The present disclosure relates to a Baeyer-Villiger oxidation process of ketones. The present disclosure particularly relates to an application of Baeyer-Villiger oxidation process of 4-Chloro-2'-Hydroxybenzophenone for preparing valuable products. Background 4-chloro-4'-hydroxy benzophenone is commercially used to prepare Polyetherketone Polyetherketone, also known as polyaryletherketone (PEK), is an advanced thermoplastic resin having both ether and ketone linkages in its chains. PEK materials are semi crystalline aromatic polyesters with excellent mechanical and dielectric properties. Polyetherketone is also highly fire-resistant, has good chemical resistance, and is used for high temperature applications. Linear unsubstituted polyetherketone (PEK) is crystalline aromatic super heat resistant thermoplastic resin and find special applications in automotive, aerospace and engineering components which operate at very high temperatures. 4-Chloro-4'-hydroxybenzophenone is prepared in high yield by reacting 4-chlorobenzoyl chloride with a phenol. During the process, 4-chloro-2'-hydroxybenzophenone is formed as a by-product. For feasibility and economy of Polyetherketone process, it is necessary that the byproduct 4-chloro-2'-hydroxy benzophenone formed during the process is properly utilized. The Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. Esters can be further converted into useful alcohols and acids. Thus, Baeyer-Villiger oxidation can be applied to 4-chloro-2'-hydroxy benzophenone to convert it in to simpler and useful compounds. Therefore, there is felt a need to develop a feasible process for oxidizing 4-chloro-2'-hydroxybenzophenone in to simpler and useful compounds. Objects of the Invention The main object of the invention is to provide a process for utilization of the byproduct 4-chloro-2'-hydroxybenzophenone generated during the production of 4-chloro-4'-hydroxybenzophenone. Another object of the present invention is to provide a feasible process to oxidize 4-chloro-2'-hydroxybenzophenone in to simpler and useful compounds. Summary of the invention In accordance with the present invention, there is provided a process for preparing para-chlorobenzoic acid from 4-chloro-2'-hydroxy benzophenone, said process comprising the following steps: a) etherifying 4-chloro-2'-hydroxy benzophenone to an alkoxy benzophenone derivative of formula (II); Formula (II) wherein R represents an alkyl group, b) performing a Baeyer Villiger oxidation reaction on the alkoxy benzophenone derivative of formula (II) to obtain an ester of formula (III); Formula (III) c) hydrolyzing the ester of formula (III) at a pH in the range of 9-14, to obtain a product mixture containing salts of para-chloro benzoic acid; d) neutralizing the product mixture to obtain a biphasic system containing an organic layer and an aqueous phase containing salts of para-chloro benzoic acid; e) separating the aqueous phase from the organic phase; and f) acidifying the separated aqueous phase to obtain p-chloro benzoic acid. Typically, the etherification in step (a) is carried out in the presence of an alkylating agent selected from the group consisting of alkyl sulfonates, trialkyl phosphates , dialkyl sulfites, alkyl sulfates and alkyl halides . In a preferred embodiment of the present invention, the alkylating agent is an alkyl sulfate selected from the group consisting of dimethyl sulfate, diisopropyl sulfate and diethyl sulfate. In another preferred embodiment of the present invention, the alkylating agent is an alkyl halide selected from the group consisting of methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide , propyl and butyl halide . Typically, the alkylating agent is methyl chloride . Typically, the alkylating agent is dimethyl sulfate. Typically, the oxidation in step (b) is carried out at a temperature in the range of 10°C to 50°C. Typically, the product mixture obtained in step (c) is quenched with water to remove unreacted ester, said step of quenching carried out prior to the neutralization step (d). Typically, the hydrolysis in step (c) is carried out in an alcohol selected from the group consisting of methyl alcohol and ethyl alcohol, at a temperature in the range of 50-100°C. Typically, the aqueous phase is acidified to pH 1 to 3 to obtain para-chlorobenzoic acid. Typically, the compound of formula II is 2-Methoxy-4'-chloro benzophenone. Typically, the compound of formula III is 2'-methoxyphenyl-4-chlorobenzoate. Brief Description of the Accompanying Drawing Fig 1 illustrates a reaction scheme for preparing para-chloro benzoic acid from 4-chloro-2'-hydroxybenzophenone (o-CHBP). Detailed Description 4-Chloro-4'-hydroxybenzophenone is prepared in high yield by reacting p-chlorobenzoyl chloride with phenol. However during the process, around 1 to 10 % of the isomer 4-chloro-2'-hydroxy benzophenone is formed. The isomer is isolated by the process such as distillation and crystallization. The Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. The Baeyer-Villiger oxidation can be applied to 4-chloro-2'-hydroxy benzophenone. 4-chloro-2'-hydroxy benzophenone is subjected to Baeyer Villiger oxidation reaction to yield an ester which is then further hydrolyzed to convert it in to simpler and useful compounds. In accordance with the present invention there is provided a process for preparing para-chloro benzoic acid from4-chloro-2'-hydroxy benzophenone 4-Chlorobenzoic acid is a useful intermediate for manufacturing dyes, fungicides, pharmaceuticals and other organic chemicals. It is also used as a preservative in adhesives and paints. In accordance with the process of the present invention, 4-chloro-2' -hydroxy benzophenone (formula I) is alkylated to yield an ether 2'-alkoxy-4-chloro benzophenone of (formula II). The alkylation is carried out using an alkylating agent. Various alkylating agents can be used such as alkyl sulfonates, trialkyl phosphates, dialkyl sulfites, alkyl sulfates and alkyl halides. wherein R represents an alkyl group, In one aspect of the present invention, the alkylation is carried out using an alkyl sulfate. The alkyl sulfates usually preferred are dimethyl sulfate, diisopropyl sulfate and diethyl sulfate. In another aspect of the present invention, the alkylation is carried out using alkyl halide. The alkyl halides usually preferred are methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, propyl and butyl halide. Baeyer Villegar oxidation of 2'-alkoxy-4-chloro benzophenone yields an ester 2'-alkoxy phenyl-4-chlorobenzoate (formula III). The reaction is carried out under mild condition. During the process 4-chlorophenyl-2'-alkoxy benzoate (Formula IIIA) is also formed as byproduct. Formula III Formula IIIA The ester is then hydrolyzed to yield salts of p-chlorobenzoic acid (formula V). Formula (V) In a preferred embodiment of the present invention, 4-chloro-2'-hydroxy benzophenone is methylated to 4-chloro-2,-methoxy benzophenone. 4-chloro-2'-methoxy benzophenone so formed is then oxidized to 2'-methoxyphenyl-4-chlorobenzoate. The oxidation step is carried out in the presence of peroxy acids formed in-situ by reaction of hydrogen peroxide and per-acetic acid. The oxidation reaction is carried out at a temperature in the range of 10°C to 50°C. During oxidation process, 4-chlorophenyl-2'-methoxy benzoate is also formed. The ratio of 2'-methoxyphenyl-4-chlorobenzoate and 4-chlorophenyl-2'-methoxy benzoate is 99:1. The ester is then hydrolyzed. The hydrolysis of the ester is carried out under basic alcoholic conditions at a pH in the range of 9-14. The hydrolyzed product contains salt of p-benzoic acid. The hydrolyzed product mixture is quenched with water to remove unreacted ester if any and then neutralised to pH in the range of 8 to 6, at this pH , a biphasic system containing an organic phase and an aqueous phase is obtained. The organic phase is removed from the biphasic system and the aqueous phase is then further acidified to a pH in the range of 1-3 to crystallize out para-benzoic acid . The invention is further illustrated with the help of examples which do not limit the scope of the invention. Example 1 In a R.B. flask equipped with a stirrer was charged 200ml acetic acid. lOOgm H2S04 was then slowly added to it & the system was heated to 40°C. 1.4mole of 65% H2O2 and 1.0 mole of 2-Methoxy-4'-ChloroBenzo phenone, were added simultaneously but separately, over a period of 3 hrs maintaining the temperature of the reaction mixture at 40°C. The mixture was further stirred for a period of 6.5 hrs at 40°C. The reaction was monitored by G.C. Reaction at termination showed 91.5 % of product ester 2'-methoxyphenyl-4-chlorobenzoate, 7.3 % unreacted starting raw material 2- Methoxy 4' Chloro Benzophenone & 1.2 % of 4-chlorophenyl-2'-methoxy benzoate, ester impurity. Ratio of 2'-methoxyphenyl-4-chlorobenzoate and 4-chlorophenyl-2'-methoxy benzoate was found to be 99:1. Reaction mass was then quenched with water, the aqueous layer was further extracted with Ethylene dichloride. The Organic layer was further washed sequentially with sodium bisulfite and aqueous sodium carbonate till pH of organic layer was neutral. Organic layer was distilled to remove the solvent. 252 gm of Crude ester 2'-methoxyphenyI-4-chlorobenzoate of Purity 92%, corresponding to 92.5% yield was obtained after removal of the solvent. Crude ester was then hydrolyzed by refluxing it with methanolic NaOH for 10 hrs. After complete hydrolysis, the methanol from the hydrolyzed mixture was recovered and the concentrated mass was quenched with water, the unreacted ester was removed by extracting the mixture with EDC. The aqueous layer was then acidified to pH 8 to biphasic system containing organic phase and an aqueous phase. The organic phase is then separated and the aqueous phase is further acidified to pH 1-3 to obtain 4-chloro benzoic acid. Yield of 4-chlorobenzoic acid obtained was 88%. Example 2 In a R.B. flask equipped with a stirrer was charged 200ml acetic acid. l00gm H2S04 was then slowly added to it and the reaction system was heated to 30°C. 1.4 mole of 65% H202 & 1.0 mole 2-Methoxy-4'-Chloro Benzophenone, was added simultaneously but separately, over a period of 3 hrs maintaining temperature at 30°C. Reaction is maintained further for a total period of 15 hrs at 30°C. The reaction at termination showed 89.0 % Product ester, 9.5 % unreacted starting raw material & 1.5 % impurity ester by glc. Ratio of 2,-methoxyphenyl-4-chlorobenzoate and 4-chIorophenyl-2'-methoxy benzoate was found to be 99:1. Reaction mass after work as carried out in example -01 to yield 89% 4-chlorobenzoic acid. Example 3 In a R.B. flask equipped with a stirrer was charged 200ml acetic acid and 1.0 mole 2-Methoxy-4'-Chloro Benzophenone . 34gm H2S04 was slowly added to the mixture and the reactants mixture was heated to 40°C. 1.4mole of 65% H2O2 was then added to the mixture over a period of 6 hrs at 40°C. The reaction was carried out for a period 40hrs at 40°C, G.C analysis showed 60.0 % Product ester, 37 % unreacted starting raw material and 1.5 % ester impurity. Reaction mass after work up as carried out in example 1 yielded 57% 4-chlorobenzoic acid. While considerable emphasis has been placed herein on the specific steps of the preferred process, it will be highly appreciated that many steps can be made and that many changes can be made in the preferred steps without departing from the principles of the invention. These and other changes in the preferred steps of the invention will be apparent to those skilled in the art from the disclosures herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. I Claim: 1) A process for preparing para-chlorobenzoic acid from 4-chloro-2'-hydroxy benzophenone, said process comprising the following steps: a) etherifying 4-chloro-2'-hydroxy benzophenone to an alkoxy benzophenone derivative of formula (II); Formula (II) wherein R represents an alkyl group, Formula (III) b) performing a Baeyer Villiger oxidation reaction on the alkoxy benzophenone derivative of formula (II) to obtain an ester of formula (III); c) hydrolyzing the ester of formula (III) at a pH in the range of 9-14, to obtain a product mixture containing a salt of para-chloro benzoic acid; d) neutralizing the product mixture to obtain a biphasic system containing an organic phase and an aqueous phase containing salt of para-chlorobenzoic acid; e) separating the aqueous phase from the organic phase; and f) acidifying the aqueous phase to obtain para-chloro benzoic acid. 2) The process as claimed in claim 1, wherein the etherification in step (a) is carried out in the presence of an alkylating agent selected from the group consisting of alkyl sulfonates, trialkyl phosphates , dialkyl sulfites , alkyl sulfates and alkyl halides . 3) The process as claimed in claim 2, wherein the alkylating agent is an alkyl sulfate selected from the group consisting of dimethyl sulfate, diisopropyl sulfate and diethyl sulfate. 4) The process as claimed in claim 2, wherein the alkylating agent is an alkyl halide selected from the group consisting of methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide , propyl and butyl halide . 5) The process as claimed in claim 1, wherein the alkylating agent is methyl chloride . 6) The process as claimed in claim 1, wherein the alkylating agent is dimethyl sulfate. 7) The process as claimed in claim 1, wherein the oxidation in step (b) is carried out at a temperature in the range of I0°C to 50°C. 8) The process as claimed in claim 1, wherein the product mixture obtained in step (c) is quenched with water to remove unreacted ester, said step of quenching carried out prior to the neutralization step (d). 9) The process as claimed in claim 1, wherein the hydrolysis in step (c) is carried out in an alcohol selected from the group consisting of methyl alcohol and ethyl alcohol, at a temperature in the range of 50-100°C. 10) The process as claimed in claim 1, wherein the aqueous layer in step (f) is acidified to a pH of 1-3. 11) The process as claimed in claim 1, wherein the compound of formula II is 2-Methoxy-4'-chloro benzophenone. 12) The process as claimed in claim 1, wherein the compound of formula III is 2'-methoxyphenyl-4-chlorobenzoate.

Full Text

FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
and
THE PATENTS RULES, 2006
COMPLETE
Specification
(See Section 10; rule 13)
A PROCESS FOR PREPARING PARA CHLORO BENZOIC ACID FROM 4-CHLORO-2'-HYDROXYBENZOPHENONE
GHARDA KEKIHORMUSJI
an Indian National
of GHARDA HOUSE, 48 HILL ROAD, BANDRA (WEST), MUMBAI 400 050,
MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS PERFORMED.

This application is a divisional application for Indian Patent Application No. 3031/MUM/2010 dated 1 November 2010.
Field of disclosure
The present disclosure relates to a Baeyer-Villiger oxidation process of ketones.
The present disclosure particularly relates to an application of Baeyer-Villiger oxidation process of 4-Chloro-2'-Hydroxybenzophenone for preparing valuable products.
Background
4-chloro-4'-hydroxy benzophenone is commercially used to prepare Polyetherketone Polyetherketone, also known as polyaryletherketone (PEK), is an advanced thermoplastic resin having both ether and ketone linkages in its chains. PEK materials are semi crystalline aromatic polyesters with excellent mechanical and dielectric properties. Polyetherketone is also highly fire-resistant, has good chemical resistance, and is used for high temperature applications. Linear unsubstituted polyetherketone (PEK) is crystalline aromatic super heat resistant thermoplastic resin and find special applications in automotive, aerospace and engineering components which operate at very high temperatures.

4-Chloro-4'-hydroxybenzophenone is prepared in high yield by reacting 4-chlorobenzoyl chloride with a phenol. During the process, 4-chloro-2'-hydroxybenzophenone is formed as a by-product.
For feasibility and economy of Polyetherketone process, it is necessary that the byproduct 4-chloro-2'-hydroxy benzophenone formed during the process is properly utilized. The Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. Esters can be further converted into useful alcohols and acids. Thus, Baeyer-Villiger oxidation can be applied to 4-chloro-2'-hydroxy benzophenone to convert it in to simpler and useful compounds.
Therefore, there is felt a need to develop a feasible process for oxidizing 4-chloro-2'-hydroxybenzophenone in to simpler and useful compounds.
Objects of the Invention
The main object of the invention is to provide a process for utilization of the byproduct 4-chloro-2'-hydroxybenzophenone generated during the production of 4-chloro-4'-hydroxybenzophenone.
Another object of the present invention is to provide a feasible process to oxidize 4-chloro-2'-hydroxybenzophenone in to simpler and useful compounds.

Summary of the invention
In accordance with the present invention, there is provided a process for
preparing para-chlorobenzoic acid from 4-chloro-2'-hydroxy
benzophenone, said process comprising the following steps:
a) etherifying 4-chloro-2'-hydroxy benzophenone to an alkoxy benzophenone derivative of formula (II);

Formula (II) wherein R represents an alkyl group,
b) performing a Baeyer Villiger oxidation reaction on the alkoxy benzophenone derivative of formula (II) to obtain an ester of formula (III);

Formula (III)

c) hydrolyzing the ester of formula (III) at a pH in the range of 9-14, to obtain a product mixture containing salts of para-chloro benzoic acid;
d) neutralizing the product mixture to obtain a biphasic system containing an organic layer and an aqueous phase containing salts of para-chloro benzoic acid;
e) separating the aqueous phase from the organic phase; and
f) acidifying the separated aqueous phase to obtain p-chloro benzoic acid.
Typically, the etherification in step (a) is carried out in the presence of an alkylating agent selected from the group consisting of alkyl sulfonates, trialkyl phosphates , dialkyl sulfites, alkyl sulfates and alkyl halides .
In a preferred embodiment of the present invention, the alkylating agent is an alkyl sulfate selected from the group consisting of dimethyl sulfate, diisopropyl sulfate and diethyl sulfate.
In another preferred embodiment of the present invention, the alkylating agent is an alkyl halide selected from the group consisting of methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide , propyl and butyl halide .
Typically, the alkylating agent is methyl chloride .
Typically, the alkylating agent is dimethyl sulfate.

Typically, the oxidation in step (b) is carried out at a temperature in the range of 10°C to 50°C.
Typically, the product mixture obtained in step (c) is quenched with water to remove unreacted ester, said step of quenching carried out prior to the neutralization step (d).
Typically, the hydrolysis in step (c) is carried out in an alcohol selected from the group consisting of methyl alcohol and ethyl alcohol, at a temperature in the range of 50-100°C.
Typically, the aqueous phase is acidified to pH 1 to 3 to obtain para-chlorobenzoic acid.
Typically, the compound of formula II is 2-Methoxy-4'-chloro benzophenone.
Typically, the compound of formula III is 2'-methoxyphenyl-4-chlorobenzoate.
Brief Description of the Accompanying Drawing
Fig 1 illustrates a reaction scheme for preparing para-chloro benzoic acid from 4-chloro-2'-hydroxybenzophenone (o-CHBP).

Detailed Description
4-Chloro-4'-hydroxybenzophenone is prepared in high yield by reacting p-chlorobenzoyl chloride with phenol. However during the process, around 1 to 10 % of the isomer 4-chloro-2'-hydroxy benzophenone is formed. The isomer is isolated by the process such as distillation and crystallization.
The Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide.
The Baeyer-Villiger oxidation can be applied to 4-chloro-2'-hydroxy benzophenone. 4-chloro-2'-hydroxy benzophenone is subjected to Baeyer Villiger oxidation reaction to yield an ester which is then further hydrolyzed to convert it in to simpler and useful compounds.
In accordance with the present invention there is provided a process for preparing para-chloro benzoic acid from4-chloro-2'-hydroxy benzophenone
4-Chlorobenzoic acid is a useful intermediate for manufacturing dyes, fungicides, pharmaceuticals and other organic chemicals. It is also used as a preservative in adhesives and paints.
In accordance with the process of the present invention, 4-chloro-2' -hydroxy benzophenone (formula I) is alkylated to yield an ether 2'-alkoxy-4-chloro benzophenone of (formula II). The alkylation is carried out using an alkylating agent. Various alkylating agents can be used such as alkyl

sulfonates, trialkyl phosphates, dialkyl sulfites, alkyl sulfates and alkyl halides.

wherein R represents an alkyl group,
In one aspect of the present invention, the alkylation is carried out using an alkyl sulfate. The alkyl sulfates usually preferred are dimethyl sulfate, diisopropyl sulfate and diethyl sulfate.
In another aspect of the present invention, the alkylation is carried out using alkyl halide. The alkyl halides usually preferred are methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, propyl and butyl halide.
Baeyer Villegar oxidation of 2'-alkoxy-4-chloro benzophenone yields an ester 2'-alkoxy phenyl-4-chlorobenzoate (formula III). The reaction is carried out under mild condition. During the process 4-chlorophenyl-2'-alkoxy benzoate (Formula IIIA) is also formed as byproduct.

Formula III Formula IIIA
The ester is then hydrolyzed to yield salts of p-chlorobenzoic acid (formula V).

Formula (V)
In a preferred embodiment of the present invention, 4-chloro-2'-hydroxy benzophenone is methylated to 4-chloro-2,-methoxy benzophenone. 4-chloro-2'-methoxy benzophenone so formed is then oxidized to 2'-methoxyphenyl-4-chlorobenzoate. The oxidation step is carried out in the presence of peroxy acids formed in-situ by reaction of hydrogen peroxide and per-acetic acid. The oxidation reaction is carried out at a temperature in the range of 10°C to 50°C. During oxidation process, 4-chlorophenyl-2'-methoxy benzoate is also formed. The ratio of 2'-methoxyphenyl-4-chlorobenzoate and 4-chlorophenyl-2'-methoxy benzoate is 99:1. The ester is then hydrolyzed. The hydrolysis of the ester is carried out under basic

alcoholic conditions at a pH in the range of 9-14. The hydrolyzed product contains salt of p-benzoic acid. The hydrolyzed product mixture is quenched with water to remove unreacted ester if any and then neutralised to pH in the range of 8 to 6, at this pH , a biphasic system containing an organic phase and an aqueous phase is obtained. The organic phase is removed from the biphasic system and the aqueous phase is then further acidified to a pH in the range of 1-3 to crystallize out para-benzoic acid .
The invention is further illustrated with the help of examples which do not limit the scope of the invention.
Example 1
In a R.B. flask equipped with a stirrer was charged 200ml acetic acid. lOOgm H2S04 was then slowly added to it & the system was heated to 40°C. 1.4mole of 65% H2O2 and 1.0 mole of 2-Methoxy-4'-ChloroBenzo phenone, were added simultaneously but separately, over a period of 3 hrs maintaining the temperature of the reaction mixture at 40°C. The mixture was further stirred for a period of 6.5 hrs at 40°C. The reaction was monitored by G.C. Reaction at termination showed 91.5 % of product ester 2'-methoxyphenyl-4-chlorobenzoate, 7.3 % unreacted starting raw material 2- Methoxy 4' Chloro Benzophenone & 1.2 % of 4-chlorophenyl-2'-methoxy benzoate, ester impurity. Ratio of 2'-methoxyphenyl-4-chlorobenzoate and 4-chlorophenyl-2'-methoxy benzoate was found to be 99:1. Reaction mass was then quenched with water, the aqueous layer was further extracted with Ethylene dichloride. The Organic layer was further washed sequentially with sodium bisulfite and aqueous sodium carbonate till pH of

organic layer was neutral. Organic layer was distilled to remove the solvent. 252 gm of Crude ester 2'-methoxyphenyI-4-chlorobenzoate of Purity 92%, corresponding to 92.5% yield was obtained after removal of the solvent. Crude ester was then hydrolyzed by refluxing it with methanolic NaOH for 10 hrs. After complete hydrolysis, the methanol from the hydrolyzed mixture was recovered and the concentrated mass was quenched with water, the unreacted ester was removed by extracting the mixture with EDC. The aqueous layer was then acidified to pH 8 to biphasic system containing organic phase and an aqueous phase. The organic phase is then separated and the aqueous phase is further acidified to pH 1-3 to obtain 4-chloro benzoic acid. Yield of 4-chlorobenzoic acid obtained was 88%.
Example 2
In a R.B. flask equipped with a stirrer was charged 200ml acetic acid. l00gm H2S04 was then slowly added to it and the reaction system was heated to 30°C. 1.4 mole of 65% H202 & 1.0 mole 2-Methoxy-4'-Chloro Benzophenone, was added simultaneously but separately, over a period of 3 hrs maintaining temperature at 30°C. Reaction is maintained further for a total period of 15 hrs at 30°C. The reaction at termination showed 89.0 % Product ester, 9.5 % unreacted starting raw material & 1.5 % impurity ester by glc. Ratio of 2,-methoxyphenyl-4-chlorobenzoate and 4-chIorophenyl-2'-methoxy benzoate was found to be 99:1.
Reaction mass after work as carried out in example -01 to yield 89% 4-chlorobenzoic acid.

Example 3
In a R.B. flask equipped with a stirrer was charged 200ml acetic acid and 1.0 mole 2-Methoxy-4'-Chloro Benzophenone . 34gm H2S04 was slowly added to the mixture and the reactants mixture was heated to 40°C. 1.4mole of 65% H2O2 was then added to the mixture over a period of 6 hrs at 40°C. The reaction was carried out for a period 40hrs at 40°C, G.C analysis showed 60.0 % Product ester, 37 % unreacted starting raw material and 1.5 % ester impurity. Reaction mass after work up as carried out in example 1 yielded 57% 4-chlorobenzoic acid.
While considerable emphasis has been placed herein on the specific steps of the preferred process, it will be highly appreciated that many steps can be made and that many changes can be made in the preferred steps without departing from the principles of the invention. These and other changes in the preferred steps of the invention will be apparent to those skilled in the art from the disclosures herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

I Claim:
1) A process for preparing para-chlorobenzoic acid from 4-chloro-2'-hydroxy benzophenone, said process comprising the following steps:
a) etherifying 4-chloro-2'-hydroxy benzophenone to an alkoxy benzophenone derivative of formula (II);

Formula (II) wherein R represents an alkyl group,

Formula (III)
b) performing a Baeyer Villiger oxidation reaction on the alkoxy benzophenone derivative of formula (II) to obtain an ester of formula (III);

c) hydrolyzing the ester of formula (III) at a pH in the range of 9-14, to obtain a product mixture containing a salt of para-chloro benzoic acid;
d) neutralizing the product mixture to obtain a biphasic system containing an organic phase and an aqueous phase containing salt of para-chlorobenzoic acid;
e) separating the aqueous phase from the organic phase; and
f) acidifying the aqueous phase to obtain para-chloro benzoic acid.

2) The process as claimed in claim 1, wherein the etherification in step (a) is carried out in the presence of an alkylating agent selected from the group consisting of alkyl sulfonates, trialkyl phosphates , dialkyl sulfites , alkyl sulfates and alkyl halides .
3) The process as claimed in claim 2, wherein the alkylating agent is an alkyl sulfate selected from the group consisting of dimethyl sulfate, diisopropyl sulfate and diethyl sulfate.
4) The process as claimed in claim 2, wherein the alkylating agent is an alkyl halide selected from the group consisting of methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide , propyl and butyl halide .
5) The process as claimed in claim 1, wherein the alkylating agent is methyl chloride .
6) The process as claimed in claim 1, wherein the alkylating agent is dimethyl sulfate.

7) The process as claimed in claim 1, wherein the oxidation in step (b) is carried out at a temperature in the range of I0°C to 50°C.
8) The process as claimed in claim 1, wherein the product mixture obtained in step (c) is quenched with water to remove unreacted ester, said step of quenching carried out prior to the neutralization step (d).
9) The process as claimed in claim 1, wherein the hydrolysis in step (c) is carried out in an alcohol selected from the group consisting of methyl alcohol and ethyl alcohol, at a temperature in the range of 50-100°C.

10) The process as claimed in claim 1, wherein the aqueous layer in step (f) is acidified to a pH of 1-3.
11) The process as claimed in claim 1, wherein the compound of formula II is 2-Methoxy-4'-chloro benzophenone.
12) The process as claimed in claim 1, wherein the compound of formula III is 2'-methoxyphenyl-4-chlorobenzoate.

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Patent Number

277895

Indian Patent Application Number

2893/MUM/2011

PG Journal Number

51/2016

Publication Date

09-Dec-2016

Grant Date

05-Dec-2016

Date of Filing

17-Oct-2011

Name of Patentee

GHARDA,KEKI HORMUSJI

Applicant Address

GHARDA HOUSE,48 HILL ROAD, BANDRA(WEST), MUMBAI 400 050, MAHARASHTRA, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	GHARDA,KEKI HORMUSJI	GHARDA HOUSE,48 HILL ROAD, BANDRA(WEST), MUMBAI 400 050, MAHARASHTRA, INDIA.

PCT International Classification Number

C08L 101/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA