Title of Invention

PROCESS FOR SYNTHESIS OF ALKYL ALKOXY BENZOATES

Abstract

The invention relates to a process for synthesis of alkyl alkoxy benzoates having the general formula where R, R1 is a C1-10 alkyl, R and R1 being different from one another, in high yields, the process comprising reacting a phenol having the formula with an alkylating agent in the presence of a base, molar ratio of the phenol, the alkylating agent and the base being 1.0: 1.0-1.4: 1.0-1.5, the process being carried out at a temperature in the range of 70-90°C in an alcohol solvent having the formula R1OH where R1 is the same as the R1 of the benzoate group.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) As amended by the Patents (Amendment) Act, 2005 & The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2005 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION O-alkylation of phenols containing a benzoate group in high yields APPLICANTS Name : Reliance Industries Limited Nationality an Indian company Address : 5th Floor, Maker Chamber IV, Nariman Point,Mumbai 400 021, Maharashtra, India INVENTORS Names : Gupta, Virendrakumar; Ganeshpure, Pralhad Ambadas; Patil, Harshad Ramdas; Naik, Dhananjay Ghelabhai Nationality : all Indian Nationals Address : all of Reliance Industries Limited, 5 Floor, Maker Chamber IV, Nariman Point,Mumbai 400 021, Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed : Field of invention The invention relates to a process for synthesis of alkyl alkoxy benzoates, in high yields. Background of invention Alkyl alkoxy benzoates find applications as starting materials for the synthesis of a large variety of organic compounds. They are also widely used as anesthetics and as selectivity control agents in Ziegler-Natta type polymerization catalysts. Alkyl alkoxy benzoates are usually prepared by O-alkylation of the corresponding phenols carrying benzoate group. The O-aikylation of phenols carrying a benzoate group is not desirable in aqueous medium due to the likelihood of hydrolysis of the benzoate group. EP 834510 describes a process for O-alkylating, in DMF solvent, a phenol containing benzoate group in the ring by reacting the phenol with two equivalents of alkylating agent in the presence of anhydrous potassium carbonate at 100°C for 24 hours. However, even after such a long reaction time, the yield of the alkylated phenol obtained from the reaction is low. Apart from this, the isolation of the alkylated product from DMF is difficult. Also, recovery of the solvent DMF used in the process is tedious and expensive. It is desirable to have a process for synthesis of alkyl alkoxy benzoates without the above mentioned disadvantages. Accordingly, the invention provides a process for synthesis of alkyl alkoxy benzoates in high yields by carrying out alkylation of an alcohol substituted benzoate, in the presence of a base in an alcohol. The alcohol used in the process is so selected as to have an alkyl part same as the alkyl part of the benzoate group. the process is so selected as to have an alkyl part same as the alkyl part of the benzoate group. In particular, the invention provides a process for synthesis of alkyl alkoxy benzoates having the general formula OR COOR' where R, R is a C1-10 alkyl, R and R being different from one another, in high yields of 80 - 100%, the process comprising reacting a phenol having the formula OH COOR' with an alkylating agent in the presence of a base, molar ratio of the phenol, the alkylating agent and the base being 1.0: 1.0-1.4: 1.0-1.5, wherein the process is carried out at a temperature in the range of 70-90°C for a period of 8 - 10 hrs, in an alcohol solvent having the formula R OH where R is the same as the R of the benzoate group. The process of the invention is applicable to a broad range of phenols having benzoate group present as the ring substituent. In addition to the benzoate group, the phenol alkylated using the process of the invention can have other substituents provided that such substituents do not interfere with the alkylation of the phenolic -OH group. Suitable other substituents include, but are not limited to, alkyl, carboxylic acids, aldehydes, olefins and alkyl and aryl ethers. The alkylating agent used in the process of the invention include haloalkyls, alkyl carbonates and sulphates including dimethyl carbonate and dimethyl sulphate. Preferred halo alkyls include, but are not intended to be limited to, alkyl chloride, alkyl bromide and alkyl iodide. The base used in the process of the invention include, but are not intended to be limited to, alkali metal carbonates such as sodium or potassium carbonate. Most preferred base is potassium carbonate. The alcohol solvent used for the process of the invention is selected from methanol, ethanol, propanol, isopropanol, butanol, isobutanol or pentanol depending upon the alkyl part of the benzoate group attached to the aromatic ring of the phenol. The alcohol solvent for the process is so chosen that the alkyl part of the alcohol is the same as the alkyl part of the benzoate group. The alcohol solvent is often added in excess to enhance the product yield. The process of the invention is carried out in liquid phase for a period of 1 to 8 hours, at a temperature in the range of 70-90 degrees and at a pressure in the range of 2-4 bars. Preferably, the process is carried out for 2-4 hours, in the temperature range of 80 to 900C. The process can be carried out either as a batch process or as a continuous process. The process lead to alkyl alkoxy benzoates in high yields of around 80-100%. The invention is further illustrated by way of the following non limiting example. Example: O-alkylation of 4-hydroxy benzoate 4-hydroxy - ethyl benzoate, 2-bromopropane and potassium carbonate were mixed in molar ratio of 1:1.3:1.3, in an autoclave and stirred in ethanol (Ethanol to 4-hydroxy ethyl benzoate molar ratio being 16-17:1) at a temperature of 85°C for 3 hours. The mixture was cooled, diluted with water and extracted with diethyl ether. The separated ether layer was washed with 10% aqueous sodium hydroxide followed by washings with water and dried over anhydrous sodium sulfate. Solvents were removed on a rotary evaporator to give the desired alkyl alkoxy benzoate as nearly colourless oil in 92% yield. The invention provides a process for obtaining alkyl alkoxy benzoate in high yields at short reaction times, significantly enhancing the process efficiency and reducing the process cost. It has been surprisingly observed that by using an alcohol solvent having an alkyl part same as the alkyl part of the benzoate group attached to the aromatic ring of the phenol, the alkylation is facilitated and high yield of the O-alkylated product is obtained at a short reaction time. Further, the amount of alkylating agent consumed during the process is relatively low, in the order of 1.3 moles of alkylating agent for each mole of phenol. This reduces the process cost and at the same time reduces the waste formed during the process. Furthermore, the alkyl alkoxy benzoate is easily isolated from the solvent and the solvent alcohol is easily recovered. WE CLAIM: 1. A process for synthesis of alkyl alkoxy benzoates having the general formula OR COOR' where R, R is a C1-10 alkyl, R and R being different from one another, in high yields of 80 - 100%, the process comprising reacting a phenol having the formula OH COOR with an alkylating agent in the presence of a base, molar ratio of the phenol, the alkylating agent and the base being 1.0: 1.0-1.4: 1.0-1.5, wherein the process is carried out at a temperature in the range of 70-90°C for a period of 8 - 10 hrs in an alcohol solvent having the formula R OH where R is the same as the R of the benzoate group. 2. The process as claimed in claim 1, wherein the alkylating agent is selected from alkyl halides, dialkyl carbonate or dialkyl sulphate. 3. The process as claimed in claim 1, wherein the alkylating agent is a primary alkyl halide. 4. The process as claimed in claim 1, wherein the base is an alkaline carbonate. 5. The process as claimed in claim 1, wherein the molar ratio of the phenol, the alkylating agent and the base is 1.0:1.3:1.3.

Documents:

540-MUM-2008-ABSTRACT(21-3-2012).pdf

540-MUM-2008-ABSTRACT(24-11-2011).pdf

540-mum-2008-abstract.doc

540-mum-2008-abstract.pdf

540-MUM-2008-CLAIMS(AMENDED)-(21-3-2012).pdf

540-MUM-2008-CLAIMS(AMENDED)-(24-11-2011).pdf

540-mum-2008-claims.pdf

540-MUM-2008-CORRESPONDENCE 13-6-2008.pdf

540-MUM-2008-CORRESPONDENCE 26-6-2008.pdf

540-MUM-2008-CORRESPONDENCE(14-3-2012).pdf

540-mum-2008-correspondence-received.pdf

540-mum-2008-description (complete).pdf

540-MUM-2008-FORM 1 13-6-2008.pdf

540-MUM-2008-FORM 1(24-11-2011).pdf

540-MUM-2008-FORM 13(21-3-2012).pdf

540-MUM-2008-FORM 13(24-11-2011).pdf

540-MUM-2008-FORM 18 26-6-2008.pdf

540-mum-2008-form 2(title page)-(18-3-2008).pdf

540-MUM-2008-FORM 2(TITLE PAGE)-(24-11-2011).pdf

540-mum-2008-form-1.pdf

540-mum-2008-form-2.doc

540-mum-2008-form-2.pdf

540-mum-2008-form-3.pdf

540-MUM-2008-MARKED COPY(21-3-2012).pdf

540-MUM-2008-MARKED COPY(24-11-2011).pdf

540-MUM-2008-POWER OF ATTORNEY 13-6-2008.pdf

540-MUM-2008-REPLY TO EXAMINATION REPORT(24-11-2011).pdf

540-MUM-2008-REPLY TO HEARING(21-3-2012).pdf

540-MUM-2008-SPECIFICATION(AMENDED)-(21-3-2012).pdf

540-MUM-2008-SPECIFICATION(AMENDED)-(24-11-2011).pdf