IL134110A - Process for preparing cyanoacetic esters - Google Patents

Abstract

Preparation of 1-10 carbon alkyl, 3-10 C alkenyl or aryl-(1-4 C)-alkyl cyanoacetates comprises reacting an alkali cyanoacetate with an alk(en)yl or arylalkyl halide (II) in an aqueous-organic 2-phase system in the presence of a phase transfer catalyst. Preparation of 1-10 carbon (C) alkyl, 3-10 C alkenyl or aryl-(1-4 C)-alkyl cyanoacetates of formula (I) comprises reacting an alkali cyanoacetate with an alk(en)yl or arylalkyl halide of formula RX (II) in an aqueous-organic 2-phase system in the presence of a phase transfer catalyst. R = 1-10 C alkyl, 3-10 C alkenyl or aryl-(1-4 C)-alkyl; X = chlorine (Cl), bromine (Br) or iodine.

Description

PROCESS FOR PREPARING CYANOACETIC ESTERS Description The invention relates to a process for preparing cyanoacetic esters of the general formula in which R is or Here and to be understood as any linear or branched secondary or tertiary group having 1 to 10 carbon in particular groups such as nonyl or is to be understood as the corresponding groups having 3 to 10 carbon atoms and at least one double where the double bond is advantageously separated from the free valency by at least one saturated carbon These in groups such as The customary synthesis of cyanoacetic esters is carried out by cyanidation of sodium chloroacetate in aqueous followed by an esterification the appropriate where the water formed is distilled off An essential disadvantage of this process is the fact that the water has to be removed after since the subsequent esterification is only possible under substantially On an industrial this is usually carried out by evaporating the Since the sodium cyanoacetate which is formed as intermediate is moreover highly a for its esterification in water as the solvent is it was an object of the present invention to develop a process where the aqueous solution of sodium cyanoacetate which is obtained after cyanidation can be esterified According to the this object is achieved by the process herein It has been found that cyanoacetic esters of the general formula in which is can be prepared by reacting an alkali cyanoacetate in an aqueous system in the presence of a transfer catalyst with a halide the general formula in which R is as defined above and X is bromine or The organic phase used can be the halide on its own or in a mixture with an organic The alkali metal cyanoacetate which is preferably used is sodium The sodium cyanoacetate is particularly preferably employed in the form of the aqueous solution obtained in the reaction of sodium c loroacetate with X is preferably chlorine or The catalyst which is preferably employed is a quaternary ammonium Particularly preferred quaternary ammonium salts are the or in particular the chlorides and Preference is also given to using methyl ether or chlorobenzene as solvent in the organic The examples below illustrate the practice of the process according to the invention without limiting All reactions were carried out in an autoclave having an internal volume of about 250 The yield was determined by gas chromatography with the aid of an internal Example 1 Methyl cyanoacetate g of methyl chloride were introduced into a mixture of g of cyanoacetic g of sodium hydroxide and g of tetrabutylammonium bromide in 15 ml of methyl The reaction mixture was heated to an internal temperature of 100 bath temperature over a period of 30 during which the pressure in the autoclave increased from 4 to 10 After h at the autoclave was cooled and The pH of the aqueous phase was adjusted from to using g of 1 M aqueous sodium hydroxide the organic phase was separated off and the aqueous phase was extracted with methyl ether The combined organic phases were dried with sodium admixed with dimethyl succinate internal and analysed by gas g of methyl cyanoacetate were Comparative Example 1 Methyl cyanoacetate The method described in Example 1 was but without addition of tetrabutylammonium The yield of methyl cyanoacetate was only Example 2 Ethyl cyanoacetate A mixture of g of cyanoacetic g of sodium g 5 of ethyl bromide and g of tetrabutylammonium bromide in 15 ml of was heated to an internal temperature of over a period of 30 min and stirred at 100 bath temperature for The reaction mixture was then the phases were separated and the aqueous phase was extracted with methyl ether The combined organic phases were dried with sodium admixed with dimethyl succinate and analysed by gas g of ethyl cyanoacetate were insufficientOCRQuality

Claims (7)

134110/2 - 5 - Claims

1. Process for preparing cyanoacetic esters of the general formula in which R is Ci-10-alkyl or C3-i0-alkenyl, characterized in that an alkali metal cyanoacetate is reacted in an aqueous/organic two-phase system in the presence of a phase-transfer catalyst with a halide of the general formula R—X (II), in which R is as defined above and X is chlorine, bromine or iodine.

2. Process according to Claim 1, characterized in that the alkali metal cyanoacetate used is sodium cyanoacetate.

3. Process according to Claim 2, characterized in that the sodium cyanoacetate is used in the form of the aqueous solution obtained in the reaction of sodium chloroacetate with sodium cyanide.

4. Process according to any of Claims 1 to 3, characterized in that X is chlorine or bromine.

5. Process according to any of Claims 1 to 4, characterized in that the phase-transfer catalyst used is a quaternary ammonium salt.

6. Process according to Claim 5, characterized in that the quaternary ammonium salt used is a tetra-n-C4-i0-alkylammonium, benzyltri-n-C1-8-alkylammonium or methyltri-n-C4_ifi-alkylammonium halide, preferably chloride or bromide.

7. Process according to any of Claims 1 to 6, characterized in that the organic phase comprises tert-butyl methyl ether or chlorobenzene as solvent.