GB828371A - Alkyl 3-alkoxypropionates - Google Patents

Abstract

Alkyl 3-alkoxy propionates are prepared by contacting a symmetrical dialkoxy methane with ketene under substantially anhydrous conditions at a temperature in the range of from 10 DEG to 60 DEG C. and in the presence, as catalyst, of not more than 5% by weight of BF3 based on the dialkoxy methane. Generally a molar ratio of ketene : dialkoxy methane of from 0.5 : 1 to 0.9 : 1 is used. The catalyst may be present in the form of its diethyl ether complex. Suitably, the ketene is bubbled into the dialkoxy methane, if desired under elevated pressure. The reacted mixture is then neutralized and fractionally distilled to recover the ester. Examples describe the conversion of dimethoxy methane, diethoxy methane and di-n-butoxy methane into methyl methoxy, ethyl ethoxy and butyl butoxy propionates. Di-isopropoxy- and diisobutoxy methanes are also mentioned. Comparative experiments show the reduction in yield obtained by operating at -5 DEG to 0 DEG C. The first Provisional Specification describes the reaction of ketene with dialkoxy methanes under substantially anhydrous conditions in the presence of at least 5% by weight of a BF3/diethyl ether complex based on the dialkoxy methane at temperatures of, for example, - 5 DEG to 40 DEG C. The second Provisional Specification specifies for the same reaction the use of not more than 5% by weight of the BF3-ether complex based on the dialkoxy methane and of temperatures above about 300 DEG C. U.S.A. Specification 2,436,286 is referred to.