GB585996A - Improvements in or relating to the production of aceto acetic esters and their homologues - Google Patents

Abstract

Alkyl esters of aceto-acetic acid and its homologues are prepared by passing a compound of the general formula R1CH(OH).CH2.COOR2, in which R1 and R2 represent saturated alkyl groups having not more than four carbon atoms, over a metal dehydrogenating catalyst at a temperature between 200 DEG and 400 DEG C. in the substantial absence of oxygen. The preferred catalysts are metallic copper, silver and brass, generally in the form of gauze or filings, but, if desired, on a carrier such as magnesium oxide, magnesite, aluminia or partially oxidized metals. Inert gases, for example, nitrogen or inert organic substances, or unsaturated organic substances such as methyl crotonate which serve as hydrogen acceptors for the hydrogen formed, may be present. In examples: (1) methyl beta-hydroxy butyrate is passed through a heated tube at 330 DEG C. containing a copper catalyst prepared by reducing copper oxide wire with hydrogen, yielding methyl aceto-acetate and some acetone; by reacting at 420 DEG C. or in presence of oxygen only minor amounts of the aceto-acetate, but in the former case, large amounts of acetone and methyl crotonate are obtained; (3) the experiment of (1) above is repeated, using brass gauze as catalyst and results are given showing the effect of various temperatures on yields. Specification 361,153 and U.S.A. Specifications 1,614,195 and 1,890,277 are referred to.