GB478246A - Improvements in or relating to the manufacture of organic acids and esters - Google Patents

Abstract

Carboxylic acids and esters are made by reaction of a saturated monohydric aliphatic alcohol with carbon monoxide in the presence of a boron halide, e.g. boron fluoride, the reaction when carried out in the liquid phase being effected substantially in the absence of water. The reaction may be effected in the liquid phase from room temperature up to about 350 DEG C., preferably 180--240 DEG C., and from atmospheric pressure up to 1000 atmos. or more, preferably 350--750 atmos., or in the vapour phase, preferably at 200--400 DEG C., and at 25--900, preferably 350--700 atmos. Substances promoting the activity of the condensing agent such as metals or metal oxides, e.g. nickel or nickel oxide, may be present. The vapour phase reaction is advantageously carried out in the presence of water vapour. The reactant vapours may be led over activated charcoal. Carbon monoxide from commercial sources may be used, preferably after removal of sulphur compounds, metal carbonyls and like impurities but containing inert gases such as nitrogen. Suitable alcohols comprise methyl, ethyl, propyl, butyl, including the secondary and tertiary alcohols, hexyl, and octyl alcohols. The reaction apparatus may be of acid-resisting alloy steels or chromium or silver plated inside. In examples: (1) boron fluoride is absorbed in a molecularly equivalent weight of methanol in an autoclave. Carbon monoxide is added till the pressure is 700 atmos. and temperature maintained at 200 DEG C. to form acetic acid; (2) ethanol similarly gives propionic acid; (3) a gaseous mixture containing 85 per cent by volume of CO, and 5 per cent each of C2H5OH, H2O, and H2, is passed with about 2 per cent BF3 over activated charcoal at about 325 DEG C. and 700 atm. to yield acetic acid. Specification 310,438, [Class 2 (iii)], is referred to. The Specification as open to inspection under Sect. 91 comprises the use as condensing agents of hydrofluoboric acid or oxygenated acids obtained by reacting HF with boric acid or borates, e.g. as described in Specification 478,085, [Group III]. It includes also the preparation of polycarboxylic acids from polyhydroxy alcohols such as ethylene or propylene glycol or glycerine. This subject-matter does not appear in the Specification as accepted.