GB332983A - - Google Patents

Abstract

332,983. Imperial Chemical Industries, Ltd., and Leicester, F. D. May 17, 1929. Acetic and formic acids; esters.-Acetic and formic acids are concentrated by adsorption of the vapour in active carbon, or, in the case of acetic acid the liquid acid may be treated. The adsorbed acid may be recovered by heating the carbon or by reduction of pressure or both, or by the action of volatile solvents; or the adsorbed acid may be used as such for the production of other bodies, for instance, for the production of esters by reaction with alcohols. In an example, acetic acid of 50 per cent strength is vaporized and the vapour is passed through a tube containing active carbon at. 130‹.: when the adsorption slackens, the admission of vapour is stopped, and the pressure is reduced by a vacuum pump, the acid being collected in fractions of 32 and 96 per cent strength. In another example, acetic acid of 33 per cent strength is passed through a vertical tube filled with active charcoal, the flow being stopped when the exit liquor contains 2 per cent of acid; the column is then allowed to drain, and is subsequently heated to 120‹ C. under vacuum, yielding a first fraction of condensate of 32.5 per cent strength, when the temperature is raised to 200‹ C. and a second fraction of 96 per cent strength is obtained.