PROCESS FOR CONTINUOUSLY PURIFYING CRUDE MONOCHLOROACETIC ACID

摘要

1411214 Purification of monochloroacetic acid HOECHST AG 8 May 1974 [11 May 1973] 20242/74 Heading C2C A process for the continuous purification of crude monochloroacetic acid by partially dehalogenating the di- and trichloroacetic acid impurities therein with hydrogen, to form monochloroacetic acid comprises the step of (a) intimately contacting the hydrogen with at least part of the hydrogenated product at a temperature of from 5 to 20‹ C. above the hydrogenation temperature; (b) dehalogenating the di- and trichloroacetic acids by trickling the molten crude acid at a temperature of from 110 to 155‹ C. through a hydrogenation catalyst comprising a noble metal of Group VIII of the periodic table which has been precipitated substantially on the geometric surface of an acid-resistant carrier, in counter current to the hydrogen from step (a); and (c) fractionating the gas mixture obtained in step (b) at a temperature of from 115 to 135‹ C. to produce a partial reflux.