Gas phase acid chloride prodn. - from acid and phosgene in presence of active carbon catalyst

摘要

Acid chlorides in the gas phase are prepd. by reacting acid vapour with gaseous COCl2 in the presence of active C, the molor ratio of COCl2 to acid being > 1.5:1 and the reactor dia. being >=10 times the dia. of the active C grains. The molor ratio is pref. 2-4 and the reaction temp. may be 10-50 degrees C higher than the b.pt. of the acid. The active C is pref. of vegetable origin of 1-2 mm dia. e.g. cocoa black. Excess COCl2 may be recycled to the reactor. The process may be used for prodn. of linear or branched, satd. or unsatd. opt. halogenated aliphatic acids and aromatic acids. The prod. is obtd. in purer form and it is possible to prepare monochloracetyl chloride by this method.