Summary 1. a, P-Dichloroethyl ethyl ether, a-chlorobenzyl methyl ether, and triphenylchloromethane react with ketene to give the corresponding substituted acetyl chlorides. No catalyst is required to effect the reaction with a-chlorobenzyl methyl ether or with triphenylchloromethane in nitrobenzene. The reaction with a, P-dichloroethyl ethyl ether and with triphenylchloromethane in benzene takes place only in the presence of a catalyst ...