New studies in aromatic chloromethylation

Abstract

Chloromethylation reactions of anisole, cumene and trifluoromethylbenzene have been examined using the reagents formaldehyde and hydrogen chloride, in the presence of an extensive range of catalysts. Reaction conditions and choice of catalyst have been optimised to obtain a high ratio of chloromethylated product: diarylmethane product. For anisole this requires the use of titanium tetrachloride as catalyst at O-5ºC; for cumene, zinc chloride as catalyst at 42-48ºC gives the best results. Trifluoromethylbenzene could not be chloromethylated using the HCI/CH(_2)O/ catalyst system. Other alkoxybenzene substrates and chloromethylating reagents have been briefly studied.