Benzylation of arenes

Because diphenylmethanes unexpectedly resulted from reaction of alpha,alpha'-dichloro-p-xylene with arenes over aluminum amalgam, a study was made of such benzylation reactions with Friedel-Crafts catalysts. Ferric and antimony chlorides gave the expected products, but aluminum chloride-like aluminum amalgam-gave mainly diphenylmethanes. With the two sets of catalysts, benzyl chlorides also gave different products. Aluminum amalgam appears to function by the steady formation of small amounts of aluminum chloride. Benzylation reactions are apparently less unequivocal than heretofore supposed.