Friedel-Crafts alkylation of aromatics with benzyl alcohols catalyzed by rare earth metal triflates supported on MCM-41 mesoporous silica

Liquid phase benzylation of aromatics, such as benzene, toluene, p-xylene, mesitylene and naphthalene, with benzyl alcohols was examined using rare earth metal triflates, Sc(OTf)3, Hf(OTf)4, La(OTf)3, and Yb(OTf)4, supported on MCM-41 mesoporous silica. Sc(OTf)3/MCM-41 had the highest catalytic performance among the triflates. The benzylation of benzene proceeds principally to give diphenylmethane (DPM) through direct benzylation with benzyl alcohol (BnOH). Dibenzyl ether (DBE) is formed as a by-product, and it participates in the benzylation with the decrease in BnOH after the hydrolysis.