Diarylmethane formation in the reaction of various metal acetates with alkylbenzenes in the presence of perchloric acid

Abstract

Treatment of alkylbenzenes with various metal acetates (Mn^III, Fe^III, Co^III, Cu^II, and Pb^IV) in acetic acid containing perchloric acid at reflux temperature affords diarylmethanes as main products: Mn^III and Fe^III acetates are found to be better reagents than the others, and have comparable activity for diarylmethane formation. Reactions with Mn^III acetate–perchloric acid differ from those with Fe^III perchlorate (reported previously) in the following ways: the presence of oxygen increases the amount of benzylic aldehyde produced in the former and of diarylmethane produced in the latter reaction; both disproportionation and polymerization, which occur in the latter reaction, are minimized in the former case, making the work-up procedure easier.