Benzylation of benzene and substituted benzenes by benzyl chloride over InCl 3, GaCl 3, FeCl 3 and ZnCl 2 supported on clays and Si-MCM-41

Abstract

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl 3, GaCl 3, FeCl 3 and ZnCl 2 supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl 3, GaCl 3 and FeCl 3 showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl 3, GaCl 3, FeCl 3 or ZnCl 2 seems to play a very important role in the benzylation process. Among the catalysts, the InCl 3/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl 3 (or GaCl 3)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed.