Friedel-crafts acylation of aromatic compounds over InCl₃-impregnated aluminium oxide-pillared clay

Abstract

InCl₃-impregnated aluminium oxide-pillared montmorillonite clay (InCl₃/Al-PLC) was synthesized in order to use as a catalyst for Friedel-Crafts acylation of anisole with benzoyl chloride. Aluminium oxide-pillared clay (Al-PLC) was prepared by the intercalation method and calcination at 500°C for 1 h. The impregnation with indium trichloride was done with calcination at 450°C for 4 h. InCl₃/Al-PLC, Al-PLC and montmorillonite clay were characterized using Powder X-ray Diffraction (XRD), N2 adsorption-desorption, X-ray Fluorescence Spectrometry (XRF) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) techniques. The catalytic activity of InCl₃/Al-PLC was compared with those of Al-PLC and montmorillonite. InCl₃/Al-PLC showed significantly higher yield than Al-PLC, and montmorillonite was not catalytic active in this reaction. The optimized condition for the production of 4-methoxybenzophenone was using the 1:3 mole ratio of anisole to benzoyl chloride and InCl3/Al-PLC catalyst with the equivalent of 0.03 mmol InCl₃ in 1,4-dioxane. The reaction was carried out under reflux for 4 h, and gave an excellent yield of 91%. The optimized conditions could be applied to the Friedel-Crafts acylation of different aromatic compounds and acid chlorides with moderate to excellent yields