Metal chlorides supported solid catalysts for F-C acylations of arenes

Abstract

A series of metal chlorides supported solid catalysts were prepared by simple wet impregnation method. Their catalytic performances for Friedel-Crafts acylation of toluene with benzoyl chloride were evaluated and the excellent results were obtained over FeCl₃/SiO₂. These catalysts were characterized by BET, NH₃-TPD and FT-IR of pyridine adsorption to clarify the structure-activity relationship. It was found that FeCl₃/SiO₂ has larger pore size and pore volume than other catalysts, which increased the accessibility of the catalyst. In addition, FeCl₃/SiO₂ exhibited higher molar ratio of Lewis acid sites and Brφnsted acid sites, which might be another reason for the increase of toluene conversion. Furthermore, the reaction parameters, including temperature, time and molar ratio, were optimized. Under the optimized conditions, 91.2%, conversion and 82.0%, selectivity were obtained. Meanwhile, the generality of the catalyst was demonstrated by the acylations of alkyl substituted aromatics. Finally, the catalyst was reused for four runs with slight loss in catalytic activity, which attributed to the drain of the active component.

Keywords

acylation / heterogeneous catalyst / silica gel / ferric chloride

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