Friedel-Crafts Acylation of Aromatics with Acetic Anhydrideover Nano-Sized Rare Earth Cation Exchanged ZSM-5 Catalysts

Abstract

Friedel-crafts acylation of aromatic compounds used to synthesize aromatic ketones and significance has commercial importance in diverse areas of fine chemical synthesis and pharmaceutical manufacturing industry. Conventionally, acylation reactions are catalysed by corrosive metal halides or mineral acids. The present work reports on the catalytic activity of nanocrystalline ZSM-5 and rare earth metal cation such as La3+, Ce3+ and Nd3+ exchanged ZSM-5 in the liquid phase acylation of veratrole with acetic anhydride. The catalyst was thoroughly characterized for its structure. The nanocrystalline Ce-ZSM-5 displayed highest activity towards the acylation of veratrole. The catalytic performance of Ce-ZSM-5 was used to compare its activity for the acylation of other aromatics; such as toluene, anisole and veratrole. The nanocrystalline Ce-ZSM-5 shows highest activity over nanocrystalline ZSM-5 in acylation reactions of aromatics. It was established that smaller size crystal of Ce-ZSM-5showed superior activity, which is due to the enhanced density of acidic sites along with increased external surface area of smaller crystal which facilitate the activity of the acylation reaction. The catalysts used in this study are reusable without any loss of activity.