Acylation of aromatic compounds on H-Beta zeolites

Friedel-Crafts acylation of anisole by acetic anhydride and the Fries rearrangement of phenyl acetate were investigated in the liquid phase using the H-form of various zeolites. Zeolite Beta was found to be the most active catalyst for acylation reactions compared to Y- and ZSM-5 zeolites. The reactions were found to be controlled by mass transfer limitations caused by coke deposition. Two types of coke (extractable and non-extractable) were identified. Combining liquid phase reaction with continuous extraction of the catalyst with refluxing reaction mixture in a Soxhlet-like reactor led to a higher conversion of phenyl acetate in the Fries rearrangement. The ratio of protonated to acylated surface centres strongly determines the selectivity. The formation of o-hydroxyacetophenone proceeds both via intramolecular rearrangement and intermolecular acylation. On the other hand, p-hydroxyacetophenone is formed entirely by intermolecular acylation. (C) 1999 Elsevier Science B.V. All rights reserved.