Regioselective acylation of anisole with carboxylic acids over HZSM-5 catalyst

Over a HZSM-5 catalyst, the liquid-phase acylation of anisole with carboxylic acid gave the phenyl carboxylic ester at lower temperatures (< 403 K) while at higher temperatures (> 423 K) 4-acyl anisole was the predominant product.