Acetylation of aromatics over acid zeolites: seeking for a viable alternative to Friedel-Crafts catalysts

Three acid zeolites (H-BEA, H-FAU, and H-MWW) were used as catalysts for acetylation in batch reactors with acetic anhydride of five aromatic compounds (benzenic and naphthalenic derivatives). The substrate reactivity is mainly governed by electronic factors (the nature of the substituents and degree of ring activation), but steric effects also play a relevant role when the reaction takes place in a narrow micropore system. In general, H-FAU was the most active catalyst, whereas with H-BEA remarkable steric constraints were observed. H-MWW showed good stability toward deactivation and an interesting activity of the sites located on the external surface.