Effective acetylation of alcohols, phenols and amines over mesoporous aluminophosphate solid acids under solvent free conditions

Abstract

Solid acids such as amorphous aluminophosphates (AlP) and iron aluminophosphates (FeAlP) were synthesized by either precipitation or co-precipitation methods. These solid acids were characterized by BET, NH3-TPD, PXRD, FT-IR and NMR techniques for their surface area, surface acidity, crystallinity and functionality. AlPs and FeAlPs were found to be mesoporous in nature. The catalytic activity of these solid acids was determined in acetylation of various alcohols, phenols and amines with acetic anhydride under solvent free conditions. The reaction conditions were optimized by varying the parameters such as molar ratio of the reactants, reaction temperature and amount of the solid acid catalyst. Among the solid acids, FeAlP consisting of 0.025 mol% Fe showed good catalytic activity in the acetylation reaction. These solid acid catalysts can also be reused for acetylation at least for five reaction cycles without any appreciable loss of catalytic activity.