P₂O₅/Al₂O₃ as an Efficient Heterogeneous Catalyst for the Acetylation of Alcohols, Phenols, Thiols, and Amines Under Solvent-Free Conditions

Abstract

A convenient, rapid, and efficient method for the acetylation of alcohols, phenols, thiols, and amines has been developed by using acetic anhydride in the presence of a catalytic amount of P₂O₅ /Al₂O₃ under solvent-free conditions at room temperature. This reaction was studied under different conditions, and several solvents were examined for this conversion. However, in terms of reaction time and yield, it was found that the best result was obtained when the reaction was carried out under solvent-free conditions. Racemization of optically active alcohols and epimerization of sugars were not observed. The use of nontoxic and inexpensive materials, simple and clean workup, short reaction times, and good yields of the products are the advantages of this method.

Keywords:

• Acetylation
• alcohols
• amines
• P₂O₅/Al₂O₃
• thiols

ACKNOWLEDGMENTS

We gratefully acknowledge the funding support received for this project from the Islamic Azad University of Fasa and Isfahan University of Technology (IUT).

Notes

^a The yields refer to the isolated pure products.

^b The reaction was carried out in 5 mL of solvent at rt.

^a The yields refer to the isolated pure products.

^b The products were characterized from their spectral (IR, ¹H NMR) data and comparison with authentic samples.

^c The substrate was reacted with 2 equiv of Ac₂O per OH, SH, or NH₂ group unless otherwise stated.

^d Acetic anhydride was used as a solvent.

^e The substrate was reacted with 3 equiv of Ac₂O.