“ Nafion”-functionalized mesoporous MCM-41 silica shows high activity and selectivity for carboxylic acid esterification and Friedel–Crafts acylation reactions

Abstract

Hybrid organic–inorganic MCM-41 silicas functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nafion were prepared in a simple single step by a condensation reaction between surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro-2-hydroxy-1-trifluoromethyl-ethane sulfonic acid Beta-sultone. The catalysts showed very high activity for the esterification of long-chain fatty acids with ethanol and high-molecular-weight alcohols with essentially complete selectivity at high conversion ( > 95 % ). Acylation of anisole was also possible, with high selectivity for 4-methoxyacetophenone. The catalysts showed more activity conversion than commercial Nafion–silica composite catalysts.