Hydrophobic Perfluoroalkylsulfonyl Imide Solid Acid as Catalyst of Esterification and Pechmann Condensation

Abstract

Polydivinylbene-bound perfluoroalkylsulfonyl imide polymers with excellent acidity and hydrophobicity were prepared by copolymerization under solvothermal conditions (noted as H-PDVB-x-SSFAI). H-PDVB-x-SSFAI catalyzed the esterification of long chain fatty acid with methanol/ethanol in water, affording 88% conversion, which increased to 95% without additional water within 5~6 h. The catalytic esterification of short chain fatty acid with both primary alcohol and secondary alcohol was carried out smoothly, for example, 87%~92% of conversion was gave for cyclohexanol within 4 h. H-PDVB-x-SSFAI was cycled for at least seven runs with stable catalysis efficiency. On the other hand, H-PDVB-x-SSFAI was used to catalyze Pechmann condensation to give 7-hydroxyl coumarin under 140 °C, affording ca. 90% of average isolated yield, and the catalyst could be cycled for 4 runs. Furthermore, the excellent catalytic performance is attributed to combination of excellent acidity and hydrophobicity.