Abstract Several Brønsted acidic functional ionic liquids (FILs) with an alkane sulfonic acid group were synthesized. These FILs as dual solvent-catalysts for Nipagin esterification reactions were investigated. The results indicated that [HSO3-pMIM] HSO4 has the best catalytic activity and recyclability among the various kinds of FILs investigated, and its structure was characterized by infrared and NMR. The [HSO3-pMIM] HSO4 could be ...
