Preparation and characterization of WO3 bonded imidazolium sulfonic acid chloride as a novel and green ionic liquid catalyst for the synthesis of adipic acid

Abstract

A novel nano WO₃-bonded imidazolium-sulfonic acid chloride (WO₃-IL) was prepared, and characterized by FT-IR, XRD, SEM, TEM, EDX and BET. The as synthesized WO₃ nanoparticle supported ionic liquid is studied as a heterogeneous catalyst for the liquid phase oxidation of cyclohexene to adipic acid. Apart from cyclohexene, a few other six-eight membered cyclic alcohols and ketones are converted into their dicarboxylic acids in high yields and in short reaction times employing the same reaction protocol. The synergy between the WO₃ and ionic liquid is assumed to play a significant role towards its very high catalytic activity. The recyclability of the catalyst is proved to be noteworthy as the catalyst exhibits no significant change in its catalytic activity even after five cycles of reuse.