Synthesis and property of imidazolium oxidative-thermoregulated ionic liquids

A series of novel imidazolium oxidative-thermoregulated bifunctional ionic liquids (ILs) have been synthesized by introducing the thermoregulated structural unit into imidazolium cation and using heteropolyanion as the anion of ILs. The structures of these new type of task-specific ionic liquids (TSILs) are characterized by FT-IR and ¹H NMR. The thermostability of ILs is analyzed by thermogravimetry. The thermoregulated properties of ILs in aqueous and organic solvents are mainly investigated. These ILs have the corresponding cloud points (CPs) in aqueous. The effects of IL concentration, polymerization degree, inorganic additives and organic additives on the CP are studied. IL/DMF/n-heptane or n-octane biphasic system has the corresponding critical solution temperature (CST), and has the feature of “homogeneous at high temperature, heterogeneous at low temperature”. The effects of IL dosage and polymerization degree on the CST are given. IL/DMF/n-octane thermoregulated biphasic system has been successfully applied for catalytic oxidative desulfurization of model fuels. This study opens up a new way for catalytic oxidation to achieve an integration of homogeneous catalysis and heterogeneous separation.