Synthesis and investigation of physicochemical properties of dicationic ionic liquids

A series of dicationic ionic liquids (ILs) including [C4(MIM)2] [PF6] 2, [C5(MIM)2] [PF6] 2, [C6(MIM)2] [PF6] 2and [C4(PYR)][PF6]2 were synthesized. Their thermal stability and melting points were analyzed. It was found that dicationic ILs presented important implications in the design of homogeneous and heterogeneous system with water. A homogeneous system of dicationic ILs with water could be formed at a relatively high temperature and then a heterogeneous system was formed when the solution was cooled to a low temperature. The recovered ILs by altering the temperature were obtained in high yields of [C46]2(0.98 g), [C5(MIM)2][PF6]2 (0.97 g), [C6(MIM)2][PF6]2 (0.98 g) and [C4(PYR)2][PF6]2 (0.94 g). In the other hand, [C4(MIM)2][PF6]2 and [C5(MIM)2][PF6]2 exhibited good solubility in acetonitrile and acetone. A homogeneous system could be achieved with imidazolium-based ILs with a relatively low amount of water and acetonitrile at room temperature. All of the properties of dicationic I...