Solvent-free synthesis of benzothiazole-based quaternary ammonium salts: precursors to ionic liquids

A series of 13 benzothiazolium iodide salts have been prepared in solvent-free conditions by optimizing the reaction. An additional 26 benzothiazolium salts with bistrifluoromethanesulfonimide and trifluoromethylsulfonate were prepared via simple metathesis reactions from the iodide precursors. Out of a total of 39 prepared salts, 26 were identified as ionic liquids, with melting points as low as 42 degrees C observed for dodecylbenzothiazolium bistrifluoromethanesulfonimide. All prepared compounds have been characterized using FTIR, H-1, C-13 NMR, and HRMS analyses. The thermal stabilities as well as melting points of these salts were also analyzed.