* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
General procedure: To a solution of the crude 1-butyl-3-methylimidazoliumbromide, obtained from the above reactions,in acetone (70 mL) was added hexafluorophosphoric acid (10.90 g,100.0 mmol). The reaction mixture was stirred for 24 h at room temperature. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding 1-Butyl-3-methylimidazolium hexafluorophosphate. Same procedure was used except that trifluoro methane sulphonic acid (15.08 g,100.0 mmol) was used instead of hexafluorophosphoric acid. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding imidazolium trifluromethanesulphonate.1-Butyl-3-methylimidazolium tetrafluoroborate was also prepared using the same procedure as above except that tetrafluoro boric acid (15.08 g, 100.0 mmol) was used in place of hexafluorophosphoric acid. Progress of the reaction was measured by TLC. Completion of the reaction was confirmed by 1HNMR.
In neat (no solvent); at 100℃; for 0.333333h;Microwave irradiation;
General procedure: a mixture of 1-methylimidazole (0.4105 g, 5 mmol), 1-bromobutane (0.6850 g, 5 mmol) was heated under microwave irradiation (or conventional heating) in a 10 mL pressurized glass tube fitted with a Teflon-coated septum at 80 C for 20 min. Then, LiOTf (0.78 g, 5 mmol) was added and the mixture was irradiated at 100 C for 20 min. After cooling, the mixture was diluted with MeCN (5 mL), and after removal of the precipitated salt LiBr, the filtrate was then filtered through Celite. The crude product was washed with Et2O and concentrated to give a colorless to pale yellow liquid (1.382 g, 96 % yield). The [BMIM]OTf was dried under reduced pressure. The purity and authenticity of the ionic liquids were confirmed by 1H and 13C NMR spectroscopy.
In acetone; acetonitrile; at 60℃; for 24h;
1-Butyl-3-methylimidazolium bromide was dissolved in acetone/acetonitrile (50:50) and an equimolar amount of LiTfO in acetone was added. The mixture was stirred for 1 day at 60 C and then filtered. The solvent was removed under reduced pressure and the crude product dissolved in CH2Cl2. Upon cooling to 5 C most of the Li halide precipitated and the precipitate was filtered off. The remaining solution was washed halide-free with deionized water (AgNO3 test) and filtered over a column filled with neutral Al2O3 and activated charcoal. The residual organic phase was freed from solvent under reduced pressure and dried under dynamic vacuum for 1-2 days at 80-90 C.