Synthesis of Ionic Liquids [BMIM]BF₄ and [BMIM]PF₆ under Microwave Irradiation by One-Pot

Ionic liquids 1-brutyl-3-methylimidazolium Tetrafluoroborate [BMIM]BF4 and 1-brutyl-3-methylimidazolium hexafluorophosphate [BMIM]PF6 were synthesized directly from 1-butylbromide, 1-methylimidazole, sodium tetrafluoroborate or hexafluorophosphate using microwave by one-pot under solvent-free conditions in an unmodified household oven. This method requires only a few minutes of reaction time, in contrast to the several hours needed using conventional methods by two pots that requires a lot of organic solvent. The reaction yield of ionic liquids with intermittent microwave heating is much higher than that of ionic liquids with conventional microwave heating. Thus the intermittent microwave heating is a good method for the reaction. The yield of the two ionic liquids increased slightly with increment of molar ratio of sodium tetrafluoroborate or potassium hexafluorophosphate.