Expeditious synthesis of ionic liquids using ultrasound and microwave irradiation

Environmentally friendlier preparations of ionic liquids have been developed that proceed expeditiously under the influence of microwave (MW) or ultrasound irradiation conditions using neat reactants, alkylimidazoles and alkyl halides. A number of useful ionic liquids have been prepared and the efficiency of this solvent-free approach has been extended to the preparation of other ionic salts bearing tetrafluoroborate anions that involves exposing N, N'-dialkylimidazolium chloride and ammonium tetrafluoroborate salt to MW irradiation. These novel solventless alternatives circumvent the common drawbacks in widely used preparative methods for ionic liquids that employ volatile organic solvents and relatively much longer reaction time. The utilization of these novel synthetic methods for ionic liquids generation may facilitate truly 'greener' applications of ionic liquids.