Ultrasound assisted synthesis of imidazolium salts: An efficient way to ionic liquids

[Display omitted] •Imidazolium salts with ionic liquid properties were synthesized.•Imidazole derivative N1-alkylation under ultrasound irradiation were synthesized.•Imidazole derivative N3-quaternization under ultrasound irradiation were synthesized.•Reaction time was substantially reduced.•The amount of the consumed solvent was substantially reduced. In this study a straightforward and efficient approach concerning synthesis of 1,3-diazole derivatives under ultrasound (US) irradiation as well as under conventional thermal heating (TH) is presented. N-alkylation under US irradiation may be considered environmentally friendly in terms of higher yields, smaller amounts of solvent used and an overall energy efficiency due to a substantial reduction of reaction times. A comparative study of ultrasound vs. conventional conditions has been performed. Overall, the use of US proved to be more efficient than TH. A possible explanation concerning the different behavior of imidazole and benzimidazole in the N1-alkylation reactions under US irradiation was proposed.