A Solventless Process for the Synthesis of Imidazolium-Based Ionic Liquids

Benzyl imidazole (1a) was successfully synthesized from the N-alkylation of imidazole with benzyl bromide. The product (1-benzylimidazole) was further alkylated using neat butyl bromide to yield an imidazolium ionic liquid, (1-Benzyl-3-butylimidazoliumbromide (2a)). Similarly, 1-methylimidazole (1b) was reacted with benzyl bromide to yield 1-Methyl-3-butylimidazolium bromide (2b). The synthesized compounds were characterized by spectroscopic techniques and elemental compositions were established on the basis of C, H, N elemental analyses. Proton NMR of both ionic liquids 2a and 2b reveals the presence of downfield signals at 10.08 and 11.681 ppm respectively, which were assigned to the C-2 proton of the imidazole rings in the respective 2a and 2b confirming the successful synthesis of the two ionic liquids.