Method of preparation of halogen-free ionic liquids and ionic liquids prepared in this manner

摘要

The reaction of N-alkylimidazol with alkyl sulfonates, at room temperature, favors the production of 1,3-dialkylimidazolium alkane-sulfonates as crystalline solids at high yields. The alkane-sulfonate anions may be easily substituted by a series of other anions [BF₄, PF₆, PF₃(CF₂CF₃)₃, CF₃SO₃ and (CF₃SO₂)₂N] through simple anion, salt, or acid reactions in water at room temperature. The extraction with dichloromethane, filtration, and evaporation of the solvent, allows the production of the desired ionic liquids at a yield of 80-95%. The purity of these ionic liquids (in some cases 99.4%) is performed using the intensity of ¹³C satellite signals from the magnetic resonance spectrums of the N-methyl imidazolium group as an internal standard.