A novel chemical redox route was developed for the preparation of water-miscible imidazolium ionic liquids (ILs). In this method, the reaction between 1-alkyl-3-methylimidazolium bromides or 3-butyl-1-phenylimidazolium bromide and the appropriate acid reactant was promoted by the redox reaction between the bromide ion and aqueous hydrogen peroxide, with hex-1-ene as both solvent and bromine scavenger. The residual bromide ion and water contents of the prepared ILs were determined by ion chromatography and the Karl–Fischer test, respectively. This method not only produces water-miscible ILs in high purity and high yield, but also simplifies the reaction conditions in comparison with previous routes.
Key words
ionic liquids - redox reaction - protic acids - imidazolium salts