Ionic Liquids’ Cation and Anion Influence on Aromatic Amine Solubility

The mutual solubility of aniline and a series of imidazolium based ionic liquids with bis(trifluoromethylsulfonyl)amide, chloride, dicyanamide, tetrafluoroborate, and hexafluorophospate anions were studied. The produced results show the potential in the new solvent systems which can be used in amine chemistry. The liquid–liquid equilibrium (LLE) and solid–liquid equilibrium (SLE) measurements were performed using a dynamic (synthetic) method. The mutual solubility of aniline in bis(trifluoromethylsulfonyl)amide and hexafluorophosphate ionic liquids was complete in the examined range of temperatures. The solubility of remaining studied ionic liquids decreases with the decrease of Kamlet–Taft basicity of ionic liquid anion. In other words, the solubility was the lowest for a chloride ionic liquid and increases for dicyanamide and for tetrafluoroborate ionic liquids. Additionally, the increase of the alkyl chain length of the IL cation effects negatively the solubility of aniline in the investigated ionic liquids.