A new class of solvents for CCC: The room temperature ionic liquids

Room temperature ionic liquids (RTILs) are salts with melting point close or below room temperature. Changing the nature of the anion or the cation produces a new salt that may or may not be a RTIL. The physico chemical properties of RTILs are briefly reviewed. The partitioning of 38 aromatic derivatives with acid, base, or neutral functionalities was studied between the biphasic liquid system 1-butyl-3-methyl imidazolium hexafluorophosphate (BMIM PF6) and water. It was found that the viscosity of pure RTILs is too high for direct use as a liquid phase in countercurrent chromatography (CCC). The addition of a third solvent was needed to decrease viscosity. The ternary phase diagrams of BMIM PF6-water and acetonitrile, methanol, ethanol, 1-propanol and 2-propanol are presented in mass and mole percentages. The organic solvent-RTIL-water systems form two liquid phases with a viscosity low enough to allow CCC operation which was not done, due to the low amount of RTIL prepared.