Solubility of 1-Alkyl-3-methylimidazolium Hexafluorophosphate in Hydrocarbons

The solubilities of 1-ethyl-3-methylimidazolium hexafluorophosphate, [emim][PF 6 ], in aromatic hydrocarbons (benzene, toluene, ethylbenzene, o -xylene, m -xylene, p -xylene) and of 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF 6 ], in the same aromatic hydrocarbons, in n -alkanes (pentane, hexane, heptane, octane), and in cyclohydrocarbons (cyclopentane, cyclohexane) have been measured by a dynamic method from 290 K to the melting point of the ionic liquid or to the boiling point of the solvent. The melting point, enthalpy of fusion, and enthalpies of solid−solid phase transitions were determined by differential scanning calorimetry (DSC). The solubilities of [emim][PF 6 ] and [bmim][PF 6 ] in aromatic hydrocarbons decrease with an increase of the molecular weight of the solvent. The differences of the solubilities in o -, m -, and p -xylene are not significant. The intermolecular solute−solvent interactions are very small. The liquidus curves were correlated by means of the UNIQUAC and NRTL equations, utilizing parameters derived from the solid−liquid equilibrium. The average root-mean-square deviation of the solubility temperatures for all solvents was 0.41 K and depended on the particular equation used.