Activity coefficients at infinite dilution of organic solutes in N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([CnPY][NTf2], n = 2, 4, 5) using gas–liquid chromatography

The activity coefficients at infinite dilution, γi∞ for both polar and non-polar solutes in the ionic liquids N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([CnPY][NTf2], n = 2, 4, 5) have been determined by gas–liquid chromatography using the ionic liquid as the stationary phase. The measurements were carried out at the temperatures from (303 to 353) K. The partial molar excess enthalpies at infinite dilution HiE,∞ of the solutes in the ionic liquids were also derived from the temperature dependence of the γi∞ values. The values of the selectivity for the hexane/benzene and cyclohexane/benzene separation problems were calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literatures.