Activity coefficients at infinite dilution and enthalpies of solution of methanol, 1-butanol, and 1-hexanol in 1-hexyl-3-methyl-imidazolium bis(trifluoromethyl-sulfonyl) imide

Activity coefficients at infinite dilution γi∞ of methanol, 1-butanol, and 1-hexanol in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethyl-sulfonyl) imide ([HMIM][NTf2]) have been determined by gas chromatography using the ionic liquids as stationary phase. The measurements were carried out at different temperatures between 298 K and 396 K. From the temperature dependence of the limiting activity coefficients partial molar excess enthalpies at infinite dilution HiE,∞ of the alcohol in the ionic liquid have been derived. Additionally, enthalpies of solution of the same alcohols in the [HMIM][NTf2] have been measured at T = 298.15 K in the range of low concentrations using titration calorimetry. Results at infinite dilution, HiE,∞, are compared with those indirectly obtained from activity coefficients in infinite dilution γi∞. Within the experimental error of both methods thermodynamic consistency has been confirmed.