(Vapour + liquid) equilibria, (VLE) excess molar enthalpies and infinite dilution activity coefficients of selected binary systems involving n-hexyl pyridinium bis(trifluoromethylsulphonyl)imide ionic liquid: Experimental and predictions using modified

(Vapour + liquid) equilibria (VLE), excess enthalpies (HE) and infinite dilution activity coefficients (γ∞) were measured for ethanol, propan-1-ol, butan-1-ol and cyclohexane in the presence of the ionic liquid (IL), n-hexyl pyridinium bis (trifluoromethylsulphonyl) imide [HPy][NTf2]. Except for some limiting activity coefficients values, qualitative agreement was generally observed between the reported values and modified UNIFAC (Dortmund) predictions. Experimental results also suggest that the IL studied is less attractive as a separation solvent for the cyclohexane/benzene system than most of bis (trifluoromethylsulphonyl) imide-based ILs. Excess enthalpy values suggest endothermic behaviour when mixing [HPy][NTf2] with the solutes. All the reported results can be used to derive new modelling approaches as well as to improve existing thermodynamic models (including that used in this study) for the description of mixtures involving pyridinium-based ILs.