Fluid-Phase Behavior of {1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl) Imide, [C6mim][NTf2], + C2−C8 n-Alcohol} Mixtures: Liquid−Liquid Equilibrium and Excess Volumes

In the frame of the IUPAC Project entitled Thermodynamics of ionic liquids, ionic liquid mixtures, and the development of standarized systems, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C 6 mim][NTf 2 ], was selected as the “model” ionic liquid to perform round-robin measurements on a series of ionic liquid properties. In this work, the temperature−composition liquid−liquid equilibria of this ionic liquid with linear alkan-1-ols, C n H (2 n +1) OH, with n = 4, 5, 6, and 8, were determined at a nominal pressure of 0.1 MPa and up to 50 MPa for n = 4, 5, and 6. Excess molar volumes, V E, of mixtures of this same ionic liquid with linear alkan-1-ols, C n H 2 n +1 OH, with n ranging from 2 to 5, were measured at a nominal pressure of 0.1 MPa. The consistency between the two sets of experimental data (phase diagrams and V E ) was analyzed from a theoretical perspective; we noticed that as the alkyl chain length, n, of the linear alcohol varies both the pressure dependence of the phase diagrams and the critical excess molar volume change sign.