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The phase diagrams of the following imidazolium ionic liquids, {1-ethyl-3-methylimidazolium tosylate [EMIM][TOS] + hexane or cycloheptane} and {1-ethyl-3-methylimidazolium ethylsulfate [EMIM][EtSO4] + hexane or benzene}, have been measured. The (solid + liquid) (SLE) and (liquid + liquid) (LLE) phase equilibria of binary mixtures containing {hexyl(2-hydroxyethyl)dimethylammonium bromide (C6Br) + hexane or benzene or an alcohol (ethanol or dodecan-1-ol)} and the salt with a different anion {hexyl(2-hydroxyethyl)dimethylammonium tetrafluoroborate (C6BF4) + hexane or benzene or dodecan-1-ol} have been measured. The effect of anion type (Br- vs BF4 -) on the thermophysical properties of the IL and on the phase behavior is dependent on the strength of the cation−anion interaction in the investigated ILs and is noticeable. The phase diagrams for some novel ammonium ionic liquids, (2-decanoyloxyethyl)dimethylpentyloxymethylammonium trifluoro-acetate [C10OOEtC5OMMMN][CF3COO] or (2-methyloyoxyethyl)dimethylpentyloxyammonium acesulfamate [MOOEtC5OMMMN][Ace] or (2-hydroxyethyl)dimethylundecyloxymethylammonium dicyanamide [C11OMEtOHMMN][(CN)2N], with octan-1-ol are reported. The solvents were chosen as representatives of alkanes, cycloalkanes, aromatic hydrocarbons, and alcohols. The interaction between the most commonly studied ionic liquids and those chosen in this work with typical organic solvents was described. The solubilities were measured by a dynamic method from 250 K to the melting point of the ionic liquid or to the boiling point of water in the bath. The immiscibility of the liquid phase in {[EMIM][TOS] + cycloheptane} was observed. The observed upper critical solution temperature (UCST) in binary mixtures of {[EMIM][TOS] + cycloheptane} and {[EMIM][EtSO4] + hexane or benzene} was limited by the boiling temperature of the solvent. The difference between the solubilities of the three ammonium ionic liquids, [C10OOEtC5OMMMN][CF3COO] or [MOOEtC5OMMMN][Ace] or [C11OMEtOHMMN][(CN)2N], in octan-1-ol is significant:  a simple eutectic system was observed for [C10OOEtC5OMMMN][CF3COO]; LLE was observed for [MOOEtC5OMMMN][Ace]; and an eutectic system with immiscibility in the liquid phase was observed for [C11OMEtOHMMN][(CN)2N]. For the system {[C11OMEtOHMMN][(CN)2N] + octan-1-ol}, the upper critical solution temperature was determined to be 312.9 K. Characterization and purity of the compounds were obtained by water content (Fisher method) and differential scanning microcalorimetry (DSC) analysis. From DSC, melting points, enthalpies of fusion, temperatures, and enthalpies of the solid−solid phase transitions and the temperatures of glass transition of all the investigated ionic liquids were measured.

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Solid + liquid) equilibria (SLE) and (liquid + liquid) equilibria (LLE) for the binary systems ionic liquid (IL) N-butyl-4-methylpyridinium tosylate (p-toluenesulfonate) [BMPy][TOS] + an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or water, or an alkane (hexane, heptane, octane), or benzene, or an alkylbenzene (toluene, ethylbenzene, propylbenzene), or tetrahydrofuran (THF) have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (320 to 390) K. In the case of systems (IL + alkane, or alkylbenzene), the mutual immiscibility with an upper critical solution temperature (UCST) was detected. UV spectroscopy was used to determine the very small compositions of the IL in the alkanes, benzene, and alkylbenzenes (about 1 • 10 -5 IL mole fraction). For the binary systems containing alcohol and water, simple eutectic diagrams were observed with complete miscibility in the liquid phase. As usual, with increasing chain length of the alcohol, the solubility decreases. The basic thermal properties of the pure IL, i.e., melting and glass-transition temperatures as well as the enthalpy of fusion, have been measured using a differential scanning microcalorimetry technique (DSC). Well-known UNIQUAC, Wilson, and NRTL equations have been used to correlate experimental SLE data sets for alcohols and water. For the systems containing immiscibility gaps (IL + alkane, or benzene, or alkylbenzene, or tetrahydrofuran), parameters of the LLE correlation equations have been derived using only the NRTL equation.

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This work is a continuation of our systematic study on thermodynamic properties of 1-n-alkyl-1-methylpiperdinium bis[(trifluoromethyl)sulfonyl]imides homologous series of ionic liquids ([CnC1Pip][NTf2]). Excess enthalpies of mixing (H(E)) of four binary systems containing two ionic liquids, namely [C4C1Pip][NTf2] and [C6C1Pip][NTf2], and two short-chain alcohols, namely ethanol and 1-propanol, were measured by isothermal titration calorimetry. Alcohol-to-ionic liquid and ionic liquid-to-alcohol titration experiments were carried out at temperature T = 298.15 K and atmospheric pressure. The experimental data were modeled in terms of perturbed-chain statistical associating fluid theory (PC-SAFT). Wolbach-Sandler combining rules were adopted in order to account for ionic liquid-alcohol cross-association. The model was applied in a conventional manner (i.e., without any binary corrections) as well as in a novel predictive mode developed previously by our group [Paduszyński, K.; Domańska, U. J. Phys. Chem. B 2012, 116, 5002-5018; Domańska et al. J. Phys. Chem. B 2012, 116, 8191-8200]. The latter approach employs temperature-dependent binary correction fitted to experimental limiting activity coefficient of alcohol in ionic liquid.

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