Experimental Thermodynamic Properties of 1-Butyl-2-methylpyridinium Tetrafluoroborate [b2mpy][BF4] with Water and with Alkan-1-ol and Their Interpretation with the COSMO-RS Methodology

This work provides experimental data on liquid-liquid equilibria in the range 288-328 K and data of H-m(E), and V-m(E) at temperatures of 298.15 and 318.15 K, for binary mixtures corresponding to 1-butyl-2-methylpyridinium tetrafluoroborate, [b2mpy][BF4], with alkanols (methanol to pentan-1-ol) and water. The [b2mpy][BF4] is completely miscible in water, and all the mixtures give positive values of H-m(E) and V-m(E), giving increasing values of excess quantities with temperature. For mixtures with alkanols, values of H-m(E) > 0 are obtained with V-m(E) < 0, endothermic effects accompanied by contraction, with temperature changes represented by (dH(m)(E)/dT)(p) > 0 and (dV(m)(E)/dT)(p) > 0. Experimental data are correlated with a suitable equation and are presented together with those obtained in previous works for another two isomers, [b3mpy][BF4] and [b4mpy][BF4], and the properties of all of them are compared and discussed along with their behavior. The quantum-chemical method COSMO-RS is applied for the first time to predict excess properties of these mixtures' containing ionic liquids, and the results show a significant contribution of hydrogen bond interactions in the behavior of the mixtures studied here, generically referred to as [bXmpy][BF4] (X = 2, 3, 4) + H2O or + C nu H2 nu+1(OH) (nu = 1-5).