In this article, we study the behavior of an ionic liquid (IL) derived from pyridinium, 1-butyl-3-methylpyridinium tetrafluoroborate [b3mpy][BF4], in mixtures with water and with the first alkanols of the series from methanol to butan-1-ol, at the temperatures of (298.15 and 318.15) K. First, the miscibility regions with the alkanols were established at these two temperatures, determining experimentally the liquid−liquid equilibria and the upper critical solution temperature (UCST) for each binary mixture, confirming the quasiexponential variation of the UCST with the alkanol chain. The enthalpies were determined experimentally with a newly designed calorimetric cell, and the excess molar volumes were determined from densities, at (298.15 and 318.15) K. In all cases, the are positive with (d /dT)p > 0, whereas the are negative for mixtures with alkanols but positive for the mixture of IL + water. The thermal coefficient (d /dT)p > 0 was also positive in all cases. All data were correlated with a suitable polynomial equation, and the area and volume parameters of [b3mpy][BF4] were calculated. Finally, we give an interpretation of the results and of the behavior of the mixtures.

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For this work, V m E and H m E have been measured at a temperature of 298.15 K and at atmospheric pressure for a set of binary mixtures composed of seven alkyl ethanoates (from methyl to octyl, except heptyl) and six 1-chloroalkanes (C 4 to C 9 ). Of the 42 binary mixtures, measurements have only been made for systems for which the excess quantities have not been published previously. Except for the octyl ethanoate +1-chlorobutane system, with V m E < 0, and hexyl ethanoate+1-chlorobutane, with V m E ≈ 0, the mixtures present expansive effects. In the case of the enthalpies, methyl ethanoate+1-chloroalkane mixtures are all endothermic and evolve toward H m E < 0 as the alkanolic part of the ethanoate increases, and mixtures of octyl ethanoate+1chloroalkane are all totally exothermic. The COSMO-RS model, based on quantum chemical calculations, has been used to explain the behavior of these mixtures, which estimate the enthalpic effects as a result of the inter/intramolecular interactions of the two types of ester/chloroalkane molecules. The results obtained with the COSMO-RS give a good qualitative prediction with an explanation of the different effects that determine the behavior of these mixtures, especially the influence, in both the pure substance and the mixture, of the increased chain length in both types of compound. Application of two different versions of the UNIFAC method gives acceptable results, although with the original version of Dang and Tassios 10 it was necessary to determine new parameters using the experimental database of this work.