Thermodynamic Study of Binary Mixtures Containing an Isobutylalkanol and an Alkyl (Ethyl to Butyl) Alkanoate (Methanoate to Butanoate), Contributing with Experimental Values of Excess Molar Enthalpies and Volumes, and Isobaric Vapor−Liquid Equilibria

This paper reports measurements on vapor−liquid equilibria and other mixing thermodynamic properties, and, for 12 binary mixtures formed by 12 aliphatic esters (from methanoate to butanoate) and 2-methylpropan-1-ol. To complete the study another set of data published previously containing methyl alkanoates (ethanoate to butanoate) with the same isobutylalkanol is also incorporated into the interpretation of the behavior of these mixtures. All equilibrium data were found to be consistent using a version of a point-to-point test, and for the data correlation a new equation containing temperature-dependent parameters was used to relate the equilibrium quantities and excess enthalpies; the results were acceptable. To observe the regularity of results obtained, a matrix for the more relevant quantities for the vapor−liquid equilibrium is presented. For the set of 15 mixtures considered in this study, only five presented azeotropes, namely, isobutylalkanol + methyl butanoate, + ethyl propanoate, + propyl ethanoate, + propyl propanoate, and + butyl methanoate. The ASOG and modified-UNIFAC models estimate well the activity coefficients for the mixtures considered in this study; however, this last model, using the same set of interaction parameters, predicts fairly well the excess enthalpies of all mixtures with differences ranging from 12 to 26%.