Linear alkanoates + aromatic hydrocarbon binary mixtures: new excess enthalpy measurements and DISQUAC analysis of thermodynamic properties

Abstract

Excess enthalpies at 298.15 K and atmospheric pressure are reported for 8 binary liquid mixtures of n-alkanoates (propyl methanoate, butyl methanoate, ethyl ethanoate, propyl ethanoate, butyl ethanoate, methyl propanoate, ethyl propanoate, propyl propanoate) + toluene. These experimental results along with literature data on vapour-liquid equilibrium (VLE), excess molar Gibbs energies (Ge), excess molar enthalpies (He), activity coefficients at infinite dilution (γi∞) and excess molar heat capacities (Cpe) of n-alkanoates + benzene, or + toluene are examined on the basis of the DISQUAC group contribution model. The components in the mixtures are characterized by three types of contact surfaces: carboxylate (COO group), aliphatic (CH3 or CH2 groups) and aromatic (C6H6 or C6H5 groups, in benzene or in toluene, respectively). Interaction parameters for aliphaticaromatic and aliphaticCOO contacts have been estimated previously. In this work, we have determined the missing heat capacity interaction parameters of the aliphaticCOO contact and all the interaction parameters of the aromaticCOO contact. The aromaticCOO contact is best described by entirely dispersive parameters. The Gibbs energy and enthalpy parameters decrease, whereas the heat capacity parameters increase, with the n-alkyl chain of the n-alkanoate.