LINEAR ALKANOATES PLUS AROMATIC HYDROCARBON BINARY-MIXTURES - NEW EXCESS ENTHALPY MEASUREMENTS AND DISQUAC ANALYSIS OF THERMODYNAMIC PROPERTIES

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 (G(E)), excess molar enthalpies (H-E), activity coefficients at infinite dilution (gamma(i)(infinity) and excess molar heat capacities (Cp(E)) 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 aliphatic/aromatic and aliphatic/COO contacts have been estimated previously. In this work, we have determined the missing heat capacity interaction parameters of the aliphatic/COO contact and all the interaction parameters of the aromatic/COO contact. The aromatic/COO contact is best described by entirely dispersive parameters. The Gibbs energy and enthalpy parameters decrease, whereas the heat capacity parameters increase, with the n-allcyl chain of the n-alkanoate.