Correlation between molecular interactions and excess thermodynamic parameters of binary mixtures

Excess thermodynamic parameters, viz., internal pressures, π_i, free volumes, V_f, excess internal pressures, π_i^E, excess free volumes, V_f^E, excess free energy, G^E, excess enthalpy, H^E and entropy, S^E of mixing for the binary mixtures of 1,4-dioxane with aromatic hydrocarbons (benzene, toluene, o-xylene, m-xylene, p-xylene and mesitylene) have been evaluated from experimental ultrasonic speed and density data over the whole composition range at 298.15 K. The results are interpreted from the point of view of prevailing intermolecular interactions between unlike molecules in the mixture. Electron donor-acceptor type (or charge-transfer) interactions between 1,4-dioxane (acting as donor) and the π-electrons of ring of aromatic hydrocarbon molecules (acting as acceptor) have been observed and the magnitude of these interactions in the mixtures follow the order: benzene > toluene > p-xylene > m-xylene > o-xylene > mesitylene.