Supramolecular structure and physicochemical properties of the trichloromethane–methanol mixtures

Abstract

The excess thermodynamic functions (Gibbs energy, enthalpy, and entropy) and the dielectric permittivity of the trichloromethane–methanol solutions have been analyzed and described in the entire range of compositions and in a wide temperature range in the framework of the quasichemical model of nonideal associated solution (QCNAS). The model of supramolecular structure, taking into account the chain-like and cyclic association of alcohol molecules and complexation of alcohol aggregates with trichloromethane, is able to reproduce the physicochemical properties of the mixtures with good accuracy. The equilibrium constants, enthalpies, and entropies of aggregation, and structural parameters of supramolecular aggregates have been determined. Distribution functions of aggregates over size and structure have been calculated. Supramolecular methanol aggregates with long-range molecular correlations have been revealed. Specific interactions are shown to give the main contribution to the positive deviations from the ideal solution behavior. Positive deviation of the dipole correlation factor from unity is due to a predominantly parallel orientation of the dipoles in the methanol aggregates and in the complexes with trichloromethane. The influence of methanol association (linear and cyclic) as well as solvation on the physicochemical properties of the mixtures is discussed.