Supramolecular structure and physicochemical properties of the dioxane-ethanol mixtures

The excess thermodynamic functions (Gibbs energy and enthalpy) and the dielectric constant of the 1,4-dioxane-ethanol solutions have been analyzed in the entire range of compositions and in a wide temperature range in the framework of the quasichemical model of non-ideal associated solution (QCNAS). The model of supramolecular structure, taking into account chain-like and cyclic aggregation of alcohol molecules and complexation of alcohol aggregates with dioxane, is able to reproduce the physicochemical properties of the mixtures with good accuracy. The equilibrium constants, Gibbs energies, enthalpies, entropies of aggregation and structural parameters of supramolecular aggregates are calculated. Distribution functions of aggregates over size and structure are reported. Supramolecular ethanol aggregates with long range molecular correlations that extend beyond the nearest coordination shells are revealed. The role of self-aggregation (both linear and cyclic) of alcohol molecules and complex formation of alcohol aggregates with dioxane in the physicochemical properties of the mixtures is discussed.