The supramolecular structure and physicochemical properties of 1,4-dioxane-methanol and 1,4-dioxane-ethanol solutions

The quasi-chemical model of nonideal associated solutions was used to analyze the excess thermodynamic functions (Gibbs energy, enthalpy, and entropy) and permittivity of 1,4-dioxane-methanol and 1.4-dioxane-ethanol solutions. A model of supramolecular organization was suggested and substantiated. This model took into account chain and cyclic association of alcohol molecules with the formation of H-O...H-O-type H-bonds and complex formation between alcohols (monomers and chain associates) and dioxane with the formation of C2O...H-O H-bonds. The equilibrium constants and the integral and differential characteristics of supramolecular aggregation were determined. The presence of long-range correlations of molecules and the collective character of H-bonds were established. The excess Gibbs energy of solutions was determined by commensurate contributions of specific, dipole, and dispersion interactions. Aggregation processes made a negative contribution to the excess Gibbs energy and positive contributions to the excess enthalpy and entropy. Positive deviations of the dipole correlation factor from one were caused by the predominance of alcohol chain associates and alcohol complexes with dioxane. Chain associates and complexes had the strongest effect on the structure and properties of dioxane-alcohol solutions, whereas the role played by cyclic associates was insignificant.