Solvation of dibenzo-18-crown-6 ether in water-aprotic solvents

The Gibbs free energies of transfer of dibenzo-18-crown-6 ether from dimethyl sulfoxide and N,N-dimethylformamide to their mixtures with water (ΔtrG0(DB18C6)solv→χW) were determined by the interphase distribution method. The enthalpies of dissolution of DB18C6 were determined by the calorimetric method at 25.00 ± 0.01 °C. The analysis of the influence of solvent composition and properties on the thermodynamic characteristics of DB18C6 solvation was carried out. It was found that a change in the solvent composition in both cases does not lead to significant changes in the crown ether solvation state. A compensation effect in enthalpy and entropy contributions to ΔtrG0(DB18C6) was observed. It has been shown that the priority contribution to the change in the thermodynamic characteristics of DB18C6 solvation is made by the resolvation of the crown ring oxygen atoms. The resolvation of DB18C6 occurs at χW > 0.6 mol fr. Proper data are compared with data reported in the literature.