The Influence of Aqueous-Ethanol Solvent on the Acid-Base and Complexation Properties of 1-Ethyl-2h-Imidazoline-2-Thione

Systematization of the obtained experimental results revealed that, upon transfer of 1-ethyl-2H-imidazoline-2-thione from water to an aqueous–ethanol medium, the dependence of ΔG on the mole fraction of ethanol (χ CHOH) exhibits an extremum at an ethanol mole fraction of 0.1. This indicates that the maximum weakening of solvation of the studied compound is observed at this concentration. Further increase in ethanol content in the binary solvent leads to a decrease in ΔG. For 1-ethyl-2H-imidazoline-2-thione, the dependence of pK = f(χ EtOH, mole fraction) is also extremal and shows a minimum in the region of 0.1 mole fraction of ethanol. Overall, the basicity of 1-ethyl-2H-imidazoline-2-thione changes only slightly upon transition from water to the aqueous–ethanol solvent. Analysis of the solvation contributions of the initial substances in the formation of the monosubstituted complex showed that the stability of the [Ag(1-EI)] complex is largely determined by changes in the solvation environment of the complex species. At the same time, the contribution of the difference in the thermodynamic transfer functions of the ions {ΔG - ΔG} to the overall effect is insignificant.