Investigation on Preferential Solvation, Transfer Properties and Solvent Effect of Sulfachloropyridazine in Aqueous Co-solvent Solutions of Some Alcohols

The effect of solvent on the solubility of sulfachloropyridazine was studied by making a correlation between the solubility values and solvent’s descriptors for solvent–solute and solvent–solvent interactions with the help of linear solvation energy relationships concept. From analysis of the molecular structure of sulfachloropyridazine, the variation of solubility was well explained in terms of the change in hydrogen bond basicity of mixtures when the mole fraction of methanol (or ethanol or isopropanol) increased in all aqueous binary solvent mixtures. The preferential solvation analysis of sulfachloropyridazine in the three aqueous co-solvent solutions of isopropanol, ethanol and methanol was carried out from solubility values through the method of inverse Kirkwood–Buff integrals. In water-rich compositions of the aqueous co-solvent solutions, the δx 1,3 values are negative, indicating that the sulfachloropyridazine was solvated preferentially by the solvent water. In intermediate and alcohol-rich compositions, sulfachloropyridazine was preferentially solvated by the isopropanol, ethanol or methanol. The magnitude of preferential solvation of sulfachloropyridazine is greater in isopropanol solutions than in the other two co-solvent solutions. Analysis results of the KAT-LSER and IKBI methods indicate that the solute mainly acts as a Lewis acid through its –NH 2 and > NH functionalities. In addition, the enthalpy, Gibbs energy and entropy of transfer were obtained, which demonstrated that the solubilization ability was more favorable in intermediate composition of the alcohols.