Solvation State and Selective Solvation of D-Sorbitol in Water-Dimethylformamide Medium of Varying Composition

Abstract

The solvation state of D-sorbitol has been determined in water-dimethylformamide (DMF) system (from 0 to 10 m.p.) using the method of polarimetry. The composition and formation constants of D-sorbitol – water – DMF heterosolvates have been obtained. The molar parts of D-sorbitol in heterosolvates have been found. It has been revealed that DMF acts as a selective solvent when its content is minimum (not higher than 0.7 m.p.), which is consistent with its higher nucleophilicity compared to water. If DMF concentration is higher than 0.7 m.p., there is inversion in solvation selectivity with water becoming a selective solvent. Under the experimental conditions, 12 water molecules in hydration shells were substituted with 6 DMF molecules. The substitution sequence of water molecules has been suggested