A Study of the Nucleophilic Solvation Based on the Theory of Chemical Equilibrium

Abstract

Abstract The nucleophilic solvation to a deuterium atom in a methanol-d molecule has been quantitatively studied by using the infrared spectroscopic data of the O–D vibrational band. The position of the O–D band did not change in spite of the variation in the methanol-d concentration in solutions of a single solvent, whereas the area of the O–D peak changed in proportion to the first-order of the methanol-d concentration. From these results, it has been concluded that the area of the O–D band corresponds to the concentration of the methanol-d solvated. In a binary solvent system, which consisted of components with substantial differences in the electron-donating power, two positions of the O–D peak were observed at positions identical to those in the component examined in a single solvent system, and the area of each O–D peak changed with the composition of the system. These results led to the conclusion that the nucleophilic solvation of each component in the binary system took place competitively and individually. From the quantitative treatment of the results on the basis of the theory of chemical equilibrium, the equilibrium constant of the nucleophilic solvation of a solvent to methanol-d was calculated. The following empirical formula was obtained between the electron-donating powers and the nucleophilic equilibrium constants of various solvents: (Remark: Graphics omitted.)