Solvation of NaC1 in Water-l-Propanol Mixtures

Abstract

The proton chemical shifts of solvent molecules were measured for dissolving or not dissolving NaC1 in water-1-prcipanol mixtures at 32°C. Only one peak was observed as 'H-NMR spectrum for both water protons and 1-propanol hydroxyl protons in the mixed solvents which contained less than 85% of alcohol in mass fraction. In mixed solvents without NaC1, a slight shift of this average peak to the low field was observed when the concentration of 1-propanol was from 0% to about 10%. But this peak gradually shifted to the high field above about 10%. It was inferred from these results that the addition of a small amount of 1-propanol to water enhanced the solvens structure by the formation of hydrogn bonds. When NaC1 was dissolved in a mixed solvent, the proton sign als for solvent molecules shifted straightforwardly to the high field with the increase of NaC1concentration. From these results and structual changes in mixed solvents, it was inferred that water molecules preferentially solvated to ions at lower concentration of 1-propanol but molecules of both water and alcohol solvated at its higher concentration.