Abstract
The pH and concentration dependencies of proton and oxygen exchanges in water-solvent systems have been examined by oxygen-17 nuclear magnetic resonance (17O-NMR) spectroscopy. A pH shift in a water-acetone system results in a coalescence of the 17O water signal and an alteration in the intensities of the signals of water and acetone. The signal coalescence arises from proton exchange between water molecules and the signal alteration from oxygen exchange between water and solvent. On the other hand, dilution with solvent results in various patterns of 17O water signals from singlet to triplet. Each water-solvent sample under diluted conditions gives a specific shape which reflects the intrinsic nature of the solvent. In this case, the proton exchange can be discussed by assuming a simplified reaction mechanism. [chemical formula] It is concluded that the Fi factor, which refers to a contribution arising from water-solvent interaction, can be taken as a good measure of proton exchange in water-solvent systems and is available for the characterization of solvents soluble in water.
