Solvation spectra. Part 28.—N.m.r. studies of aqueous tertiary butyl alcohol in the presence and absence of various solutes

Abstract

Changes in water structure caused by the addition of up to 0.18 mole fraction tertiary butyl alcohol (TBA) have been investigated by following shifts in the n.m.r. resonances of both water and TBA protons, and also of certain nuclei in selected compounds added in small amounts to act as probes. The results may be divided into two groups depending on whether the nuclei undergoing resonance are directly involved in hydrogen-bonding with water protons or not. The first group shows strongly increasing hydrogen-bonding in the TBA mole fraction x₂ region 0–0.05. This effect is greatly enhanced on cooling. The second group, comprising species not directly involved in solvent-solute hydrogen-bonding, is sensitive to changes in solvent only when x₂ > 0.05. These results are explained in terms of a clathrate model previously invoked for this solvent system.