Investigation utilizing the 18O isotope shift in 13C nuclear magnetic resonance spectroscopy. 3. Observation of a solvent dependence for tert-butyl alcohol 1

Abstract

Solvent effects on the magnitude of the 18O isotope shift in 13C NMR for the carbon bonded to the hydroxyl group in tert-butyl alcohol were investigated using an array of deuterated solvents and a more accurate measurement of the isotope shift at natural abundance 13C. For the first time, a solvent effect on the magnitude of the isotope shift was detected, which was smallest in pyridine, and increased in the following order: pyridine < acetone/p-dioxane < nitromethane < benzene < water. These results indicate that assignments of carbon signals based on the magnitude of isotope shifts must take into account the possibility of a solvent effect.