18O isotope shift upon 13C NMR spectra and its application to the study of oxygen exchange kinetics

The natural abundance 13C NMR spectra of C-1 of tert-butyl alcohol were measured from known concentrations of [18O]- and [16O]-tert butyl alcohol in water-deuterium oxide. An upfield shift occurs because of 18O isotopic substitution at the hydroxyl carbon. The acid-catalyzed exchange of the hydroxyl oxygen of tert-butyl alcohol was measured by 13C isotope shift NMR. 18O-labelled tert-butyl alcohol was dissolved in .16 N hydrochloric acid. The loss of 18O from the C-1 position of the alcohol was measured as a function of time. By 810 m no further change was measureable. The 13C spectra were recorded on a Varian CFT-20 spectrometer at 650C. 2 figures