Tritium nuclear magnetic resonance spectroscopy. Part II. Chemical shifts, referencing, and an application

Abstract

With the aid of compounds partially monotritiated by base-catalysed exchange with labelled water, corresponding triton and proton chemical shifts measured from internal tritiated water under the same conditions are shown to be the same. Applying this result and using the accurate resonance frequencies of the two nuclei measured at constant field on many of the compounds in organic solvents, a mean value, 1·06663975 (±3 × 10^–8), has been obtained for the ratio of the Larmor frequencies, ω_T/ω_H. This value enables an accurate ghost reference for any ³H n.m.r. spectrum to be derived from the observed ¹H n.m.r. frequency of the normal internal reference. The convenience of ³H n.m.r. spectroscopy for solving mechanistic problems is illustrated in respect of the Reimer–Tiemann reaction.