NMR Conformational analysis of 4-hydroxycyclohexanone and 1,4-cyclohexanediols. Coupling constants averaging induced by conformational equilibria and by strong coupling effects—role of solvent

Significant differences are observed in the NMR spectra of cis-1,4-cyclohexanediol and 4-hydroxycyclohexanone measured in different solvents. For the diol the differences are shown to arise from averaging of coupling constants through strong coupling effects. The differences for the ketone result from a combination of the same factors plus differences in conformational equilibria. A discussion of the averaging of coupling constants due to conformational equilibria and due to strong coupling effects is given. The signal band width method for determination of conformational equilibria is shown to be independent of strong coupling effects.