The 1H chemical shifts of 124 compounds containing a variety of functional groups have been recorded in CDCl3 and DMSO-d6 (henceforth DMSO) solvents. The 1H solvent shift Delta delta = delta(DMSO) - delta(CDCl3) varies from -0.3 to +4.6 ppm. This solvent shift can be accurately predicted (rms error 0.05 ppm) using the charge model of alpha, beta, gamma and long-range contributions. The labile protons of alcohols, acids, amines and amides give both, the largest solvent shifts and the largest errors. The contributions for the various groups are tabulated and it is shown that for H.C.C.X gamma-effects (X = OH, NH, =O, NH.CO) there is a dihedral angle dependence of the gamma-effect. The group contributions are discussed in terms of the possible solvent-solute interactions. For protic hydrogens, hydrogen bonding is the dominant interaction, but for the remaining protons solvent anisotropy and electric field effects appear to be the major factors.

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It is shown that the difference in the 1H NMR chemical shift of a protic hydrogen in DMSO and CDCl3 solvents is directly related to the overall, or summation, hydrogen bond acidity for a wide range of solutes. This provides a new and direct method of measuring the hydrogen bond acidity. For 54 compounds, the observed shifts for 72 protic hydrogens could be correlated to the Abraham solute hydrogen bond acidity parameter, A, with a correlation coefficient squared, R2, of 0.938 and a standard deviation, SD, of 0.054 units in A. A training equation that used half the data could predict A values for the remaining data with an average error of 0.001 and a standard deviation, SD, of 0.053 units, thus demonstrating the predictive power of the method. Unlike any previous method for the determination of solute hydrogen bond acidities, the NMR method allows the determination of A values for individual protic hydrogens in multifunctional solutes.

The (1)H NMR spectra of a number of alcohols, diols and inositols are reported and assigned in CDCl(3), D(2)O and DMSO-d(6) (henceforth DMSO) solutions. These data were used to investigate the effects of the OH group on the (1)H chemical shifts in these molecules and also the effect of changing the solvent. Inspection of the (1)H chemical shifts of those alcohols which were soluble in both CDCl(3) and D(2)O shows that there is no difference in the chemical shifts in the two solvents, provided that the molecules exist in the same conformation in the two solvents. In contrast, DMSO gives rise to significant and specific solvation shifts. The (1)H chemical shifts of these compounds in the three solvents were analysed using the CHARGE model. This model incorporates the electric field, magnetic anisotropy and steric effects of the functional group for long-range protons together with functions for the calculation of the two- and three-bond effects. The long-range effect of the OH group was quantitatively explained without the inclusion of either the C--O bond anisotropy or the C--OH electric field. Differential beta and gamma effects for the 1,2-diol group needed to be included to obtain accurate chemical shift predictions. For DMSO solution the differential solvent shifts were calculated in CHARGE on the basis of a similar model, incorporating two-bond, three-bond and long-range effects. The analyses of the (1)H spectra of the inositols and their derivatives in D(2)O and DMSO solution also gave the ring (1)H,(1)H coupling constants and for DMSO solution the CH--OH couplings and OH chemical shifts. The (1)H,(1)H coupling constants were calculated in the CHARGE program by an extension of the cos(2)phi equation to include the orientation effects of electronegative atoms and the CH--OH couplings by a simple cos(2)phi equation. Comparison of the observed and calculated couplings confirmed the proposed conformations of myo-inositol, chiro-inositol, quebrachitol and allo-inositol. The OH chemical shifts were also calculated in the CHARGE program. Comparison of the observed and calculated OH chemical shifts and CH.OH couplings suggested the existence of intramolecular hydrogen bonding in a myo-inositol derivative.