Correlations involving chemical shifts of cresol + base complexes

Abstract

Solutions at different concentrations of o-, m- and p-cresol with a number of organic bases were studied by n.m.r. The chemical shifts of the hydroxyl proton resonances of 1 : 1 cresol + base complexes in carbon tetrachloride were measured. Linear correlations, at the different concentrations, were obtained between the measured chemical shift and the dissociation constant of the organic base in aqueous solution. These correlations were improved by applying corrections for the magnetic anisotropy of neighbouring groups to the chemical shifts of the hydrogen-bonded hydroxyl proton. Linear correlations between the observed chemical shifts for o-, m- and p-cresols were also found.