RESOLUTION OF ACID STRENGTH IN TERT-BUTYL ALCOHOL AND ISOPROPYL ALCOHOL OF SUBSTITUTED BENZOIC-ACIDS, PHENOLS, AND ALIPHATIC CARBOXYLIC-ACIDS

Dissociation constants of a host of substituted benzoic acids, phenols, and some substituted acetic acids and their tetraethylammonium salts have been determined in tert-butyl alcohol, isopropyl alcohol, and some in n-hexyl alcohol. Plots of pKd (HA) in tert-butyl alcohol vs. those in water yielded slopes of 3.1 for benzoic acids, 2.1 for phenols, and only 1.2 for substituted acetic acids and diethylbarbituric acid. Corresponding values for isopropyl alcohol are 2.0, 1.4, and 1.1, as compared to 1.4, 1.1, and 1.0, respectively, for methanol. The large resolution in t-BuOH is attributed to an increase in dispersion interaction of A- with solvent upon introduction of electronegative substituents. This conclusion is substantiated by the effects of substituents on Kd of the tetraethylammonium salts and on values of transfer activity coefficients of A-between t-BuOH and methanol. © 1979, American Chemical Society. All rights reserved.