Robert Schaal

Utilisation des correlations de hammett a l'etude des equilibres tautomeres

The acidity constants for various substituted benzoic acids and anilinium cations have been measured potentiometrically in aqueous dimethylsulphoxide media at 20°. The values obtained (pKXS) are compared with the corresponding values for aqueous media (pKXE). The linearity of the pKXS =f(pKXE) plots makes it possible to arrange in the same homogeneous series those compounds for which the substituent X causes a change in acidity verifying the classic Hammett relationship. This type of correlation is utilized to study the tautomeric zwitterion equilibrium of m-amino-benzoic acid.

The effects of solvation upon the acidities of nitroaromatics

Specific solvation of nitrated phenoxide, anilide and benzyl anions is shown to decrease in that order, with concomitant increases in substituent salvation assisted resonance effects — the nitrobenzyl anions are suggested to be essentially charge-delocalized.