Quantitative treatment of the ortho-effect in reactions of ortho-substituted phenylmercaptoacetic acids

The kinetics of oxidation of ortho-substituted phenylmercaptoacetic acids by bromamine T and metaperiodate ion and also thepk _a values of these acids have been studied. Regression analyses of the rate and equilibrium data indicate that the ortho-substituent effect can be explained by the electrical effects alone, and that in these acids when the reaction site is in close proximity to the ortho-substituent or not, the steric effect is insignificant. The rates of oxidation and the ionization constants of these acids are largely controlled by the inductive effect.