KINETICS OF HEXACYANOFERRATE(III)-CATALYZED PERBORATE OXIDATION OF SOME PARA-SUBSTITUTED, META-SUBSTITUTED AND ORTHO-SUBSTITUTED ANILINES

The rates of hexacyanoferrate(III) - catalyzed perborate oxidation of 25 para-, meta- and ortho-substituted anilines at 40-55 degrees C, in aqueous acetic acid-ethylene glycol medium, afford enthalpy and entrop y of activation. The isokinetic and Exner relationships hold. The effe ct of para substituents on the oxidation rate is governed by sigma(1) (44%) and sigma(R)(-) (56%) whereas the meta-substituents conform to S wain et al. F (64%) and R (36%), both with negative reaction constants . In the oxidation of ortho-substituted anilines field, resonance and steric effects operate by 60, 18 and 22%, respectively. The specific r ate of oxidizing species - para-substituted anilines reaction (k(2)), calculated using the pK(a) and pH, correlates with sigma(-) (rho(-)=-2 .7) and k(2) of meta-substituents is governed by sigma(1) (73%) and si gma(R)(+) (27%) with negative reaction constants. The operation of loc alized, delocalized and steric effects on k(2) of ortho-substituted an ilines are 70, 21 and 9%, respectively, and the ortho-nitro and ortho- carboxylic groups prefer orthogonal orientation.