KINETICS AND MECHANISM OF THE HEXACYANOFERRATE(III) OXIDATION OF SUBSTITUTED ANILINES IN BASIC-MEDIA

The oxidation of aniline and several m- and p-substituted derivatives by hexacyanoferrate (III) was studied in basic media using a 20% w/w e thanol-water mixture as solvent. The stoichiometric measurements are c onsistent with a two-stage process, the first of which follows a 2:1 o xidant:reductant ratio, with azobenzenes as the main products, The rea ction is first order in both oxidant and reductant, with a negligible effect of hydroxide ion concentration; however, a decrease in rate eff ect on the overall reaction caused by the initial addition of hexacyan oferrate (II) to the reaction mixture was observed. Kinetic evidence f or a specific catalytic effect by binding of alkali-metal ions to the oxidant is reported. The effect of electron-donor substituents on the reactivity of the anilines investigated is interpreted on the basis of the Hammett equation.