KINETICS AND MECHANISM OF OXIDATION OF ACETOPHENONE SEMICARBAZONE ANDP-METHOXYACETOPHENONE SEMICARBAZONE BY PEROXODISULFATE

Kinetics of oxidation of acetophenone semicarbazone and p-methoxyaceto phenone semicarbazone by peroxodisulphate have been studied in aqueous acetic acid medium. The reaction exhibits a first order dependence wi th respect to \PDS\. A plot of k(-1) vs \substrate\ is linear. Effects of added H+ and salt have also been investigated. The stoichiometry i s 1:1. A suitable mechanism has been proposed to account for these obs ervations. The large negative Delta S-+/- values indicate that the act ivated complexes are addition complexes of the substrate and PDS. The substituent effect on the reaction rate has been studied. A sharp comp arison is made with the corresponding reactions of the similar peroxid e SO5-.