Oxidation of C.I. Acid Red 27 by Chloramine-T in perchloric acid medium: Spectrophotometric, kinetic and mechanistic approaches

The kinetics of the oxidation of the azo dye C.I. Acid Red 27 (Amaranth) by sodium N-chloro-p-toluenesulfonamide (Chloramine-T, [CAT]) in HClO4 medium were studied spectrophotometrically at 293 K. The reaction rate shows first-order dependence on [CAT]0 and [dye]0 and an inverse-fractional order on [HClO4]. Activation parameters for the composite reaction and the reaction constants involved were computed. The stoichiometry of the reaction was found to be 1:1 and the oxidation products of the dye were identified as naphthalene and 1,2-naphthoquinone by GC–MS data. The observed results have been explained in terms of a mechanism and a relevant rate law has been deduced.