Kinetic and mechanistic investigation of Allura red ac by Chloramine-t in HCL medium: A Spectrophotometric approach

Allura Red AC (ARED) is an azo dye allowed as a food additive in the European Union and other developed countries. The kinetics of oxidation of ARED with Chloramine-T in HCl medium has been studied spectrophotometrically at 302K.The reaction exhibited first-order dependence of rate on both [ARED] and [CAT], inverse fractional order dependence of rate on [HCl]. Solvent composition shows negative effect indicating the involvement of negative ion-dipolar molecule in the rate determining step. Variation of ionic strength of the medium and addition of halide ions showed negligible effect. Addition of p-toluenesulphonamide, the reduction product retards the rate. Oxidation products were isolated and characterized and were identified as 1, 2-naphthaquinone and 4-methyl anisole which are often allergic to human beings. The effect of temperature is studied at different temperatures and Activation parameters have been evaluated. Plausible mechanism and related rate law have been deduced for the observed kinetics.