Abstract
Oxidation of 1, 8-dihydroxynaphthalene-3,6-disulphonic acid (CTA) and 1-amino-4-naphthalene sulphonic acid (ANS) by potassium peroxodisulphate leads to hydroxylation of these organic compounds. These oxidations may proceed through inner-sphere electron transfer as in case of ANS or by outer-sphere rnechanism in case of CTA. The homolytic fission of S2O82- is the rate determining step in the oxidation of CTA by S2O82-, whereas, the intrarnolecular electron transfer in the precursor compounds is the rate determining step in the mechanism of oxidation of ANS. Hydroxylation takes place in paraposition of benzene ring in CTA and ortho-position in ANS. The thermodynamics activation parameters were calculated. Rate of oxidation of both CTA and ANS in metlianol-water solvent mixtures is decreased by increasing methanol content in the medium.