P.G. Department of Chemistry, Utkal University, Bhubaneswar-751 004, Orissa, India biMMT, Bhubaneswar, Orissa, India P.G. Department of Chemistry, Khallikote (Autonomous) College, Berhampur-760 001, Orissa, India E-mail : ajaypattanaik_kumar@yahoo.co.in P.G. Department of Chemistry, Ravenshaw University, Cuttack-753 003, Orissa, India Manuscript received 25 November 2010. revised 09 March 2011, accepted 17 March 2011 The kinetics of the redox reaction of MCC (morpholinium chlorochromate) with

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... cysteine and DL-methionine have been studied over the range 2.0 ≤ 103 [amino acid]T ≤ 6.0, 0.1 ≤ [H+] ≤ 0.25, 0.1 ≤ I ≤ 0.8 mol dm-3 and 293 K ≤ T ≤ 313 K in aqueous perchlorate medium. The redox reaction showed first order dependence in [amino acid] r and [MCC]T. The main products of the reaction were cystine and methionine sulfoxide respectively. The activation parameters ΔH# (kJ moi-1) and ΔS1 (JK-1 moi-1) for the redox reactions of L-cysteine and DL-methionine for k1 and k2 paths are found to be 44.82 ± 9.1, 54.11 ± 7.1, 26.69 ± 9.0, 60.64 ± 12.24 and -243.05 ± 29.8, -268.29 ± 23.4 and -206.62 ± 30.3, -319.83 ± 40.43 respectively. The valus of ΔH# and ΔS# were both favourable for electron transfer processes. Negative ΔS# indicates the ordered transition state for the redox reactions.