• J Viroopakshappa

      Articles written in Journal of Chemical Sciences

    • Kinetics and mechanism of oxidation of dimethyl sulphoxide by sodium bromate-sodium bisulphite reagent in aqueous medium

      J Viroopakshappa V Jagannadham

      More Details Abstract Fulltext PDF

      Rates of oxidation of dimethyl sulphoxide (DMSO) by HOBr producedin situ from sodium bromate-sodium bisulphite reagent have been studied iodometrically in aqueous medium. The order in [DMSO] is one when [DMSO] < 001 mol dm-3, fractional when [DMSO] is between 0.01 and 0.5mol dm-3 and zero when (DMSO) > 0.5 mol dm-3. Different rate laws are operative under these three conditions though HOBr is the effective oxidizing species in all the cases. A mechanism involving an intermediate four-membered cyclic transition state between DMSO and HOBr (formation constantK), which decomposes in a slow step with a rate constant(k) has been proposed. Thermodynamic parameters for the adduct formation step and activation parameters for the first-order decomposition of the adduct step have been evaluated in the temperature range 308–323 K. Activation parameters have also been determined while the orders in [DMSO] are unity and zero. The reaction product has been identified as dimethyl sulphone (DMSO2).

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