Kinetic and mechanistic study of the reduction of 2,6-dichlorophenol indophenol by dithionites |
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Authors: | CN Konidari MI Karayannis |
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Institution: | Department of Chemistry, University of Ioannina, Ioannina Greece |
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Abstract: | The reaction of 2,6-dichlorophenolindophenol (DCPI) and dithionites is studied kinetically by applying the stopped-flow technique. Reaction rate constants are given for the pH range 1.30–6.80. The reaction was found to follow first-order kinetics with respect to each of the reactants. For pH 3.97, 5.10 and 6.80, the second-order reaction rate constant was determined by applying four different technique. Mean values of k = 172±5, 200±2 and 276±4 l mol?1s?1 are given for pH 3.97, 5.10 and 6.80, respectively. A mechanism is proposed for the reaction, which suggests partial reactions of all possible species of DCPI and dithionites at any pH. An equation for the calculation of k at any pH is derived, which gives k as a function of H+], the partial reaction rate constants and the dissociation constants of DCPI and H2S2O4. Values of reaction rate constants of all possible partial reactions are also presented. |
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