- Kinetics and mechanism of ruthenium (III) - Catalysed oxidation of pyrimidine bases by peroxydiphosphate in aqueous perchloric acid medium
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Kinetics and mechanism of Ru(III) - catalysed oxidation of pyrimidine bases by peroxydiphosphate (PDP) have been studied in aqueous perchloric acid medium. The reaction is first order each in [PDP] and [Ru(III)] and the rate is independent of [substrate]. The reaction is insensitive towards changes in acid concentration while the effect of ionic strength is negligible on the rate of oxidation. The reactions have been studied at different temperatures and activation parameters evaluated. A mechanism, involving the two-electron oxidation of Ru(III) by PDP in a slow step, is proposed.
- Suvarna Latha,Adinarayana,Jayaprakash Rao
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p. 1184 - 1187
(2007/10/03)
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- Kinetics and mechanism of oxidation of pyrimidine nucleobases by diperiodato- Argentate(III) in aqueous alkaline medium
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The kinetics of oxidation of pyrimidine nucleobases, viz., uracil, thymine, 5-bromouracil, 6-methyluracil and cytosine by diperiodatoargentate(III) (DPA) in aqueous alkaline medium have been studied. The reaction is first order both with respect to [DPA] and [pyrimidine base]. The oxidation rate increases with increase in [OH-] and decreases with increase in added [periodate]. The reaction rate is not affected by varying the ionic strength. The stoichiometry of the reactions is 1:1 and the product of oxidation under kinetic conditions has been found to be the corresponding 5, 6-dihydroxy-5, 6-dihydropyrimidine. The reactions have been studied in the temperature range 278-303 K and the activation parameters calculated. It is assumed that the metal entity, i.e., Ag(III) is initially involved in η2-binding to the C(5)-C(6) double bond of the pyrimidine in a slow step. The Ag(III)-pyrimidine complex thus formed dissociates in a subsequent fast step to give the products. The order of reactivity of the pyrimidines has been found to be: cytosine>uracil>5-bromouracil~6-methyluracil>thymine and the reasons for the observed order discussed.
- Krishna, Kondamudi Venkata,Jaya Prakash Rao
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p. 1106 - 1110
(2007/10/03)
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