The kinetics of oxidation of vanillin (VAN) by diperiodatoargentate (III) (DPA) in alkaline medium at a constant ionic strength of 1.0 mol dm -3 was studied spectrophotometrically. The reaction between DPA and vanillin in alkaline medium exhibits 1:1 stoichiometry (vanillin:DPA). The reaction is first order in [DPA] and has less than unit order both in [VAN] and [alkali]. A decrease in the dielectric constant of the medium increases the reaction rate. An increase in periodate concentration has no effect on the rate. The oxidation reaction in alkaline medium has been shown to proceed via a DPA-vanillin complex, which decomposes slowly in a rate-determining step to give the products. The main products were identified by spot test, IR, and MS studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined.

The kinetics of oxidation of L-lysine by diperiodatoargentate(III) (DPA) in aqueous alkaline medium at a constant ionic strength of 0.50 mol dm -3 was studied spectrophotometrically. The oxidation products are aldehyde, 5-aminopentanal and Ag(I). The main products were identified by spot test, IR and GC-MS. The stoichiometry is [L-lysine]:[DPA] = 1:1. The reaction is first order with respect to diperiodatoargentate(III) concentrations, whereas the order with respect to L-lysine and alkali concentrations changes from first order to zero order as the L-lysine and alkali concentrations are increased. The effects of added products, periodate, ionic strength, and dielectric constant of the reaction medium were investigated. Based on the experimental results, a mechanism involving complex formation between DPA species and L-lysine is proposed. The reaction constants involved in the mechanism were evaluated. The activation parameters with respect to the slow step of the mechanism were determined and discussed.

No abstract

No abstract

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