The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16\^6—40 ℃). The first order rates with res...The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16\^6—40 ℃). The first order rates with respect to glycol and Ag(Ⅲ) were all found. The rates increased with the increase in [OH -] and decreased with the increase in [TeO 2- 4]. No effect was found with the addition of KNO 3 and no free radical was detected. In view of this, the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species. A plausible mechanism involving a two electron transfer is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate determining step and constants are evaluated.展开更多
The kinetics of oxidation of glycol by dihydroxydiperiodato nickelate ( Ⅳ) complex (DDN) was studied by spectrophotometry in aqueous alkaline medium in a temperature range of 25-40℃. The reaction was found to be fir...The kinetics of oxidation of glycol by dihydroxydiperiodato nickelate ( Ⅳ) complex (DDN) was studied by spectrophotometry in aqueous alkaline medium in a temperature range of 25-40℃. The reaction was found to be first order with respect to Ni( Ⅳ ) and also to be first order with respect to glycol. The rate increases with the increase in [OH ] and decreases with the increase in [IO-4], showing that dihydroxymonoperiodatonickelate ( Ⅳ )(DMN) is the reactive species of oxidant. Salt effect indicated that the reaction is of ion-dipole type. No free radical was detected. A mechanism of an inner-sphere two-electron transfer reaction involving a preequilibrium between DDN and DMN is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate-determing step and the equilibrium constants were calculated.展开更多
The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ)[abbreviated as DDA of Ag(Ⅲ)] anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature ...The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ)[abbreviated as DDA of Ag(Ⅲ)] anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature range of 25- 40 ℃ . The order of the redox reaction of lactic acid and DDA was found to be first order. The rates increased with the increase in and decreased with the increase in . No free radical was detected. In the view of this the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species. A plausible mechanism involving a two electron transfer is proposed, and the rate \{equation\} derived from the mechanism can be used to explain all the experimental results. The activation parameters(25 ℃) and the rate constants of the rate determining step along with the preequilibrium constants at different temperatures were evaluated.展开更多
The kinetics of oxidation of ethylene glycol monoethylether (EGE) by diperiodatonickelate(IV) ion (DPN) was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependence on Ni(IV) an...The kinetics of oxidation of ethylene glycol monoethylether (EGE) by diperiodatonickelate(IV) ion (DPN) was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependence on Ni(IV) and positive fractional order with respect to EGE. The pseudo-first order rate constants,kobs increased with the increase of and decreased with the increase of . Added salts had little effect on the rate and no free radical was detected. Based on these,the mechanism including the equilibrium between DPN and EGE was proposed. Furthermore,the activation parameters of the reaction were calculated.展开更多
The kinetics of oxidation of potassium thiocyanate by diperiodatoargentate （Ⅲ） （DPA） ions was studied in aqueous alkaline medium ([OH<sup>-</sup>]=7.00×10<sup>-3</sup>—0.200 mol. dm&...The kinetics of oxidation of potassium thiocyanate by diperiodatoargentate （Ⅲ） （DPA） ions was studied in aqueous alkaline medium ([OH<sup>-</sup>]=7.00×10<sup>-3</sup>—0.200 mol. dm<sup>-3</sup>) at a constant ionic strength (μ=0.30 mol. dm<sup>-3</sup>). It is found that the reaction order in DPA is unity. The dependence of the rate on [OH<sup>-</sup>] implies that there are two pathways through which the reaction proceeds. In each pathway, the order in NCS-is fractional and the kinetic data fit well in with Michaelis-Menten process. The influence of ligand on the reaction is examined and the reactive species are inferred. Two pathways of inner-sphere two-electrons transfer are believed to be involved in the oxidation. The rate equations are derived and all the equilibrium constants and rate constants are evaluated. Activation parameters of one pathway are determined.展开更多
The kineties and mechanism of oxidation of α-alanine by diperiodatocuprate (Ⅲ) ion was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependance in oxidant and 1.25 order depen...The kineties and mechanism of oxidation of α-alanine by diperiodatocuprate (Ⅲ) ion was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependance in oxidant and 1.25 order dependance in α-alamne. It was found that the pesudo first-order ([Ala].》 [Cu(Ⅲ)].) rate constant kobs increases with the increases in [OH] and decreases with the increases in [IO]. The hnear relationships between [Ala/kobs and 1/[Ala] and between 1/kobs and [IO] were observed in our experiment. There is a positive salt effect. Under the protection of nitrogen gas, the reaction system can induce polyn1erzation of acrylamide. A plausible mechanism involving free redicals has been proposed. The rate equations derived from the mechanism explained all the experimental results satisfactorily. The rate constant activation paIameters of rate determing step have been calculated.展开更多
基金Supported by the Natural Science Foundation of Hebei Province(No.2 95 0 6 6 )
文摘The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16\^6—40 ℃). The first order rates with respect to glycol and Ag(Ⅲ) were all found. The rates increased with the increase in [OH -] and decreased with the increase in [TeO 2- 4]. No effect was found with the addition of KNO 3 and no free radical was detected. In view of this, the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species. A plausible mechanism involving a two electron transfer is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate determining step and constants are evaluated.
文摘The kinetics of oxidation of glycol by dihydroxydiperiodato nickelate ( Ⅳ) complex (DDN) was studied by spectrophotometry in aqueous alkaline medium in a temperature range of 25-40℃. The reaction was found to be first order with respect to Ni( Ⅳ ) and also to be first order with respect to glycol. The rate increases with the increase in [OH ] and decreases with the increase in [IO-4], showing that dihydroxymonoperiodatonickelate ( Ⅳ )(DMN) is the reactive species of oxidant. Salt effect indicated that the reaction is of ion-dipole type. No free radical was detected. A mechanism of an inner-sphere two-electron transfer reaction involving a preequilibrium between DDN and DMN is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate-determing step and the equilibrium constants were calculated.
基金Supported by the National Natural Science Foundation of Hebei Province(No.2 95 0 6 6 )
文摘The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ)[abbreviated as DDA of Ag(Ⅲ)] anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature range of 25- 40 ℃ . The order of the redox reaction of lactic acid and DDA was found to be first order. The rates increased with the increase in and decreased with the increase in . No free radical was detected. In the view of this the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species. A plausible mechanism involving a two electron transfer is proposed, and the rate \{equation\} derived from the mechanism can be used to explain all the experimental results. The activation parameters(25 ℃) and the rate constants of the rate determining step along with the preequilibrium constants at different temperatures were evaluated.
文摘The kinetics of oxidation of ethylene glycol monoethylether (EGE) by diperiodatonickelate(IV) ion (DPN) was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependence on Ni(IV) and positive fractional order with respect to EGE. The pseudo-first order rate constants,kobs increased with the increase of and decreased with the increase of . Added salts had little effect on the rate and no free radical was detected. Based on these,the mechanism including the equilibrium between DPN and EGE was proposed. Furthermore,the activation parameters of the reaction were calculated.
文摘The kinetics of oxidation of potassium thiocyanate by diperiodatoargentate （Ⅲ） （DPA） ions was studied in aqueous alkaline medium ([OH<sup>-</sup>]=7.00×10<sup>-3</sup>—0.200 mol. dm<sup>-3</sup>) at a constant ionic strength (μ=0.30 mol. dm<sup>-3</sup>). It is found that the reaction order in DPA is unity. The dependence of the rate on [OH<sup>-</sup>] implies that there are two pathways through which the reaction proceeds. In each pathway, the order in NCS-is fractional and the kinetic data fit well in with Michaelis-Menten process. The influence of ligand on the reaction is examined and the reactive species are inferred. Two pathways of inner-sphere two-electrons transfer are believed to be involved in the oxidation. The rate equations are derived and all the equilibrium constants and rate constants are evaluated. Activation parameters of one pathway are determined.
文摘The kineties and mechanism of oxidation of α-alanine by diperiodatocuprate (Ⅲ) ion was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependance in oxidant and 1.25 order dependance in α-alamne. It was found that the pesudo first-order ([Ala].》 [Cu(Ⅲ)].) rate constant kobs increases with the increases in [OH] and decreases with the increases in [IO]. The hnear relationships between [Ala/kobs and 1/[Ala] and between 1/kobs and [IO] were observed in our experiment. There is a positive salt effect. Under the protection of nitrogen gas, the reaction system can induce polyn1erzation of acrylamide. A plausible mechanism involving free redicals has been proposed. The rate equations derived from the mechanism explained all the experimental results satisfactorily. The rate constant activation paIameters of rate determing step have been calculated.
