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 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 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
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 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 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.
