Substrate Inhibition in Ru(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate - Kinetic Study

What is it about?

Ruthenium(III) catalyzed oxidation of propane-1,3-diol by potassium periodate was studied in aqueous perchloric acid medium. Orders of reaction with respect to concentrations of oxidant, substrate, acid and catalyst were determined. First order in oxidant and catalyst concentrations, and inverse fractional order in acid medium were observed. In addition, substrate inhibition (i.e. a decrease in reaction rate with an increase in substrate concentration) was observed. Effect of addition of salt and solvent was studied. Based on the studies of temperature variation, Arrhenius parameters were calculated. Plausible mechanism was also proposed based on observed kinetics.

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Why is it important?

The observed substrate inhibition in the ruthenium(III) catalyzed periodate oxidation of propane-1,3-diol was explained based on the competitive formation of a complex between propane-1,3-diol and periodate. Based on the inverse acid dependence and solvent effect, H5IO6, H4IO6 − and IO4 − were the active periodate species. Formation of 3-hydroxy propanal as the final product indicates the attacking of single hydroxy group, whereas the other hydroxyl group of substrate remain intact.

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