Manganese(II) catalysed oxidation of glycerol by cerium(IV) in aqueous sulphuric acid medium: a kinetic and mechanistic study

摘要

The manganese(II) catalysed oxidation of glycerol by cerium(IV) in aqueous sulphuric acid has been studied spectrophotometrically at 25 °C and 7=1.60 mol dm~(-3). Stoichiometry analysis shows that one mole of glycerol reacts with two moles of cerium(IV) to give cer-ium(III) and glycolic aldehyde. The reaction is first order in both cerium(IV) and manganese(H), and the order with respect to glycerol concentration varies from first to zero order as the glycerol concentration increases. Increase in sulphuric acid concentration, added sulphate and bisulphate all decrease the rate. Added cerium(IH) retards the rate of reaction, whereas glycolic aldehyde had no effect. The active species of oxidant and catalyst are Ce(SO4)2 and [Mn(H2O)4]~(2+). A mechanism is proposed, and the reaction constants and activation parameters have been determined.