Osmium(VIII) mediated oxidation of mercury(I) by cerium(IV) in aqueous sulphuric acid – a kinetic and mechanistic study

The oxidation of Hg^I by Ce^IV has been studied in aqueous H₂SO₄. A minute amount (10^–6 mol dm^–3) of Os^VIII is sufficient to catalyse the reaction. The active catalyst, substrate and oxidant species are H₂OsO₅, [Hg₂(SO₄)HSO₄]^– and H₃Ce(SO₄)^– ₄, respectively. Possible mechanisms are proposed and the reaction constants involved have been determined.     

Kinetics and mechanism of palladium(II) catalyzed chromium(VI) oxidation of mercury(I) in aqueous sulphuric acid

The Cr^VI oxidation of Hg^I in an aqueous acid medium occurs to a modest extent only in presence of Pd^II and in H₂SO₄ above ca. 0.20 mol dm^–3. The reaction is first order in [Cr^VI] in the presence of Pd^II catalyst. The order in [Hg^I] is less than unity, whereas that in [Pd^II] is unity. Increase in [H₂SO₄] accelerates the reaction rate. The added products, Cr^III and Hg^II, do not significantly effect the reaction rate. A mechanism involving HCrO₄ ^– and PdCl⁺ as the reactive species of oxidant and catalyst respectively, is proposed. The reaction constants involved in the mechanism have been evaluated.     

A kinetic and mechanistic study of thallium(I) oxidation by quinolinium dichromate (QDC), a new oxidant

Quinolinium dichromate (QDC) oxidation of Tl^I in aqueous AcOH containing large concentrations of HCl is considerably accelerated both by H⁺ and Cl^– ions as well as by increasing the AcOH concentration in the medium; oxidation is made possible by altering the redox potentials. The reaction is first order in oxidant and in reductant but apparently less than unit order in [Cl^–] and nearly second order in [H⁺]. The active species of QDC and Tl^I are ClCrO₃ ^– and TlCl₂ ^– respectively. A possible mechanism is proposed and verified, and the reaction constants involved have been evaluated.     

Oxidation of palladium(II) by hexacyanoferrate(III) in aqueous ethanoic acid: a mechanistic study

The oxidation of Pd^II by Fe(CN) ₆ ^3– has been studied in 55% MeCO₂H–H₂O containing 4.0 mol dm^–3 HCl, the oxidation being made possible by altering redox potentials. The active species of Pd^II and Fe(CN) ₆ ^3– are PdCl ₃ ^– and H₂Fe(CN) ₆ ^– , respectively. A possible mechanism is proposed and verified, and the reaction constants involved have been evaluated.