J. R. Raju

OXIDATION OF CHROMIUM(III) BY ALKALINE HEXACYANOFERRATE(III)

SummaryAlkaline hexacyanoferrate(III) oxidation of freshly prepared solutions of CrIII (pH>12) at 27°C follows the rate law, Equation 1:1

OSMIUM(VIII) OXIDATION OF ARSENIC(III) IN AQUEOUS SULPHURIC ACID

Rate = \frac{{kK_{OH} [Fe(CN)_6 ]^{3 - } [Cr^{III} ]_T [OH^ - ]_T }}{{(1 + K_{OH} [OH^ - ]_T )}}

Chromium(III)-catalysed cerium(IV) oxidation of arsenic(III) in aqueous sulphuric acid

[Fe(CN)6]3− and [Cr(OH)4]− are the active species. The values of KOH(1.62±0.02 dm3 mol−1) and k (2.5±0.2 dm3 mol−1s−1), the formation constant of [Cr(OH)4]− from soluble Cr(OH)3 and the rate constant respectively, were determined at 27.0°C. The solubility of CrIII at pH>12 decreases with time, presumably due to slow formation of polynuclear CrIII species.

OXIDATION OF ALLYL ALCOHOL BY DIPERIODATONICKELATE(IV) IN AQUEOUS ALKALINEMEDIUM

SummaryCatalysis of the CeIV-allyl alcohol (AA) reaction in acid solution depends both on the of rate enhancement and product distribution on the catalyst used: OsVIII results mainly in acrolein, whereas PdII gives acrylic acid. The rate laws in the two cases also differ:viz., Equations 1 and 2K1 is the equilibrium constant of formation of the OsVIII-allyl alcohol complex and k1 is the rate constant of its oxidation by CeIV; K2 is the equilibrium constant for the formation of the CeIV-PdII-allyl alcohol complex and k2 is its rate constant of decomposition. Rate = K1k1[CeIV][AA][OsVIII]/(1+K1[AA]) (1) Rate = K1k1[CeIV][PdII]/(1+K2[CeIV]) (2)While OsVIII is effective in H2SO4 solution, aqueous HClO4 is needed for PdII. Both reactions proceed through formation of catalyst-allyl alcohol complexes with participation of free radicals. The details of these observations are discussed.

OSMIUM(VIII)-CATALYSED OXIDATION OF ALLYL ALCOHOL BY HEXACYANOFERRATE(III)IN ALKALINE MEDIUM

SummaryThe oxidation of AsIII by OsVIII or OsVI in aqueous H2SO4 follows the rate law:

OXIDATION OF DIMETHYLAMINE BY DIPERIODATO-NICKELATE(IV) IN AQUEOUS ALKALINE MEDIUM

d[Os^{IV} ]/dt = k_a K_a [oxidant][As^{III} ]/(1 + K_a [As^{III} ]).