Thermodynamic Quantities for the Different Steps Involved in the Oxidation of the Drug Ketorolac by Copper(III) Periodate Complex in Aqueous Alkaline Medium: A Mechanistic Approach

The oxidation of ketorolac (KET) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol⋅dm⁻³ was studied spectrophotometrically at 298 K. The reaction is of first order in [DPC] and has less than unit order in both [KET] and [alkali], and negative fractional order in [periodate]. The oxidation reaction in alkaline medium has been shown to proceed via a DPC-ketorolac complex, which decomposes slowly in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test, IR and GC-MS spectral studies. The reaction constants involved in the different steps of the mechanism were calculated at different temperatures, which yielded thermodynamic quantities for different steps of the reaction scheme. The activation parameters with respect to the slow step of the mechanism were computed and discussed; thermodynamic quantities were also determined.     

Kinetic and Mechanistic Study of the Oxidative Deamination and Decarboxylation of L-Valine by Alkaline Permanganate

 The kinetics of the oxidation of L-valine, (L-Val) by permanganate in aqueous alkaline medium at a constant ionic strength of 0.50 molċdm⁻³ was studied spectrophotometrically. The reaction is of first order in [permanganate ion] and of fractional order in both [L-Val] and [alkali]. Addition of products has no significant effect on the reaction rate. However, increasing ionic strength and decreasing dielectric constant of the medium increase the rate. The oxidation process in alkaline medium has been shown to proceed via two paths, one involving the interaction of L-valine with permanganate ion in a slow step to yield the products, and the other path the interaction of alkali with permanganate ion to give manganate. Some reaction constants involved in the mechanism were determined; calculated and observed rate constants agree excellently. The activation parameters were computed with respect to the slow step of the mechanism.     

Kinetics of the Oxidative Degradation of rac-Serine by Aqueous Alkaline Permanganate

Summary.  The kinetics of the oxidation of rac-serine by permanganate in aqueous alkaline medium was studied spectrophotometrically. The reaction showed first order kinetics in permanganate ion concentration and an order less than unity in rac-serine and alkali concentration. Increasing ionic strength and decreasing dielectric constant of the medium increase the rate. The oxidation reaction proceeds via an alkali-permanganate species which forms a complex with rac-serine. The latter decomposes slowly, followed by a fast reaction between a free radical of rac-serine and another molecule of permanganate to give the products. There is a good agreement between the observed and the calculated rate constants under different experimental conditions. Investigations at different temperatures allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism. Received October 15, 1999. Accepted (revised) December 15, 1999     

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.     

Kinetics and Mechanism of the Oxidation of Vanillin by Hexacyanoferrate(III) in Aqueous Alkaline Medium

The title reaction was investigated in aqueous alkaline medium. A first-order dependence in hexacyanoferrate(III) concentration and a fractional order in both vanillin and alkali were obtained at the concentrations studied. The added product, hexacyanoferrate(II), had a retarding effect on the rate of reaction. Ionic strength and dielectric constant of the reaction medium have little effect on the reaction rate. The effect of temperature on the rate of reaction has also been studied and activation parameters have been evaluated. A mechanism based on the experimental results is proposed and the rate law is derived. The reaction constants are calculated and used to regenerate the k_obs values, which are compared with the experimental values.     

Kinetics of osmium(VIII) catalysis of periodate oxidation of DMF in aqueous alkaline medium

The osmium(VIII) catalysed IO₄ ⁻ oxidation of DMF in aqueous alkaline medium follows the rate law:

Palladium(II) Catalysed Oxidation of l-proline by Heptavalent Manganese in Aqueous Alkaline Medium: A Free Radical Intervention and Decarboxylation

The kinetics of palladium(II) catalysed oxidation of l-proline by permanganate in alkaline medium was studied spectrophotometrically. The reaction between permanganate and l-proline in alkaline medium exhibits 2:1 stoichiometry (KMnO₄: l-proline). The reaction is first order with respect to [MnO₄⁻] and [Pd(II)], an apparent less than unit order in [alkali] and zero order in [l-proline] under the experimental conditions. Reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Addition of reaction products did not affect the rate significantly. A mechanism involving the intervention of a free radical generated by l-proline has been proposed. The reaction constants involved in the mechanism were evaluated. The activation parameters with respect to the slow step of the Scheme were evaluated and are discussed.     

Ruthenium(III) Catalyzed Oxidation Of Ethylenediaminetetraacetic Acid By N-Bromosuccinimide In Aqueous Alkaline Medium – A Kinetic And Mechanistic Study

The formation mechanism of microheterogeneous hydrogenation catalysts based on phosphinepalladium (II) complexes has been considered. According to elemental analysis, X-ray diffraction, electron microscopy, NMR, and IR spectroscopy, the catalyst is a nanoscale palladium organophosphorus matrix and (or) palladium phosphide with immobilized palladium clusters. This revised version was published online in June 2006 with corrections to the Cover Date.     

Permanganate oxidation of chromium(III) in aqueous alkaline medium: a kinetic study by the stopped-flow technique

Permanganate oxidation of CrIII in aqueous medium (pH>;12) at25°C has been studied by the stopped-flow technique, combined with a rapid scan spectrophotometry, and obeys the rate equation:¶ where K is the formation constant of the MnVII-CrIII adduct and k is the rate constant for its decomposition. The rate is independent of [OH–]. The active oxidant and reductant species are understood to be [MnO4]– and [Cr(OH)4]–, respectively.