Pratik K. Sen

Kinetics of the oxidation of hydroxylamine by platinum(IV)

Abstract The kinetics of the oxidation of hydroxylamine by platinum(IV) have been studied spectrophotometrically in sodium acetate-acetic acid buffer in the temperature range 25–40°C. The reaction is first order in both hydroxylamine and platinum(IV). The rate increases with decreasing acidity and dielectric constant. Different activation parameters of the reaction have been evaluated. Some possible reaction steps have been suggested.

Kinetics of oxidation of pyruvate ion by hexachloroiridate(IV)

Abstract The kinetics of oxidation of pyruvate ion by Ir(IV) have been studied spectrophotometrically in sodium acetate-acetic acid buffer. The reaction is first order with respect to (substrate) and (Ir(IV)). Hydrogen ion inhibits the rate of reaction. The addition of different salts accelerates the rate of reaction. The rate also increases with the increase in dielectric constant. The different activation parameters have been evaluated. The existence of a free radical intermediate has been demonstrated.

Kinetics and mechanism of oxidation of some aryl alcohols by acid bromate

Abstract The kinetics of oxidation of some substituted benzyl alcohols as well as the unsubstituted one by bromate ion in hydrochloric acid medium has been suggested. The results indicate that the reaction takes place by way of intermediate ester formation. Methoxy compounds react at much faster rates than the corresponding nitro substituted derivatives. The thermodynamic values associated with the equilibrium step and also for the slow step have been evaluated. A mechanism consistent with the experimental observations has been suggested.

Kinetics of oxidation of arsenic(III) by platinum(IV) in alkaline medium

Abstract The kinetics of the oxidation of arsenite ion by platinum(IV) have been studied spectrophotometrically in basic solutions at several temperatures. The rate increases with increase in pH as well as salt concentration and dielectric constant of the medium. The empirical rate law is − d[Pt(IV)] d t =k 3 [ Pt(IV)][As(III)][OH − ] The rate constant is 1910±80 (dm6 mol−2 s−1) at 25°C. The energy and entropy of activations are 42.3 (kJ mol−1) and −40.3 (J K−1 mol−1) respectively.

KINETICS AND MECHANISM OF THE OXIDATION OF ALKYL AND ARYL METHYL KETONES BY PERMANGANATE ION IN AQUEOUS ETHANOIC ACID

The kinetics of electron-transfer reactions between permanganate ion and ethyl and aryl methyl ketones have been studied in aqueous MeCO2H acid medium in the presence of HClO4 at different temperatures. For ethyl methyl ketone and XC6H4COMe (X = p-Cl, p-Br or p-NO2) the reaction obeys the rate law −d[MnO4−]/dt = (kKe[H+][MnO4−][RCO Me])/(1 + Ke[H+][RCOMe]).␣But the oxidations of XC6H4COMe (X = p-Me and p-OMe)␣follow the rate equation −d[MnO4−]/dt = k3[H+][MnO4−][RCOMe]. The reaction involves a fast pre-equilibrium with intermediate formation of a permanganate ester before the two-electron transfer, rate-determining, step. A number of thermodynamic parameters have been evaluated.

Evidence of esterification during the oxidation of some aromatic aldehydes by permanganate

SummaryThe permanganate ion oxidation of PhCHO in HClO4 medium is first order in [MnOinf4sup-], but of complex order with respect to [aldehyde] as well as [H+]. The influence of substituents on the reaction rate and mechanism has also been studied in 40% (v/v) aqueous AcOH and convincing evidence favours an ester formation mechanism. Thermodynamic values associated with 1∶1 intermediate ester formation and the activation parameters associated with the disproportionation steps involved have been evaluated.

Kinetics of oxidation of hypophosphite ion by platinum(IV) in an alkaline medium

SummaryThe kinetics of the oxidation of hypophosphite ion by platinum(IV) have been studied spectrophotometrically in alkaline medium at different temperatures. The rate increases as the pH increases and the empirical rate law applicable to the reaction is given by:-d[PtIV]/dt = k3[PtIV][H2PO2−][OH−]The rate constant is 2.17×10−3 (l2 mo−2s−1) at 40.5°. The energy and entropy of activation for the reaction are 104.2 kJ mol−1 and 28.5 JK−1mol−1 respectively.

KINETICS AND MECHANISM OF OXIDATION OF METHANOL BY ACID BROMATE

The kinetics of oxidation of methanol by bromate ion in hydrochloric acid medium has been investigated. A mechanism consistent with the experimental observations is suggested.AbstractИсследована кинетика окисления метанола броматным ионом в среде хлороводородной кислоты. Предложен механизм, согласующийся с экспериментальными результатами.

Relative reactivities of 1,2-dicarbonyl compounds towards permanganate in ethanoic acid medium. Mechanism of the oxidation processes

The oxidative behaviour of the 1,2-dicarbonyl compounds, viz., glyoxal, biacetyl and benzil, towards permanganate in ethanoic acid medium in the presence of HClO4 has been investigated. The reaction is first order with respect to MnO−4, substrate, as well as H+. The rate decreases with an increase in ionic strength. Different thermodynamic parameters have been evaluated. The protonated dialdehyde or diketone reacts with permanganate ion to form an intermediate ester which decomposes in a slow step to produce the corresponding carboxylic acid via C—C bond cleavage.

Kinetics of the oxidation of nitrous acid by tetrachloroaurate(III) inHCl

SummaryThe kinetics of the reaction between nitrous acid and gold(III) in an HCl medium was studied. The reaction was first order with respect to [AuIII] and [HNO2]·H+ and Cl- ions inhibit the rate and alkali metal ions have specific effects on the rate. The reaction appears to involve different gold(III) species, viz. AuClinf4sup−, AuCl3(OH2) and AuCl3(OH)−, which undergo a two-equivalent reduction to gold(I) leading to the formation of NOinf2sup+which under-goes rapid hydrolysis to give nitric acid.