Oxidation of monoglyceride, diglyceride, and triglyceride monolayers by aqueous potassium permanganate solution

Studies were carried out on the oxidative degradation of monoolein, monolinolein, diolein, dilinolein, triolein and trilinolein monolayers by injecting KMnO₄ solution under the monolayers. The effect of the initial surface pressure on oxidative degradation was also studied by measuring changes in the surface pressure and surface potential with time. The surface shear viscosities of these six lipids were measured in order to predict their molecular interactions at the air/water interface. The rates of oxidation for these lipids were found to be in the following order: dilinolein> monolinolein> monoolein> trilinolein> diolein> triolein. Interestingly, the surface shear viscosities of these six lipids were found to decrease in the same order. In the present study, an attempt has been made to correlate the effect of the initial surface pressure, the number of double bonds and the number of hydroxyl groups with the oxidation of these lipids by potassium permanganate solution.     

Kinetics and mechanisms of the oxidation by permanganate of L-Phenylalanine

The oxidation of L-Phenylalanine by permanganate ion in aqueous phosphate buffers is autocatalized by the inorganic reaction product, which is stabilized in solution by adsorption of phosphate ions on its surface. This product is a soluble form of colloidal manganese dioxide. The rate of the noncatalytic reaction pathway is first-order in both the oxidizing and reducing agent. It is not affected by potassium chloride addition to the solution, but by phosphate addition. The rate increases with the pH of the medium. The autocatalytic pathway is first-order in both permanganate ion and colloidal manganese dioxide, (the permanganate ion according to the Langmuir isotherm). The autocatalytic rate increases with reductant concentration (follows the Langmuir adsorption isotherm). It is not affected by potassium chloride addition to the solution, whereas an increase in the phosphate concentration results in an increase in the rate with the same pH of the medium. Mechanisms consistent with the experimental data are proposed.     

Oxidation of higher alcanols by tetra-1-butylammonium permanganate

Summary Oxidations of hexan-1-ol, hexan-2-ol, hexan-3-ol, heptan-1-ol, heptan-2-ol, octan-1-ol, and octan-2-ol with tetra-1-butylammonium permanganate, dissolved in the same alcohols, proceed partly autocatalytically. The rate constants of both catalytic and non-catalytic reactions have been evaluated. Colloidal manganese dioxide, one of the reaction products, has been identified as the catalyst.

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Oxidation höherer Alkanole mit Tetra-1-butylammoniumpermanganat

Zusammenfassung Die Oxidation von 1-Hexanol, 2-Hexanol, 3-Hexanol, 1-Heptanol, 2-Heptanol, 1-Octanol und 2-Octanol durch Tetra-1-butylammoniumpermanganat, gelöst in diesen Alkoholen, verläuft teilweise autokatalytisch. Die Geschwindigkeitskonstanten von katalytischen und nichtkatalytischen Teilreaktionen wurden bestimmt. Das kolloidale Mangandioxid, eines der Reaktionsprodukte, konnte als Katalysator identifiziert werden.

     

Kinetics and mechanism of the oxidation of acetylacetone by permanganate ion

The kinetics and mechanism of permanganate ion oxidation of acetylacetone (Acac) was studied in acidic and alkaline media. The rate constants for keto, enol, and enolate anions were determined and discussed. Delocalization of the π‐electrons of the double bond by conjugation results in a slower oxidation rate of enol than can be usually observed for unsaturated compounds. In the case of the keto form, the acid‐catalyzed nucleophilic attack of permanganate ion occurs on the carbonyl‐C atom. For enolate anion a mechanism with basis‐catalyzed electron abstraction is suggested. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 444–450, 2006     

Kinetics and mechanism of sulfite oxidation by permanganate in basic medium

The kinetics of the permanganate-sulfite redox reaction has been studied in the alkaline medium using a stopped-flow technique. In the pH range 10 to 12 the reaction was found to obey the rate expression: ?½d[MnO₄^?]/dt = (k₁ + k₂[OH^?]) [MnO₄^?] [SO₃^2?]. Mechanisms for the two paths involving the formation of a (O₃MnOSO₃)^3? complex prior to the rate-determining step are consistent with the data. © John Wiley & Sons, Inc.     

Oxidation rate of saturated hydrocarbons by permanganate in aqueous solutions

Conclusions The reaction for the oxidation of alkanes in aqueous permanganate solutions is first order in both substrate and oxidizing agent. The reaction rate constants were measured for a number of C₃-C₇ normal, iso-, and cycloalkanes. The normal type of selectivity is fulfilled: the tertiary C-H bonds are more active, while the primary C-H bonds are less active than the secondary C-H bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1654–1656, July, 1982.     

Kinetics and mechanism of the oxidation of substituted benzylamines by cetyltrimethylammonium permanganate

Oxidation of meta- and para-substituted benzylamines by cetyltrimethylammonium permanganate (CTAP) to the corresponding aldimines is first order with respect to both the amine and CTAP. Oxidation of deuteriated benzylamine (PhCD₂NH₂) exhibited the presence of a substantial kinetic isotope effect (k _H /k _D = 5.60 at 293 K). This confirmed the cleavage of an α-C-H bond in the rate-determining step. Correlation analyses of the rates of oxidation of 19 monosubstituted benzylamines were performed with various single and multiparametric equations. The rates of the oxidation showed excellent correlations in terms of Yukawa—Tsuno and Brown’s equations. The polar reaction constants are negative. The oxidation exhibited an extensive cross-conjugation, in the transition state, between the electron-donating substituents and the reaction centre. A mechanism involving a hydride-ion transfer from the amine to CTAP in the rate-determining step has been proposed.     

Oxidation of sulphides with alkaline potassium permanganate

Summary Sulphides are oxidised with potassium permanganate in alkaline medium to give dithionate. A method based upon this reaction is proposed for the determination of sulphides. The method consists in mixing the sulphide solution with an excess of permanganate in presence 1–2 M NaOH and 0.2 g telluric acid. The excess permanganate is then treated with ferrous ammonium sulphate in acid medium and the excess ferrous titrated with permanganate.     

Alginate polyelectrolyte ionotropic gels. XVIII. Oxidation of alginate polysaccharide by potassium permanganate in alkaline solutions: Kinetics of decomposition of intermediate complex

The kinetics of decomposition of [Alg · Mn ^VIO₄^2?] intermediate complex have been investigated spectrophotometrically at a constant ionic strength of 0.5 mol dm^?3. The decomposition reaction was found to be first-order in the intermediate concentration. The results showed that the rate of reaction was base-catalyzed. The kinetic parameters have been evaluated and found to be ΔS^? = ?103.88±6.18 J mol^?1 K^?1, ΔH^? = 51.61 ± 1.02 kJ mol^?1, and ΔG^? = 82.57 ± 2.86 kJ mol^?1, respectively. A reaction mechanism consistent with the results is discussed. © 1993 John Wiley & Sons, Inc.     

Kinetics of Pindolol Oxidation by Peroxodisulfate

The kinetics of oxidation of pindolol by peroxodisulfate (PDS) in sulfuric acid and 40%(v/v) methanol + water solvent has been investigated. The pH profile of the rate constant was also investigated. It has been found that the reaction proceeds only in the pH range 0 to 4. A mechanism was proposed for the oxidation reaction; the reaction starts by the attack of peroxodisulfate (PDS) to form an indoleninic species that can rearrange into an indoxyl species. Once the indoxyl intermediate is formed, it can follow different paths leading to different products, depending on the acidity and PDS concentration. At low acid concentration, oxipindolol is formed whereas at high acid concentration dioxipindolol forms instead. Dioxipindolol can dimerize to form the indigo form of pindolol. A polar mechanism was proposed for the oxidation reaction, and the thermodynamic parameters were determined.     

Oxidation kinetics of crystal violet by potassium permanganate in acidic medium

The oxidation kinetics of crystal violet (a triphenylmethane dye) by potassium permanganate was focused in an acidic medium by the spectrophotometric method at 584 nm. The oxidation reaction of crystal violet by potassium permanganate is carried out in an acidic medium at different temperatures ranging within 298–318 K. The kinetic study was carried out to investigate the effect of the concentration, ionic strength and temperature. The reaction followed first order kinetics with respect to potassium permanganate and crystal violet and the overall rate of the reaction was found to be second order. Thermodynamic activation parameters like the activation energy (E_a), enthalpy change (ΔH*), free energy change (ΔG*), and entropy change (ΔS*) have also been evaluated.     

Kinetics and mechanism of the oxidation of substituted mandelic acids by acid permanganate

The oxidation of mandelic acid and nine monosubstituted mandelic acids by acid permanganate, in the presence of fluoride ions, have been studied. The reaction is of first order with respect to each the oxidant, the substrate and hydrogen ions. The kinetic isotope effect, k_H/k_D = 3·76 at 25°. The oxidation exhibits a reaction constant ?+= ?2·23 ± 0·07 at 25°. The oxidation does not induce polymerisation of acrylonitrile and does not show any solvent isotope effect. The activation enthalpies entropies are linearly related (r = 0·979). A mechanism involving transfer of a hydride ion to the oxidant is proposed.     

Kinetics and mechanism of the oxidation of selenium(IV) by permanganate

Summary The oxidation of selenium(IV) by permanganate has been studied kinetically in acid, neutral and alkaline media. The reaction exhibits unit-order dependence on selenium(IV) and permanganate in all the three media. Manganese(VI) retards the reaction in alkaline medium. The rate-limiting step is the same in all the three media, but the stoichiometry is different, being 2:1 in alkaline medium, 2:3 in neutral medium and 2:5 in acid medium. Evidence has been obtained for a one electron-transfer in the rate-determining step.     

Oxidation with permanganate in presence of fluoride: Determination of hypophosphite

A rapid method is described for the determination of hypophosphite by oxidation with permanganate in acid medium in the presence of fluoride to prevent formation of insoluble oxides of manganese. The optimum conditions for visual and potentiometric end-point detection are given. Hypophosphite is oxidized to H(2)PO(-)(3). Under optimum conditions the titrations are fast and exhibit a reasonable potential change at the end-point. The method demonstrates the feasibility of determining amounts of H(2)PO(-)(2) corresponding to 0.08-7 mg of phosphorus.     

Kinetics of the base-catalyzed permanganate oxidation of benzaldehyde

The kinetics of the base-catalyzed permanganate oxidation of benzaldehyde have been reexamined. The rate is proportional to the first power of the aldehyde and permanganate concentrations, and there are terms that are zero order, first order, and second order in hydroxide ion. The reaction has an isotope effect, and the effect of substituents gives rho = +1.58. The possible mechanisms for the reaction are discussed in the context of ab initio calculations at the B3P86/6-311+G and MP2/6-31G theoretical levels, and both one- and two-electron processes are possible. Benzaldehyde hydrate dianion is calculated to have a remarkably small C-H bond dissociation energy.