Persulphate Ion Research Articles

Persulphate ion as a reagent for the detection of aromatic amines and related compounds on thin-layer chromatography

Persulphate ion as a reagent for the detection of aromatic amines and related compounds on thin-layer chromatography

Electron spin resonance studies. Part 56. An investigation of the role of aromatic radical-zwitterions and acyloxyl radicals in the one-electron oxidation of aromatic carboxylates and reduction of aromatic peroxyacids

The results are described of an e.s.r. investigation into the reactions of some aromatic radical-zwitterions +˙ArCO2–(derived by one-electron oxidation of benzoate and related ions with SO4–˙) and some aroyloxyl radicals ArCO2·(derived by reduction of some peroxybenzoic acids with TiIII). The radicals have been generated in an aqueous flow system at high pH; the nitromethane anion CH2:NO2– has been employed as a spin trap in order to elucidate the reaction mechanisms. Evidence is presented which accords with the suggestion that the species +˙ArCO2– and ArCO2˙ are distinct chemical entities, rather than canonical forms of a single intermediate. A variety of differently substituted aroyloxyl radicals (ArCO2˙) rapidly lose CO2 to give aryl radicals (Ar˙); an exceptional case is the rapid intramolecular hydrogen atom abstraction reactions of 2-methylbenzoyloxyl. There is evidence that the radical-zwitterions+˙ArCO2– undergo a variety of reactions depending on their structure: most undergo conversion into aroyloxyl radicals; in addition, 2- and 4-methyl-substituted derivatives also rapidly deprotonate (to yield the appropriate benzyl species), whereas methoxy-substituted species undergo ready one-electron reduction by TiIII. Rate constants are reported for the one-electron reduction of persulphate ion by titanium(III) at pH 2.5 and 9.

Colour changes in the uncatalyzed and Ag+ catalyzed oxidation of aromatic amines by persulphate ion

A scheme has been proposed for the identification of some of the aromatic amines, viz., aniline, ethyl and methyl aniline, diethyl and dimethyl aniline, α- and β-naphthylamine, o-, m- and p-toluidine, o-, m- and p-anisidine, m- and p-phenetidine, o-, m- and p-phenylenediamine, carbazole, benzidine, o-tolidine, quinoline and iso-quinoline, p-xylidine and diphenylamine. It is based on the reaction of an aqueous persulphate solution with an alcoholic solution of the amine.

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part III

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part III

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part II

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part II

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part III

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Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part II

Kinetics of Oxidation of Stannous Ion by Persulphate Ion. Part II

The silver-catalysed reduction of persulphate by oxalate in acid solution

The silver-catalysed reduction of persulphate by potassium oxalate in sulphuric acid solution is not attended by the induction period characteristics of the results of previous workers. The reaction is first order in persulphate ion and almost independent of oxalate ion concentration. This oxidation is much faster than other oxidations by persulphate. The energy and entropy of activation have been calculated and a probable mechanism has been suggested. Nitrate, sodium, potassium, ammonium and magnesium ions inhibit the reaction in the order given, while sulphate and hydrogen ions seem to accelerate the reaction. Urea slightly lowers the rate and Mn(II) is an anticatalyst.

The silver catalysed oxidation of manganous ion by persulphate

The oxidation of bivalent manganese by persulphate is very slow, but becomes fast in the presence of the silver ions. The product of oxidation is trivalent manganese which immediately disproportionates into manganese dioxide and divalent manganese. The kinetics were followed by running the reaction mixture into excess of oxalic acid and estimating the unused oxalic acid with permanganate. The reaction was found to be first order with respect to the persulphate ion and zero order with respect to the manganous ion. The salt effect is negative and exponential. The energy and entropy of activation have been calculated. The entropy is negative. In the presence of sulphuric acid the reaction mixture turns slightly red and the reaction rate appears to be much slowed down in sulphuric acid of strength 3·6 M and above. A mechanism has been suggested consistent with the observed facts.

8. Dissolution of metals and alloys. Part I. The dissolution of copper in solutions containing persulphate ion

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Molecular dissociation processes in solution. Part 4.—The rate of decomposition of persulphate ion and its catalysis by metal ions

Molecular dissociation processes in solution. Part 4.—The rate of decomposition of persulphate ion and its catalysis by metal ions

A NEW MECHANISM FOR PERSULPHATE OXIDATIONS

A new mechanism for oxidations by persulphate is presented, wherein it is postulated that the persulphate ion dissociates reversibly, by means of a heterolytic cleavage, into a sulphate ion and a molecule of sulphur tetroxide. Sulphur tetroxide is considered to be the active oxidizing species, combining reversibly with the substrate to form a complex whose subsequent decomposition gives the principal reaction products. The very small equilibrium concentration of sulphur tetroxide becomes the limiting factor in the rate of oxidation when a readily oxidizable substrate is present in relatively high concentration. The mechanism is applied to the data of Eager and Winkler for the oxidation of mercaptans, in which a limiting rate was attained above a certain mercaptan concentration. An empirical equation relating the rate constant to the mercaptan concentration is developed to fit the experimental data. Rate equations showing the rate dependence on mercaptan concentration are derived from the proposed mechanism and are found to be of the same form as the empirical equation. The mechanism is applied also to the persulphate oxidation of water.