Kinetics and mechanism of the reactions of the superoxide ion in solutions. I. Absorption spectra and interaction with solvents and cations

Afanas’ev, Igor B.; Kuprianova, N. S.; Polozova, N. I.

doi:10.1002/kin.550151008

Cited by 11 publications

(7 citation statements)

References 25 publications

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“…Figure 1 shows typical UV-vis spectra of O 2 -, which was electrogenerated in a 0.1 M TEAP/AN solution containing 41.1 mM H 2 O. From this figure it is obvious that the maximum absorption wavelength λ max is 250 nm and is almost comparable to those (249-255 nm) previously reported for O 2in AN 2, [10][11][12][13] and that the absorbance gradually decreases with time owing to the water-induced disproportionation (vide infra). The observed optical absorption is ascribed to 2π g f 2π u electric transition of O 2 -.…”

Section: Resultssupporting

confidence: 63%

Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents

et al. 1996

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The water-induced disproportionation of the electrogenerated superoxide ion (O2 -) in acetonitrile, dimethylformamide, and dimethyl sulfoxide media containing various concentrations of water as a Brønsted acid has been examined by UV−vis spectroscopy. Analysis of the kinetics as a function of O2 - and water concentrations and of the measurement time demonstrated that the disproportionation of O2 - by water in these media obeys a common mechanism: O2 - + H2O ⇄ HO2 • + OH- (k 1, k -1) HO2 • + O2 - → HO2 - + O2 (k 2) (HO2 •, hydroperoxyl radical; HO2 -, hydrogen peroxide anion). The solvent dependence of the obtained kinetic parameters of (k 1/k -1)k 2, k 1 and k -1/k 2 is discussed in terms of the solvation of O2 - and H2O as well as the effective acidities of H2O in different aprotic solvents.

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Section: Resultssupporting

confidence: 63%

Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents

et al. 1996

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“…Procedures of the preparation of the 0, solutions and of the purification of solvents were the very same as in the preceding paper [4]. Twice distilled water was used.…”

Section: Methodsmentioning

confidence: 99%

Kinetics and mechanism of the reactions of the superoxide ion in solutions. II. The kinetics of protonation of the superoxide ion by water and ethanol

Afanas’ev¹,

Kuprianova²

1983

Int J of Chemical Kinetics

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The rate constants for the protonation of "free" (that is, solvated) superoxide ions by water and ethanol are equal to 0.5-3.5 X lO-~M-l.s-' in DMF and AN at 20'. It has been found that the protonation rates for the ion pairs of 0; with the BudN+ cation are much slower than those for "free" 0,. It is suggested that the effects of aprotic solvents on the protonation rates of 0; are mainly due to the fact that the proton donors form solvated complexes of different stability in these solvents.

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“…The rate of reaction (1) was determined by following spectrophotometrically the disappearance of both reactants: super-…”

Section: Resultsmentioning

confidence: 99%

Kinetics and mechanism of the reactions of superoxide ion in solution. Part 5. Kinetics and mechanism of the interaction of superoxide ion with vitamin E and ascorbic acid

Afanas’ev¹,

Grabovetskii²,

Kuprianova³

1987

J. Chem. Soc., Perkin Trans. 2

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The reactions of electrochemically generated 02-' with a-tocopherol and a-tocopheryl acetate have been studied in acetonitrile and with ascorbic acid in acetonitrile and mixed acetonitrile-water solvents. It was found that both a-tocopherol and ascorbic acid react with superoxide ion via a deprotonation mechanism to form the corresponding anions. On subsequent steps of the process these anions are oxidized by 0, to form 02-* The mechanism of the oxidation of ascorbate anion depended on the solvent composition: in aqueous solution the reaction proceeded only in the presence of Fe3+ ion, but in acetonitrile a direct one-electron transfer from the ascorbate anion to dioxygen was observed. Both mechanisms were suppressed to a considerable extent in mixed solvents.

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Kinetics and mechanism of the reactions of the superoxide ion in solutions. I. Absorption spectra and interaction with solvents and cations

Cited by 11 publications

References 25 publications

Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents

Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents

Kinetics and mechanism of the reactions of the superoxide ion in solutions. II. The kinetics of protonation of the superoxide ion by water and ethanol

Kinetics and mechanism of the reactions of superoxide ion in solution. Part 5. Kinetics and mechanism of the interaction of superoxide ion with vitamin E and ascorbic acid

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