Does Peroxynitrite Partition between Aqueous and Gas Phases? Implication for Lipid Peroxidation

Rudakov, E. S.; Lobachev, V. L.; Geletii, Yurii V.

doi:10.1021/tx010060y

Cited by 13 publications

(18 citation statements)

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“…As a consequence of change in the concentration of the direct reagent during the course of the reaction due to the rapid decomposition of PA, the kinetics for the consumption of the hydrocarbons in the H 2 O 2 /NaNO 2 system is not first-order relative to the substrate even under conditions of a large excess of hydrogen peroxide and sodium nitrite relative to RH [1,9]. We used a competitive method [14] to exclude the unknown concentration of the reagent, which changes rapidly over time.…”

Section: Resultsmentioning

confidence: 99%

“…The oxidation of hydrocarbons by peroxynitrous acid proceeds simultaneously in both phases of the sealed reactor in the aqueous solution/gas phase system under the conditions of the kinetic distributional method. According to our previous work [1,9], the alkanes are found and react with PA predominantly in the gas phase due to low solubility (high a RH values). Even for the lowest experimental values l = 0.32, the contribution of the liquid-phase pathway for these hydrocarbons is 5-15% of the total rate of consumption of the substrate.…”

Section: Resultsmentioning

confidence: 99%

“…The kinetic distributional method does not permit us to determine the relative rate constants for the oxidation of alkanes by peroxynitrous acid in aqueous solution due to the low contribution of the liquid-phase pathway to the overall rate of hydrocarbon consumption [1,9]. This problem was solved by the direct measurement of the relative liquid-phase rate constants by the syringe reactor method (in the absence of a gas phase) in the phosphate system ([H 3 PO 4 ] = 0.002 M, [KH 2 PO 4 ] = 0.064 M) [10,11] with initial pH 3.36.…”

Section: Resultsmentioning

confidence: 99%

“…A linear relationship is found in the entire series of alkanes, alkenes, and alkylbenzenes studied for both phases between the relative rate constants of the two reactions with the same slope [1, 9,10]. In previous work [1, 9,11], we have shown that the initial products of reaction (2) with cyclohexane are cyclohexyl radicals, which dimerize to give dicyclohexyl and are oxidized to cyclohexanol and cyclohexanone.…”

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confidence: 95%

“…We were the first to undertake a systematic investigation of the kinetics of the reactions of peroxynitrite with hydrocarbons and found that alkanes, alkenes, and alkylbenzenes are oxidized by aqueous solutions of peroxynitrous acid when pH < 7.5 and by a model H 2 O 2 -HNO 2 system (pH » 4) [1,9]. These reactions in the two-phase gas/solution system proceed concurrently in both phases.…”

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Kinetics and mechanism of the reactions of C6H12, C5H10 and C6D12 cycloalkanes with peroxynitrous acid in aqueous solution and the gas phase

2008

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temperature dependence of these ratios in the gas-phase reactions of cycloalkanes with peroxynitrous acid and OH radicals are identical. The same result was obtained for the reactions in aqueous solution. These data are in accord with the conclusion that OH ⋅ radicals formed in the homolysis of the HO-ONO bond are the active species in the reactions of HOONO with hydrocarbons in aqueous solution and in the gas phase.Peroxynitrous acid HOONO (PA) has been known for more than 100 years as an unstable intermediate in the oxidation of nitrites and nitrates by hydrogen peroxide in acid media [1]:(1)In vivo, the peroxynitrite anion ( -OONO) formed in the rapid recombination (k = (3.8-19)·10 9 L/mol·s [1, 2]) of nitrogen oxide (NO) and the superoxide anion (O 2 & − ) plays an important role in physiological processes, including the oxidation of alkyl and alkene C-H bonds of lipid membrane polyunsaturated fatty acids [1,3]. The anion is relatively stable in alkaline solutions, but the acid, HOONO, (pK a = 6.8) rapidly isomerizes to HNO 3 (t 1/2 » 1.2-1.3 s) [1,4]. The detailed mechanism of the isomerization is unclear [1]. Doubt has recently been cast on the previously accepted homolytic mechanism involving the intermediate formation of OH and NO 2 radicals [2]. Various workers [1,3,5,6] have explained the high activity of PA in reactions with organic compounds by 1) the formation of "OH-radical-like" species in the decomposition of HOONO, 2) by the formation of a nitronium cation NO 2 + upon catalysis by metal ions, and 3) by the direct reaction of HOONO or OONO -with the substrate.The reactions have been studied previously only with strong reducing agents. Prior to our work, only two studies have published concerning the products of the oxidation of cyclohexane, cyclohexene [7], and arenes [8] in the H 2 O 2 -HNO 2 system generating PA in situ.We were the first to undertake a systematic investigation of the kinetics of the reactions of peroxynitrite with hydrocarbons and found that alkanes, alkenes, and alkylbenzenes are oxidized by aqueous solutions of peroxynitrous acid when pH < 7.5 and by a model H 2 O 2 -HNO 2 system (pH » 4) [1,9]. These reactions in the two-phase gas/solution system 0040-5760/08/4402-0109

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 95%

mentioning

confidence: 99%

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Kinetics and mechanism of the reactions of C6H12, C5H10 and C6D12 cycloalkanes with peroxynitrous acid in aqueous solution and the gas phase

2008

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Kinetics and Mechanism of the Oxidation of Alkanes and Alkenes with Peroxynitrous Acid in Aqueous Solution-Gas Phase Systems

Lobachev

Rudakov

2005

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Oxidation of Diethyl Sulfide in Aqueous Solutions by Peroxynitrite and the H2O2-NO−2 System

2005

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It was found that nitrite anions are effective activators of hydrogen peroxide in the reaction with diethyl sulfide. The observed kinetics are consistent with the proposed intermediate formation of peroxynitrous acid (ONOOH). The rate constants for the reaction of diethyl sulfide Et 2 S with the acid ONOOH (k 0 = 1.8×10 3 L/mol×s) and with the anion ONOO -(k -= 6×10 -2 L/mol×s) are respectively 10 5 and three times higher than with hydrogen peroxide.The search for new methods of selective oxidation of thioethers is of great significance for solution of the problem of the decomposition of pesticides and toxic substances in which the active components are sulfides. The hypochlorous acid derivatives widely used for these purposes -chloramines -are extremely toxic and aggressive compounds [1]. It is of great interest to use the ecologically clean hydrogen peroxide, which itself has low reactivity but forms highly active peroxy acids in conjunction with catalysts (bicarbonates [2, 3], molybdates [4], and other compounds). We found that nitrite anions are effective activators of hydrogen peroxide in reaction with diethyl sulfide.In 1901 it was found [5] that in acidic media nitrites are oxidized to nitrates through the intermediate formation of the unstable peroxynitrous acid (ONOOH), which has unusually high oxidizing power. The formation of ONOOH in the H + /HNO 2 /H 2 O 2 system takes place according to the following mechanism [6]:The surge of interest in the chemistry of peroxynitrite (PN) in the last 15 years is due to the discovery of its formation in vivo during the rapid recombination of NO and O 2 & − and its important role in biochemical processes [7]. [According to IUPAC nomenclature peroxynitrous acid has the name hydrogen oxoperoxynitrate, while the peroxynitrite anion ONOO -is oxoperoxynitrate(1-). The usually employed term "peroxynitrite" applies both to the anion and to the acid.] Peroxynitrite is relatively stable in alkaline media, while under physiological conditions it is partly protonated to peroxynitrous acid (pK a = 6.8 [8]), which soon decomposes (k dec = 1.2 s -1 , pH 7.0 at 25°C [8]) with the formation of nitrate. The high reactivity of PN is usually attributed to the formation, during homolysis of the ONO-OH bond, of "hydroxyl-like" radicals, capable of oxidizing even such inert molecules as alkanes under mild conditions [9].Thioethers are oxidized both by peroxynitrous acid and by its anion with the formation of sulfoxides and NO 2 − [10, 11].In the reaction of dimethyl sulfide (Me 2 S) with ONOO -the yield of Me 2 SO and nitrite amounts to 100% on PN, while in 302 0040-5760/05/4105-0302

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Does Peroxynitrite Partition between Aqueous and Gas Phases? Implication for Lipid Peroxidation

Cited by 13 publications

References 35 publications

Kinetics and mechanism of the reactions of C6H12, C5H10 and C6D12 cycloalkanes with peroxynitrous acid in aqueous solution and the gas phase

Kinetics and mechanism of the reactions of C6H12, C5H10 and C6D12 cycloalkanes with peroxynitrous acid in aqueous solution and the gas phase

Kinetics and Mechanism of the Oxidation of Alkanes and Alkenes with Peroxynitrous Acid in Aqueous Solution-Gas Phase Systems

Oxidation of Diethyl Sulfide in Aqueous Solutions by Peroxynitrite and the H2O2-NO−2 System

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