Electron transfer reaction rates and equilibria of the carbonate and sulfate radical anions

Huie, Robert E.; Clifton, Carol L.; Neta, P.

doi:10.1016/1359-0197(91)90065-a

Cited by 197 publications

(228 citation statements)

References 17 publications

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“…Furthermore, the alkoxy radical can undergo fragmentation to yield a formaldehyde (CH 2 O) and a sulfate radical anion (SO 4 •− ). 25 As shown in Figure 1, neither functionalization nor fragmentation products are detected. Formaldehyde has a mass which is below the mass range of the mass spectrometer and, once formed, it is likely partitioned back to the gas phase due to its high volatility.…”

Section: Reaction Mechanisms: Oh Reaction With Sodium Methyl Sulfate 15mentioning

confidence: 96%

“…This can be attributed to a small fraction of particle mass lost via the formation and volatilization of formaldehyde. Overall, we firstly demonstrate that 25 the heterogeneous OH oxidation of an organosulfate can lead to the formation of sulfate radical anion and produce inorganic sulfate. Fragmentation processes and sulfate radical anion chemistry play a key role in determining the compositional evolution of sodium methyl sulfate during heterogeneous OH oxidation.…”

mentioning

confidence: 99%

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Importance of Sulfate Radical Anion Formation and Chemistry in Heterogeneous OH Oxidation of Sodium Methyl Sulfate, the Smallest Organosulfate

Kwong¹,

Chim²,

Davies³

et al. 2017

Preprint

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Abstract.Organosulfates are important organosulfur compounds present in atmospheric particles. While the abundance, 10 composition, and formation mechanisms of organosulfates have been extensively investigated, it remains unclear how they transform and evolve throughout their atmospheric lifetime. To acquire a fundamental understanding of how organosulfates chemically transform in the atmosphere, this work investigates the heterogeneous OH radical-initiated oxidation of sodium methyl sulfate (CH 3 SO 4 Na) droplets, the smallest organosulfate detected in atmospheric particles, using an aerosol flow tube reactor at a high relative humidity of 85 %. Aerosol mass spectra measured by a soft atmospheric pressure ionization source 15 (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer showed that neither functionalization nor fragmentation products are detected. Instead, the ion signal intensity of the bisulfate ion (HSO 4 − ) has been found to increase significantly after OH oxidation. We postulate that sodium methyl sulfate tends to fragment into a formaldehyde (CH 2 O) and a sulfate radical anion (SO 4•− ) upon OH oxidation. The formaldehyde is likely partitioned back to the gas phase due to its high volatility. The sulfate radical anion, similar to OH radical, can abstract a hydrogen atom from 20 neighboring sodium methyl sulfate to form the bisulfate ion, contributing to the secondary chemistry. Kinetic measurements show that the heterogeneous OH reaction rate constant, k, is (3.79 ± 0.19) × 10 -13 cm 3 molecule -1 s -1 with an effective OH uptake coefficient, γ eff , of 0.17 ± 0.03. While about 40 % of sodium methyl sulfate is being oxidized at the maximum OH exposure (1.27 × 10 12 molecule cm −3 s), only a 3 % decrease in particle diameter is observed. This can be attributed to a small fraction of particle mass lost via the formation and volatilization of formaldehyde. Overall, we firstly demonstrate that 25 the heterogeneous OH oxidation of an organosulfate can lead to the formation of sulfate radical anion and produce inorganic sulfate. Fragmentation processes and sulfate radical anion chemistry play a key role in determining the compositional evolution of sodium methyl sulfate during heterogeneous OH oxidation. 35Atmos. Chem. Phys. Discuss., https://doi

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Section: Reaction Mechanisms: Oh Reaction With Sodium Methyl Sulfate 15mentioning

confidence: 96%

mentioning

confidence: 99%

Importance of Sulfate Radical Anion Formation and Chemistry in Heterogeneous OH Oxidation of Sodium Methyl Sulfate, the Smallest Organosulfate

Kwong¹,

Chim²,

Davies³

et al. 2017

Preprint

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“…The CO 3 C À radical is a one-electron oxidant [E 0 (CO 3 C À / CO 3 2À ) = 1.59 V vs. NHE [52] ] and has been found to oxidize guanines with high selectivity in the sequence d(AACGC-GAATTCGCGTT), which readily forms self-complementary duplexes in aqueous solutions. [27] Although an effect similar to that observed in the case of the BPTC + radical ( Figure 2) might have been expected in view of the high oxidation potential of the CO 3 C À radical, it is evident that the k 5 value of the electron transfer rate (Table 1) is not particularly sensitive to the presence or absence of guanines.…”

mentioning

confidence: 99%

Mechanisms of Oxidation of Guanine in DNA by Carbonate Radical Anion, a Decomposition Product of Nitrosoperoxycarbonate

Lee

Yun

Kim

et al. 2007

Chemistry A European J

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Peroxynitrite is produced during inflammation and combines rapidly with carbon dioxide to yield the unstable nitrosoperoxycarbonate, which decomposes (in part) to CO(3) (.-) and (.)NO(2) radicals. The CO(3) (.-) radicals oxidize guanine bases in DNA through a one-electron transfer reaction process that ultimately results in the formation of stable guanine oxidation products. Here we have explored these mechanisms, starting with a spectroscopic study of the kinetics of electron transfer from 20-22mer double-stranded oligonucleotides to CO(3) (.-) radicals, together with the effects of base sequence on the formation of the end-products in runs of one, two, or three contiguous guanines. The distributions of these alkali-labile lesions were determined by gel electrophoresis methods. The cascade of events was initiated through the use of 308 nm XeCl excimer laser pulses to generate CO(3) (.-) radicals by an established method based on the photodissociation of persulfate to sulfate radicals and the oxidation of bicarbonate. Although the Saito model (Saito et al., J. Am. Chem. Soc. 1995, 117, 6406-6407) predicts relative ease of one-electron oxidations in DNA, following the trend 5'-GGG > 5'-GG > 5'-G, we found that the rate constants for CO(3) (.-)-mediated oxidation of guanines in these sequence contexts (k(5)) showed only small variation within a narrow range [(1.5-3.0)x10(7) M(-1) s(-1)]. In contrast, the distributions of the end-products are dependent on the base sequence context and are higher at the 5'-G in 5'-GG sequences and at the first two 5'-guanines in the 5'-GGG sequences. These effects are attributed to a combination of initial hole distributions among the contiguous guanines and the subsequent differences in chemical reaction yields at each guanine. The lack of dependence of k(5) on sequence context indicates that the one-electron oxidation of guanine in DNA by CO(3) (.-) radicals occurs by an inner-sphere mechanism.

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“…These reactive oxygen species can initiate propagation and termination of chain reactions in which organics are partially and even fully decomposed. 7 Peroxydisulfate anions (S 2 O 8 2À ) are formed during the dissociation of peroxydisulfate salts in aqueous solution. Because of the low solubility of potassium peroxydisulfate in water, sodium peroxydisulfate (SPDS) is the most common and suitable form used in degradation processes.…”

Section: Introductionmentioning

confidence: 99%

Degradation kinetics and mechanism of pentoxifylline by ultraviolet activated peroxydisulfate

et al. 2018

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Degradation of pentoxifylline (PTX) by sodium peroxydisulfate (SPDS) assisted by UV irradiation has been investigated in deionized water. The treatment was more favorable over direct photolysis or peroxydisulfate oxidation alone. The effects of various parameters, including different dosage of oxidant agent, PTX concentration, initial solution pH levels, and the presence of inorganic ions like chloride, nitrate and carbonate have been evaluated. The rate of PTX decomposition depends on the oxidant agent dose. The highest degradation was determined at pH 10.5, which can be explained by the generation of additional hydroxyl radicals (HOc) in the reaction between sulfate radicals and hydroxide ions. The presence of inorganic ions, especially the carbonate ions quench valuable sulfate radicals and have successfully retarded the PTX decomposition. Six PTX oxidation products were identified using UPLC-QTOF-MS for trials in a basic environment. The main degradation product (3,7-dimethyl-6-(5-oxohexyloxy)-3,7-dihydro-2H-purin-2-one) was isolated by column chromatography and identified by 1 HNMR and LC MS analyzes.

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Electron transfer reaction rates and equilibria of the carbonate and sulfate radical anions

Cited by 197 publications

References 17 publications

Importance of Sulfate Radical Anion Formation and Chemistry in Heterogeneous OH Oxidation of Sodium Methyl Sulfate, the Smallest Organosulfate

Importance of Sulfate Radical Anion Formation and Chemistry in Heterogeneous OH Oxidation of Sodium Methyl Sulfate, the Smallest Organosulfate

Mechanisms of Oxidation of Guanine in DNA by Carbonate Radical Anion, a Decomposition Product of Nitrosoperoxycarbonate

Degradation kinetics and mechanism of pentoxifylline by ultraviolet activated peroxydisulfate

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