Reactions of Phosphate Radicals with Monosubstituted Benzenes. A Mechanistic Investigation

Rosso, Janina A.; Caregnato, Paula; Mora, Verónica C.; González, Mónica C.; Mártire, Daniel O.

doi:10.1002/hlca.200390203

Cited by 29 publications

(39 citation statements)

References 32 publications

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“…A similar reaction path is reported for the sulphate radical reaction with chlorobenzene. [25] Our experimental results show that formation and decay of 3-substituted hydroxypyridine radical adducts are not sensitive, within the experimental error, to the presence of molecular oxygen in air-saturated solutions. Therefore, oxidation of the pyridine moiety mainly rely on the disproportionation of the hydroxypyridine radical adducts to yield the corresponding pyridinols (see Scheme 1), in agreement with the nature of the products observed in experiments with air-saturated solutions.…”

mentioning

confidence: 57%

“…[24] However, SO 4 C À radicals are known to react with high selectivity with substituted benzenes by an addition-elimination pathway yielding hydroxycyclohexadienyl radicals (HCHD). [25] Therefore, SO 4 C À radical addition to the pyridine cycle and further elimination to yield hydroxypyridine radical adducts may be a probable reaction pathway, as shown in Scheme 1. A similar reaction scheme should apply for the protonated pyridine molecules.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, HCHD radicals, reversibly react with molecular oxygen to yield peroxyl radicals, which after rearrangement to endoperoxides lead to the formation of open-chain oxidized products. [25] Therefore, substituted benzenes are expected to be more easily mineralized than pyridines substituted at a meta site of the N atom.…”

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confidence: 99%

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Reactions of Sulphate Radicals with Substituted Pyridines: A Structure–Reactivity Correlation Analysis

et al. 2007

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The kinetics of the oxidation of pyridine, 3-chloropyridine, 3-cyanopyridine, 3-methoxypyridine and 3-methylpyridine mediated by SO4 () radicals are studied by flash photolysis of peroxodisulphate, S2O8(2-), at pH 2.5 and 9. The absolute rate constants for the reactions of both, the basic and acid forms of the pyridines, are determined and discussed in terms of the Hammett correlation. The monosubstituted pyridines react about 10 times faster with sulphate radicals than their protonated forms, the pyridine ions. The organic intermediates are identified as the corresponding hydroxypyridine radical adducts and their absorption spectra compared with those estimated employing the time-dependent density functional theory with explicit account for bulk solvent effects. A reaction mechanism which accounts for the observed intermediates and the pyridinols formed as products is proposed.

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confidence: 57%

Section: Discussionmentioning

confidence: 99%

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Reactions of Sulphate Radicals with Substituted Pyridines: A Structure–Reactivity Correlation Analysis

et al. 2007

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“…7) or react with hydroxyl radicals generated by water oxidation to form peroxomonophosphoric acid (Eq. 8) [2,39,41,42].…”

Section: Voltammetric Studymentioning

confidence: 99%

“…Peroxophosphates have a wide variety of applications in areas such as oxidations in organic synthesis [1,2], cosmetics [3,4], agriculture [5], wastewater treatment [6], and also as bleaching agents in the detergent industry [7,8]. Recently, the reaction mechanisms of these compounds have been studied and several synthesis routes have been proposed [9]-some of which are electrochemical.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

et al. 2007

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID : 3043 Abstract A new method for the synthesis of peroxomonophosphate, based on the use of boron-doped diamond electrodes, is described. The amount of oxidant electrogenerated depends on the characteristics of the supporting media (pH and solute concentration) and on the operating conditions (temperature and current density). Results show that the pH, between values of 1 and 5, does not influence either the electrosynthesis of peroxomonophosphate or the chemical stability of the oxidant generated. Conversely, low temperatures are required during the electrosynthesis process to minimize the thermal decomposition of peroxomonophosphate and to guarantee significant oxidant concentration. In addition, a marked influence of both the current density and the initial substrate is observed. This observation can be explained in terms of the contribution of hydroxyl radicals in the oxidation mechanisms that occur on diamond surfaces. In the assays carried out below the water oxidation potential, the generation of hydroxyl radicals did not take place. In these cases, peroxomonophosphate generation occurs through a direct electron transfer and, therefore, at these low current densities lower concentrations are obtained. On the other hand, at higher potentials both direct and hydroxyl radical-mediated mechanisms contribute to the oxidant generation and the process is more efficient. In the same way, the contribution of hydroxyl radicals may also help to explain the significant influence of the substrate concentration. Thus, the coexistence of both phosphate and hydroxyl radicals is required to ensure the generation of significant amounts of peroxomonophosphoric acid.

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Production of Strong Oxidizing Substances with BDD Anodes

Sánchez-Carretero

Sáez

Cañizares

et al. 2011

Synthetic Diamond Films

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Reactions of Phosphate Radicals with Monosubstituted Benzenes. A Mechanistic Investigation

Cited by 29 publications

References 32 publications

Reactions of Sulphate Radicals with Substituted Pyridines: A Structure–Reactivity Correlation Analysis

Reactions of Sulphate Radicals with Substituted Pyridines: A Structure–Reactivity Correlation Analysis

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

Production of Strong Oxidizing Substances with BDD Anodes

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