Reactions of sulphate radicals with substituted pyridines: a structure–reactivity correlation analysis
The kinetics of the oxidation of pyridine, 3-chloropyridine, 3-cyanopyridine, 3-methoxypyridine and 3-methylpyridine mediated by SO₄<M>; radicals are studied by flash photolysis of peroxodisulphate, S₂O₈²⁻−, at pH 2.5 and 9. The absolute rate constants for the reactions of both, the basic and...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2007 |
| País: | Argentina |
| Institución: | Universidad Nacional de La Plata |
| Repositorio: | SEDICI (UNLP) |
| Idioma: | inglés |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/159380 |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/159380 |
| Access Level: | acceso abierto |
| Palabra clave: | Química kinetics oxidation pyridine flash photolysis |
| Sumario: | The kinetics of the oxidation of pyridine, 3-chloropyridine, 3-cyanopyridine, 3-methoxypyridine and 3-methylpyridine mediated by SO₄<M>; radicals are studied by flash photolysis of peroxodisulphate, S₂O₈²⁻−, 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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