Kinetics and mechanism of the reaction of a nitroxide radical (tempol) with a phenolic antioxidant.
In the absence of redox-active transition metal ions, the removal of Tempol by Trolox occurs by a simple bimolecular reaction that, most probably, involves a hydrogen transfer from phenol to nitroxide. The specific rate constant of the process is small (0.1 M(-1) s(-1)). Metals can catalyze the process, as evidenced by the decrease in rate observed in the presence of diethylenetriaminepentaacetic acid (DTPA). Furthermore, addition of Fe(II) (20 microM ferrous sulfate and 40 microM EDTA) produces a noticeable increase in the rate of Tempol consumption.
Aliaga
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Faculty of Sciences, Department of Chemistry, University of Chile, Chile.
Lissi
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EA
Augusto
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Linares
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D000975:Antioxidants / Q000494:pharmacology*; D002839:Chromans / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003497:Cyclic N-Oxides / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology; D005609:Free Radicals / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D010100:Oxygen / Q000378:metabolism; D004369:Pentetic Acid / Q000494:pharmacology; D019800:Phenol / Q000737:chemistry*; D013113:Spin Labels; D013997:Time Factors
D000975:Antioxidants; D002839:Chromans; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D005609:Free Radicals; D013113:Spin Labels; D019800:Phenol; D004369:Pentetic Acid; D006859:Hydrogen; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D010100:Oxygen; C001803:tempol