Kinetic study of the reaction between vitamin E radical and alkyl hydroperoxides in solution.
Kinetic study of the reaction between vitamin E radical and alkyl hydroperoxides has been performed, as a model for the reactions of lipid hydroperoxides with vitamin E radical in biological systems. The rates of reaction of hydroperoxides (n-butyl hydroperoxide 1, sec-butyl hydroperoxide 2, and tert-butyl hydroperoxide 3) with vitamin E radical (5,7-diisopropyl-tocopheroxyl 4) in benzene solution have been determined spectrophotometrically. The second-order rate constants, k-1, obtained are 1.34 x 10(-1) M-1s-1 for 1, 2.42 x 10(-1) M-1s-1 for 2, and 3.65 x 10(-1) M-1s-1 for 3 at 25.0 degrees C. The result indicates that the rate constants increase as the total electron donating capacity of the alkyl substituents at alpha-carbon atom of hydroperoxides increases. The above rates, k-1, are about seven order of magnitude lower than those, k1, for the reaction of vitamin E with peroxyl radical.
Department of Chemistry, Faculty of Science, Ehime University, Matsuyama, Japan.
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Mukai
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Kohno
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Ishizu
D000478:Alkylation; D055598:Chemical Phenomena; D002621:Chemistry; D005609:Free Radicals; D006861:Hydrogen Peroxide; D007700:Kinetics; D012996:Solutions; D014810:Vitamin E
D005609:Free Radicals; D012996:Solutions; D014810:Vitamin E; D006861:Hydrogen Peroxide