Kinetics of the reaction by which natural vitamin E is regenerated by vitamin C.
The rate constant and activation energy of the regeneration reaction of natural vitamin E by vitamin C were determined with a double-mixing stopped-flow spectrophotometer. The formation of vitamin C radical was observed in the absorption spectrum. The kinetic effect of methyl substitution on the aromatic ring of vitamin E radical indicates that partial charge-transfer plays a role in the reaction. Since a substantial deuterium kinetic isotope effect was not found, the tunneling effect may not play an important role under the present experimental conditions.
Nagaoka
Shin-ichi
S
Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan. nagaoka@ehimegw.dpc.ehime-u.ac.jp
Kakiuchi
Takuhiro
T
Ohara
Keishi
K
Mukai
Kazuo
K
D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D014810:Vitamin E / Q000737:chemistry*
D000975:Antioxidants; D005609:Free Radicals; D014810:Vitamin E; D001205:Ascorbic Acid