937377-44-1Relevant articles and documents
Vitamin E chemistry. studies into initial oxidation intermediates of α-tocopherol: Disproving the involvement of 5a-C-centered "chromanol methide" radicals
Rosenau, Thomas,Kloser, Elisabeth,Gille, Lars,Mazzini, Francesco,Netscher, Thomas
, p. 3268 - 3281 (2008/02/04)
(Chemical Equation Presented) Contrary to concepts handed down in the literature from the early days of vitamin E research, one-electron oxidation of vitamin E does not involve 5a-C-centered radicals. A combined approach of analytical techniques, in particular electron paramagnetic resonance spectroscopy (EPR), organic synthesis of special derivatives, isotopic labeling, kinetic studies, and computational chemistry was used to re-evaluate the one-electron and two-electron oxidation chemistry of α-tocopherol (α-toc). EPR in combination with 5a-13C-labeled compounds provided no indication of the involvement of 5a-C-centered radicals. Oxidation of special tocopherol derivatives were used to disprove the occurrence of 5a-C-centered one-electron intermediates. Additionally it was shown that those vitamin E reactions that were commonly evoked to plead for the involvement of C-centered tocopheryl radicals actually proceeded via heterolytic, i.e., non-radical, intermediates. The results will help to clear widely spread misunderstandings about the chemistry of vitamin E and will have mechanistic implications for the synthesis of tocopherol-based supramolecular structures and 5a-substituted α-tocopherol derivatives.
