Electron-transfer mechanism in radical-scavenging reactions by a vitamin E model in a protic medium

Ikuo Nakanishi, Tomonori Kawashima, Kei Ohkubo, Hideko Kanazawa, Keiko Inami, Masataka Mochizuki, Kiyoshi Fukuhara, Haruhiro Okuda, Toshihiko Ozawa, Shinobu Itoh, Shunichi Fukuzumi, Nobuo Ikota

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Abstract

The scavenging reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) or galvinoxyl radical (GO*) by a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), was significantly accelerated by the presence of Mg(ClO4)2 in de-aerated methanol (MeOH). Such an acceleration indicates that the radical-scavenging reaction of 1H in MeOH proceeds via an electron transfer from 1H to the radical, followed by a proton transfer, rather than the one-step hydrogen atom transfer which has been observed in acetonitrile (MeCN). A significant negative shift of the one-electron oxidation potential of 1H in MeOH (0.63 V vs. SCE), due to strong solvation as compared to that in MeCN (0.97 V vs. SCE), may result in change of the radical-scavenging mechanisms between protic and aprotic media.

Original languageEnglish
Pages (from-to)626-629
Number of pages4
JournalOrganic and Biomolecular Chemistry
Volume3
Issue number4
DOIs
Publication statusPublished - 2005 Feb 21

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ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)

Cite this

Nakanishi, I., Kawashima, T., Ohkubo, K., Kanazawa, H., Inami, K., Mochizuki, M., Fukuhara, K., Okuda, H., Ozawa, T., Itoh, S., Fukuzumi, S., & Ikota, N. (2005). Electron-transfer mechanism in radical-scavenging reactions by a vitamin E model in a protic medium. Organic and Biomolecular Chemistry, 3(4), 626-629. https://doi.org/10.1039/b416572a