Reactions of Some Tocopherols with the Methyl Radical

Abstract

The reactivity of some tocopherols (vitamin E) with the methyl radical was examined. When the methyl radical was generated from dimethyl sulfoxide by the action of hydrogen peroxide in the presence of ferrous sulfate, either β-tocopherol or γ-tocopherol reacted with it to give the corresponding methyl ether and 2, 5, 5, 7, 8-pentamethyl-2-(4, 8, 12-trimethyltridecyl) chroman-6 (5H)-one in Iow yields. Tocol afforded only a small amount of its methyl ether. On the other hand, 5, 7-dimethyltocol was converted to its methyl ether and 2, 5, 5, 7-tetramethyl-2-(4, 8, 12-trimethyltridecyl) chroman-6 (5H)-one in 9 and 38% yields, respectively. Taken with the previous data on α-tocopherol, these results indicate that the radical scavenging abilities of tocopherols against the methyl radical are in the following order : α-tocopherol≥5, 7-dimethyltocol>β-tocopherol=γ-tocopherol≥tocol.