title: Solvent influence on model oxidations of alpha-tocopherol.
abstract: (+/-)-alpha-Tocopherol has been oxidised with t-butyl hydroperoxide in chloroform in order to simulate in vivo oxidations due to lipid hydroperoxides. t-Butyl hydroperoxide proved to be a weak oxidant and failed to oxidise alpha-tocopherol in 3 h at 60 degrees C. Inclusion of a small amount of ethanol in the reaction mixture brought about immediate oxidation and the formation of a new product, 5-ethoxymethyl-7,8-dimethyltocol in addition to the spiro dimer and spiro trimer of alpha-tocopherol, alpha-tocopherylquinone and 5-formyl-7,8-dimethyltocol. Formation of 5-ethoxymethyl-7,8-dimethyltocol increased with increasing concentrations of ethanol, up to a maximum of 59% at 20% ethanol. Further increase in ethanol concentration brought about a decrease in the oxidation of alpha-tocopherol and in the formation of 5-ethoxymethyl-7,8-dimethyltocol. Oxidation of the tocopherol model compound 2,2,5,7,8-pentamethyl-6-hydroxychroman under similar conditions produced the analogous product, 5-ethoxymethyl-2,2,7,8-tetramethyl-6-hydroxychroman together with 5-formyl-2,2,7,8-tetramethyl-6-hydroxychroman and 2-(3'-hydroxy-3'-methylbutyl)-3,5,6-trimethylbenzo-1,4-quinone.
mesh_terms: D002384:Catalysis; D002725:Chloroform; D000431:Ethanol; D007536:Isomerism; D008054:Lipid Peroxides; D010084:Oxidation-Reduction; D010545:Peroxides; D011809:Quinones; D012997:Solvents; D014810:Vitamin E; D020122:tert-Butylhydroperoxide
chemical_list: D008054:Lipid Peroxides; D010545:Peroxides; D011809:Quinones; D012997:Solvents; D014810:Vitamin E; D000431:Ethanol; D002725:Chloroform; D020122:tert-Butylhydroperoxide