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Reaction of α‐tocopherol in heated bulk phase in the presence of methyl linoleate (13 S )‐hydroperoxide or methyl linoleate
Author(s) -
Yamauchi Ryo,
Goto Kumiko,
Kato Koji
Publication year - 1998
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-998-0182-1
Subject(s) - methyl oleate , tocopherol , clinical chemistry , chemistry , lipidology , organic chemistry , antioxidant , catalysis , biochemistry , vitamin e
α‐Tocopherol and methyl (9 Z , 11 E )‐( S )‐13‐hydroperoxy‐9, 11‐octadecadienoate (13‐MeLOOH) were allowed to stand at 100°C in bulk phase. The products were isolated and identified as methyl 13‐hydroxyoctadecadienoate ( 1 ), stereoisomers of methyl 9,11,13‐octadecatrienoate ( 2 ), methyl 13‐oxo‐9, 11‐octadecadienoate ( 3 ), epoxy dimers of methyl linoleate with an ether bond ( 4 ), a mixture of methyl ( E )‐12, 13‐epoxy‐9‐(α‐tocopheroxy)‐10‐octadecenoates and methyl ( E )‐12, 13‐epoxy‐9‐(α‐tocopheroxy)‐11‐(α‐tocopheroxy)‐9‐octadecenoates ( 5 ), a mixture of methyl 9‐(α‐tocopheroxy)‐10,12‐octadecadienoates and methyl 13‐(α‐tocopheroxy)‐9, 11‐octadecadienoates ( 6 ), α‐tocopherol spirodiene dimer ( 7 ), and α‐tocopherol trimer ( 8 ). α‐Tocopherol and 13‐MeLOOH were dissolved in methyl myristate, and the thermal decomposition rate and the distributions of reaction products formed from α‐tocopherol and 13‐MeLOOH were analyzed. α‐Tocopherol disappeared during the first 20 min, and the main products of α‐tocopherol were 5 and 6 with the accumulation of 1–4 which were the products of 13‐MeLOOH. The results indicate that the alkyl and alkoxyl radicals from the thermal decomposition of 13‐MeLOOH could be trapped by α‐tocopherol to produce 5 and 6 . The reaction products of α‐tocopherol during the thermal oxidation of methyl linoleate were compounds 6 and 7 . Since the radical flux during the autoxidation might be low, the excess α‐tocopheroxyl radical reacted with each other to form 7 .