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Thermal degradation of single methyl oleate hydroperoxides obtained by Photosensitized oxidation
Author(s) -
Lercker Giovanni,
Bortolomeazzi Renzo,
Pizzale Lorena
Publication year - 1998
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-998-0299-x
Subject(s) - singlet oxygen , chemistry , allylic rearrangement , degradation (telecommunications) , oxygen , photochemistry , thermal oxidation , gas chromatography , mass spectrometry , carbon fibers , singlet state , chromatography , reaction mechanism , catalysis , organic chemistry , excited state , materials science , telecommunications , physics , computer science , silicon , composite number , nuclear physics , composite material
A peroxidation mixture containing methyl 9‐ and 10‐hydroperoxy‐trans‐octadecenoates (MOHP) was obtained by singlet oxygen oxidation of methyl oleate. The two hydroperoxides were collected by solid phase extraction and purified separately by high‐performance liquid chromatography. Identification and single‐isomer purity evaluations were carried out by comparing the chromatographic and gas chromatography‐mass spectrometry parameters of the corresponding reduced hydroxy derivatives. Each purified MOHP was thermally degraded and new reaction mechanisms were proposed from the identification of the degradation products. Thermal rearrangement of each hydroperoxide isomer involved an allylic 3‐carbon intermediate before further degradation steps. The two MOHP isomers obtained from singlet oxygen oxidation produced all eight hydroperoxide isomers by thermal degradation in the condensed phase at high temperature (200°C). This result supports the assumption of singlet oxygen as a promoter of the first steps of oxidation of food lipids and also reconsiders the Khan mechanism.