A possible role for singlet oxygen in the initiation of fatty acid autoxidation

Henry R Rawls, P. J. Van Santen

Research output: Contribution to journalArticlepeer-review

256 Scopus citations


A mechanism for the initiation of autoxidation in fatty acids is proposed which involves singlet state oxygen, formed through a photosensitization reaction, as the reactive intermediate. Both singlet oxygen generated in a radio-frequency gasdischarge, and photosensitization by natural pigments, were shown to catalyze the oxidation of methyl linoleate. The involvement of singlet oxygen was shown by the identification of nonconjugated hydroperoxides as products common to both photooxidation and singlet O2 oxidation. Nonconjugated hydroperoxides could not be detected among the free radical autoxidation products. Further proof for the above mechanism was gained by showing that compounds known to react strongly with singlet oxygen, inhibited the photooxidation. With the exception of chlorophyll, all sensitizers could be completely inhibited. Although singlet oxygen formation can account for approximately 80% of the observed chlorophyll photooxidation, at least one other mechanism must be involved. It is postulated that proton abstraction by the photoactivated carbonyl group of chorophyll could account for the remaining 20% of the observed photooxidation. The conclusion is drawn that oxygen, excited to its singlet state by a photosensitization process, plays the important role of forming the original hydroperoxides whose presence is necessary before the normal free radical autoxidation process can begin.

Original languageEnglish (US)
Pages (from-to)121-125
Number of pages5
JournalJournal of the American Oil Chemists Society
Issue number4
StatePublished - 1970
Externally publishedYes

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Organic Chemistry


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