AUTOXIDATION OF THE FURAN FATTY-ACID ESTER, METHYL 9,12-EPOXYOCTADECA-9,11-DIENOATE

The objective of this study was to identify autoxidation products of m ethyl 9,12-epoxyoctadeca-9,11-dienoate (F-9,F-12) Previous work has sh own that F-9,F-12 is a product both of autoxidation and singlet oxygen oxidation of the methyl ester derivative of conjugated linoleic acid (CLA). F-9,F-12, 95% pure, was synthesized from methyl ricinoleate. Th e synthetic F9,12 was heated at 50 degrees C in sealed tubes containin g air. Each tube contained 6 mg F-9,F-12 and 1 mg methyl stearate as a n internal standard. Samples were taken at 4.5, 7, 23, 46.5, 69.5, and 93 h. The oxidized F-9,F-12 was dissolved in isooctane and analyzed b y gas chromatography (GC), CC-direct deposition-Fourier transform infr ared spectroscopy, and CC-electron ionization mass spectrometry. CLA m ethyl ester was oxidized in a similar manner. Under these conditions, the half-lives of CLA and Fs,12 were 40 and 35 h, respectively. Oxidat ion products of F9,12 that were identified included: 5-hexyl-2-furalde hyde (1), methyl 8-oxooctanoate (II), methyl 13-oxo-9,12-epoxytrideca- 9,11-dienoate (III), methyl 8-oxo-9,12-epoxy-9,11-octadecadienoate (IV ), and methyl 13-oxo-9,1 2-epoxy-9,11-octadecadienoate (V).