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 methyl 9,12-epoxyoctadeca-9,11-dienoate (F_9,12). Previous work has shown that F_9,12 is a product both of autoxidation and singlet oxygen oxidation of the methyl ester derivative of conjugated linoleic acid (CLA). F_9,12, 95% pure, was synthesized from methyl ricinoleate. The synthetic F_9,12 was heated at 50°C in sealed tubes containing air. Each tube contained 6 mg F_9,12 and 1 mg methyl stearate as an internal standard. Samples were taken at 4.5, 7, 23, 46.5, 69.5, and 93 h. The oxidized F_9,12 was dissolved in isooctane and analyzed by gas chromatography (GC), GC-direct deposition-Fourier transform infrared spectroscopy, and GC-electron ionization mass spectrometry. CLA methyl ester was oxidized in a similar manner. Under these conditions, the half-lives of CLA and F_9,12 were 40 and 35 h, respectively. Oxidation products of F_9,12 that were identified included: 5-hexyl-2-furaldehyde ( I), 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-9,12-epoxy-9,11-octadecadienoate ( V). [ABSTRACT FROM AUTHOR]