Vv. Chudinova et al., PREPARATIVE SEPARATION AND H-1-NMR IDENTI FICATION OF PRODUCTS OF LINOLEIC-ACID AUTOOXIDATION, Bioorganiceskaa himia, 21(7), 1995, pp. 545-553
Bulk phase oxidation of linoleic acid in a diffuse system in the dark
at 2 - 5 degrees C was found to produce three types of oxygenated deri
vatives. An effective method of HPLC on the nitrile phase was develope
d for the analysis and preparative isolation of products, which made i
t possible to prepare individual structural isomers of each type. Afte
r preliminary identification by chemical, chromatographic, and UV spec
troscopic methods, the isolated compounds were identified as 9- and 13
-isomers of hydroperoxy-, hydroxy-, and ketooctadecadienoic acids with
Z-E-conjugated double bond systems. The formation of minor E-E-regioi
somers of linoleic acid hydroperoxides was also observed. The assignme
nt of signals in the H-1 NMR spectra of the compounds isolated, includ
ing homonuclear proton-decoupled spectra, validated the proposed struc
tures. It is suggested that the preferable formation of Z-E-isomers of
oxygenated products in the process of linoleic acid autooxidation tin
der low temperature is connected with impossibility of overcoming the
energy barrier of primary peroxyradical isomerization.