TRANSFORMATION OF FATTY-ACID HYDROPEROXIDES BY ALKALI AND CHARACTERIZATION OF PRODUCTS

It has previously been determined that (13S,9Z,11E)-13-hydroperoxy-9,1 1-octadecadienoic acid was mainly converted into (13S,9Z,11E)-13-hydro xy-9,11-octadecadienoic acid by 5 N KOH with preservation of the stere ochemistry of the reactant [Simpson, T.D., and Gardner, H.W. (1993) Li pids 28, 325-330]. In addition, about 20-25% of the reactant was conve rted into several unknown by-products. In the present work it was conf irmed that the stereochemistry was conserved during the hydroperoxy-di ene to hydroxydiene transformation, but also, novel by-products were i dentified. It was found that after only 40 min reaction (9Z)-13-oxo-tr ans-11,12-epoxy-9-octadecenoic acid accumulated to as much as 7% of th e total. Later, (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid bega n to disappear, and several other compounds continued to increase in y ield. Two of these compounds, 2-butyl-3,5-tetradecadienedioic acid and 2-butyl-4-hydroxy-5-tetradecenedioic acid, were shown to originate fr om (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid, and they accumul ated up to 2-3% each after 4 to 6 h. Some other lesser products includ ed 11-hydroxy-9,12-heptadecadienoic acid, 3-hydroxy-4-tridecenedioic a cid, 13-oxo-9,11-octadecadienoic acid and 12,13-epoxy-11-hydroxy-9-oct adecenoic acid. Except for the latter two, most or all of the compound s could have originated from Favorskii rearrangement of the early prod uct, (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid, through a cycl opropanone intermediate.