Stereoisomerism of 4-Alkenoic Acids (C10, C12 and C14) in the Fatty Acids from the Seed Oil of Litsea glauca Sieb.

Abstract

Decenoic, dodecenoic and tetradecenoic acid were separated in pure state from the seed oil of Litsea glauca Sieb. by means of silver nitrate silica gel chromatography. The position of the double bond at Δ 4 was determined in terms of the fact, that the resulting acids were succinic and the corresponding saturated C6-, C8- and C10-acid as described in Table 1, when methyl alkenoates were oxidized with KMnO4 according to Armstrong and Hilditch, and also in terms of their NMR spectra, which showed an apparent strong doublet at 7.65 γ and a multi plet centered at 4.57 γ. Presence of the broad absorptions centered at 720 cm-1 and absence of the absorptions at 965-970 cm-1 in the IR spectra of the acids, indicated in the above title, showed that their double bonds take the cis-configuration. The physical constants of the acids, indicated in the above title, their p-bromophenacyl esters and p-phenylphenacyl esters were compared with those of the trans-alkenoic acids of the same carbon atoms, which were previously prepared by M. Iwakiri and with those of the obtusilic, linderic and tsuzuic acid, which were separated from the seed oil of Lindera obtusiloba, Bl. by S. Komori and S. Ueno.