ガスクロマトグラフィーによる南氷洋産鯨油の研究 (第4報)

シロナガスクジラ骨油中の分枝鎖脂肪酸の分析

抄録

The author reports in the present paper the separation and tentative identification of non-ureacomplex-forming multibranched-chain fatty acids as well as urea-complex-forming branched-chain ones of the iso, anteiso and of other series.
Blue whale bone oil was deacidified with a 20%-potassium hydroxide solution in n-hexane, followed by purification through a silicic acid column. The methyl esters, obtained by alkali-catalyzed methanolysis of the refined oil, were separated by silicic acid column chromatography and ureacomplex fractionation. Each fraction was then analyzed by gas-liquid chromatography (GLC) on a polyester (PEGA) column before and after hydrogenation.
In order to separate the urea-complex-forming branched-chain fatty acids, some urea-complex-forming fractions separated as mentioned above were converted into isopropyl esters by a BF₃isopropyl alcohol reagent. The purified isopropyl esters and their hydrogenated products were separated by urea-complex fractionation. These fractions were analyzed by thin-layer, GLC and infrared spectrometry.
Isopropyl esters of the branched-chain fatty acid concentrated in the non-urea-complex-forming fractions were saponified to the free acids.
The infrared absorption spectrum of thus fractionated fatty acids suggested the existence of an isopropyl group as a doublet at near 1380 cm^-1, and consequently the presence of branched-chain fatty acids was corroborated. The branched-chain fatty acids having “fractional carbon numbers (FCN)” of 0.2, 0.4, 0.6 and 0.8 on the PEGA column were found in the isopropyl ester of nonurea-complex-forming fraction.
The last two were tentatively identified to be iso and anteiso acids, respectively, according to the published data.
In addition, the component of ECL value 17.5 in the multibranched-chain fatty acid fraction was presumed as phytanic acid (3, 7, 11, 15-tetramethylhexadecanoic acid) after comparison with dihydrophytol acetate synthesized from phytol.