A possible decomposition product of oils containing unsaturated fatty acids with the double bond pattern 603,6,9 or 603,6,9, etc., is 2-trans,4-cis, 7-cis-decatrienal. It has therefore been investigated whether this trienal is present in strongly autoxidized linolenic acid, soybean, linseed and fish oils. Via a degassing technique the carbonyls from the samples of oils heated in a closed system under nitrogen were collected and separated as their 2,4-dinitrophenylhydrazones (DNPHs) by thin layer chromatography (TLC). The presence of 2-trans,4-cis,7-cis-decatrienal in the samples was positively established by TLC, UV absorption and mass spectroscopy of its DNPH. All analytical data established the complete identity of the isolated DNPH with a synthesized 2,4,7-decatrienal-DNPH. The free aldehyde obtained on hydrolysis of the alkatrienal-DNPH in question had the same flavor as authentic 2-trans,4-cis,7-cis-decatrienal, having a fish or rather a whale oil flavor.

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In connection with the study of autoxidation of some iso-linoleic acids, the 9, 15-, 8,15-, and 7,15-octadecadienoie acids have been synthesized by partial hydrogenation of the corresponding diynoie acids. These aeids were prepared by coupling o)-iodo-3-alkynes with ~-chloro-l-alkynes by means of sodium amide in liquid ammonia to form ,o-ehlorohexadi3nles, followed by condensation of the corresponding iodine compounds with sodium malonic ester.

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