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Laboratory of Organic Chemistry
Laboratory Info:Contact Information:Laboratory of Organic Chemistry Department of Chemistry University of Helsinki P.O. Box 55 FI-00014 UNIVERSITY OF HELSINKI |
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Fatty acid chemistry
Synthesis and modification Seppo Kaltia, Jorma Matikainen and Tapio Hase This research, originating from the study of tall oil fatty acids, has expanded into a more general research project involving the stereo controlled synthesis of polyenic fatty acids, their 1,5-sigmatropic hydrogen shift reactions, and intramolecular Diels-Alder reaction. Partly because of the structural similarities of pinolenic and linolenic acids and partly because of the biological and nutritional importance of the latter we have recently focused our isomerization and IMDA studies to linolenic acid. Our results show that structures analogous to cyclopinolenic acids are formed in minor amounts only and that other types of hexahydroindenoid structures are formed as the main products. (Kaltia, Matikainen, Hase) Our latest activity on this field is a novel simple and potentially large scale synthesis of pinolenic (5 Z ,9 Z ,12 Z -octadecatrienoic acid) and 12 Z ,15 Z - octadecadienoic acid methyl esters together with their careful NMR-analysis. New chemistry of linolenic acid Seppo Kaltia, Jorma Matikainen and Tapio Hase When linolenic acid methyl ester is heated with alkali and the product is subjected to further heating the following reactions seem to occur. Heat treatment of edible oils containing linolenic acid has been claimed to produce only trace amounts of bicyclic fatty acids, the main cyclic components being cyclohexadiene derivatives. In our hands, however, heat treatment of linolenic acid methyl ester, as shown above, leads to complex mixture of cyclic acids where hexahydroindenoic structures predominate. This prompts the question if hexahydroindenoic chemistry has been underestimated so far as regards the chemistry of frying oils. We are now examining this possibility by using rapeseed oil as the starting material. As for linolenic acid, our results show that the main conjugated isomers leading to the most abundant cyclolinolenic acids are 9 Z ,14 Z ,16 E - and 8 E ,10 E ,15 Z- octadecatrienoic acids. |
