Some physical,chemical, and biological properties of natural and synthetic unsaturated C18 acids

Series of octadecenoic (cis andtrans), octadecynoic, octadecadienoic (cis,cis andtrans,trans), and octadecadiynoic acids have been synthesized and employed in a comparative study of some physical (melting point, Raman spectra, NMR spectra, Ag⁺ thin layer chromatography, and gas liquid chromatography) and biological properties. The results show that the position of unsaturation has a considerable influence on the physical and biological properties of isomeric unsaturated acids. Several chemical reactions of linoleic acid and of the related oxygenated acids ricinoleic or vernolic (12,13-epoxyoleic) furnish cyclopropane compounds and 1,4- (or 1,5-) epoxides. The formation of these is rationalized in terms of neighboring group participation. The oxymercuration-demercuration reaction is the basis of a new method of examining acids with Δ3, Δ4, or Δ5 unsaturation. F.D. Gunstone received the 1973 Award in Lipid Chemistry at the AOCS 47th Annual Fall Meeting, Chicago, September 1973. This Award Address was presented at the Plenary Session.