Isolation and structural determination of the C₂₀ and C₂₂ unsaturated fatty acids of rapeseed oil

Polyunsaturated C 20 and C 22 fatty acids, which seldom are found in the triglycerides of higher plants, were isolated from rapeseed oil and their structures fully characterized. Pure 20∶2 and 20∶3 were identified as all‐ cis Δ‐11,14 and all‐ cis Δ‐11,14,17. Pure 22∶2 and 22∶3 were characterized as all‐ cis Δ‐13,16 and all‐ cis Δ‐13,16,19. Trienoic acids were found in very small amounts. Reinvestigation of the 20∶1 acid showed that it is a mixture of 75% cis Δ‐11 and 25% cis Δ‐13, whereas the 22∶1 is the cis Δ‐13 isomer only. Evidence is also given for the presence of a 24∶1 acid.