The fractionation of marine‐oil fatty acids with urea

Summary In two series of experiments, marine‐animal‐oil fatty acids were fractionated with urea using methanol as solvent. In the first series, menhaden‐oil fatty acids were fractionated at 1°C. Almost all the saturated and monoenoic fatty acids were removed at mole ratios of 12∶1 to 13∶1. At higher ratios increasing amounts of the less stable dienoic fatty acids were precipitated. By the use of the appropriate ratio, fractions having iodine values above 300 were prepared. In the second series, fatty acids from the oils of menhaden, herring, tuna, seal, salmon eggs, and salmon heads and viscera were fractionated at a mole ratio of urea to fatty acid of 9.2∶1. At 25° and 1° the complexes were composed almost entirely of saturated and monoenoic fatty acids, but as the temperature was lowered to −30°, the content of dienoic fatty acids in the precipitates increased.