Separation and Identification of Fatty Acids

For the characterization of fatty acids, 2, 4-dinitrophenylhydrazones of p-bromophenacyl esters of even-numbered saturated fatty acids from C₂ to C₂₀ and several unsaturated fatty acids from monoethenoid to triethenoid were prepared. The derivatives of linoleic and linolenic acids as well as those of the other unsaturated and saturated acids, were successfully obtained in crystalline forms which showed sharp and high melting points, 72° and 69°, respectively. It was found that the derivatives of unsaturated acids were valuable for characterizing the parent acids, while those of saturated acids were unsuitable for this purpose owing to the similarity of their melting points.