Purification of long‐chain saturated fatty acids by recrystallization of their molecular compounds with acetamide

Summary A method is described for the purification of lauric, myristic, palmitic, and stearic acid, based upon the recrystallization of the fatty acid‐acetamide molecular compounds and subsequent regeneration of the acid by extraction of the acetamide with water. The choice of the crystallization solvent is rather critical because of the marked difference in the solubility characteristics of the acetamide and the fatty acids. For the purification of lauric and myristic acids acetone or a one‐to‐one benzene‐acetone mixture by volume proved to be the best solvents, and for palmitic and stearic acids the most satisfactory results were obtained with either benzene or a two‐to‐one mixture by volume of benzene and acetone. Since the molecular compounds must be crystallized from concentrated solutions, the separation of the crystals from the mother liquor must be made by centrifugation. The recrystallized fatty acid‐acetamide compounds provide a convenient intermediate for the preparation of pure acid amides free from homologs.