Direct Syntheses of Amides From Long-Chained Aliphatic Amines

An examination has been made of direct procedures for the synthesis of amides. Dodecylamine, tetradecylamine, hexadecylamine and octadecylamine have been treated with a variety of aliphatic and aromatic acids. Direct heating of the amine and acid, in open containers and at elevated temperatures, gave quite satisfactory yields of amides. This direct procedure has been resolved into two stages. First, a mixture of amine and acid, dissolved or suspended in warm petroleum ether, gives promptly and in good yield the corresponding salt. These salts can be used for the characterization of amine and acid. Second, when the salts are heated they are converted to the amides. As an example, n-octadecyl amine and acetic acid gives a 94 per cent yield of salt melting at 84.5-85°. Upon heating this salt at 225° for fifteen minutes there is a quantitative conversion to n-octadecylacetamide (m.p., 78-78.5°)