Promoting Effect of Cyanamide on Dehydrative Condensation in Amide Synthesis

Abstract

Cyanamide was found to promote effectively the condensation reaction of primary amines with carboxylic acids in an appropriate solvent such as diethyl ketone at its refluxing temperature to give the corresponding amides. To investigate the promoting effect of cyanamide, the condensation rates of aniline with benzoic acid under various conditions have been determined by GLC. The facile condensation was promoted by the use of a large excess of both cyanamide and benzoic acid versus aniline and depended on the reaction temperature rather than the nature of the solvent. On the basis of the yields of the substituted benzanilides prepared from substituted anilines and substituted benzoic acids, it was also found that the electron-releasing substituent attached on the amine and the electronwithdrawing one on the carboxylic acid accelerated the condensation. From these results, a reaction mechanism is discussed.