Curtius Reaction

a method of preparing primary amines from the azides of carboxylic acids:

Upon heating, the azide (I) decomposes with the formation of an intermediate particle—nitrene, or azine (II). The subsequent migration of the hydrocarbon radical R toward the nitrogen atom (Curtius rearrangement) yields an isocyanate (III). Isocyanates can be isolated during azide decomposition in inert solvents. Amine (V) is obtained as a result of the hydration of isocyanate and subsequent decarboxylation of the obtained carbamic acid (IV). The mechanism involved in the Curtius reaction is similar to the mechanism observed in the Hofmann and Lossen reactions. The Curtius reaction is used in laboratory organic synthesis. The German chemist T. Curtius first discovered the reaction in 1894.