Curtius Reaction Mechanism

About Curtius Rearrangement and Reaction

Curtius rearrangement involves the decomposition of acyl azides in an inert solvent (e.g., chloroform, benzene, etc.,) by gentle heat to isocyanate. Good yields of isocyanates have been obtained.

If the reaction is carried out in alcoholic or aqueous medium, the isocyanate further reacts to form urethane, amine or substituted urea.

Reaction Mechanism of Curtius Reaction 

The mechanism of the rearrangement is very similar to Hofmann's rearrangement to isocyanate. The driving force of the rearrangement is the electron-deficient nitrogen formed on elimination of nitrogen molecule on heating. Since there Is no evidence for the formation of nitrene, all the steps may be concerted.

Applications of Curtius Reaction 

This simple one-step and mild reaction afford an important and easy preparative method for primary amines,-a ·amino acids, aldehydes, urethanes, etc. Preparation of. Primary amines-Primary amines, free from secondary and tertiary amines can be prepared, e.g.,