Benzoyl azide, $\mathrm{C}{}_6\mathrm{H}{}_5-\mathrm{CO}-\mathrm{N}{}_3$, is heated in dry ethanol until nitrogen evolution stops. The main organic product is

Heating the acyl azide expels $\mathrm{N}{}_2$ with simultaneous migration of phenyl from carbon to nitrogen (Curtius rearrangement), giving phenyl isocyanate, $\mathrm{C}{}_6\mathrm{H}{}_5-\mathrm{N}=\mathrm{C}=\mathrm{O}$. In dry ethanol the alcohol adds to the isocyanate, giving the carbamate. Aniline would form only after hydrolysis with water.