Nitrogen compounds Curtius rearrangement

Like diazoketones, acyl azides lose nitrogen when heated or irradiated. The end result is an isocyanate, formed either directly from the acyl aade, in a reaction called the Curtius rearrangement after Theodore Curtius (1857-1928), or by intramolecular rearrangement of a nitrene, which is the nitrogen analogue of a carbene (Fig. 18.70). For most acyl azides, it is known that the isocyanate is formed by direct rearrangement of the acyl compound and that the nitrene, though also formed from the azide, is not involved in isocyanate production. 

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