Synthesis and rearrangement of hydrazidic azides

Abstract

Hydrazidic azides have been synthesised by the reaction of hydrazidic halides with azide ion. The azides could not be converted into the isomeric tetrazoles under a variety of conditions. An earlier claim that the corresponding tetrazoles are products of the reaction of hydrazidines with nitrous acid must be regarded with doubt. On treatment with trifluoroacetic acid, or in acetic–sulphuric acid, hydrazidic azides rearrange to semicarbazides. In trifluoroacetic acid, both trifluoroacetyl semicarbazide and the parent semicarbazide are isolated, and the variation in yield with the nature of the hydrazidic azide has been investigated. We have also demonstrated, by use of an optically active hydrazidic azide substrate, that the migrating group in the azide rearrangement retains its configuration.