Preparation
The principal source of the azide moiety is sodium azide. Sodium azide is made industrially by the reaction of nitrous oxide, N2O with sodium amide, NaNH2, in liquid ammonia as solvent. The overall stoichiometry is given by
- N2O + 2NaNH2 → NaN3 + NaOH + NH3
Most inorganic and organic azides are prepared directly or indirectly from sodium azide. For example, lead azide, used in detonators, may be prepared from the metathesis reaction between lead nitrate and sodium azide. As a pseudohalogen compound, sodium azide generally displaces an appropriate leaving group (e.g. Br, I, OTs) to give the azido compound.
Aryl azides may be prepared by displacement of the appropriate diazonium salt with sodium azide, or trimethylsilyl azide; nucleophilic aromatic substitution is also possible, even with chlorides. Anilines and aromatic hydrazines undergo diazotization, as do alkyl amines and hydrazines.
Appropriately functionalized aliphatic compounds undergo nucleophilic substitution with sodium azide. Aliphatic alcohols give azides via a variant of the Mitsunobu reaction, with the use of hydrazoic acid. Hydrazines may also form azides by reaction with sodium nitrite:
- PhNHNH2 → PhN3
Alkyl or aryl acyl chlorides react with sodium azide in aqueous solution to give acyl azides, which give isocyanates in the Curtius rearrangement.
The azo-transfer compounds, trifluoromethanesulfonyl azide and imidazole-1-sulfonyl azide, are prepared from sodium azide as well. They react with amines to give the corresponding azides:
- RNH2 → RN3
Read more about this topic: Azide
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