Azide

Azide is the anion with the formula N−3. It is the conjugate base of hydrazoic acid (HN3). N−3 is a linear anion that is isoelectronic with CO2, NCO−, N2O, NO+2 and NCF. Per valence bond theory, azide can be described by several resonance structures; an important one being N − = N + = N − {displaystyle {ce {^{-}N={overset {+}{N}}=N^{-}}}} . Azide is also a functional group in organic chemistry, RN3. Azide is the anion with the formula N−3. It is the conjugate base of hydrazoic acid (HN3). N−3 is a linear anion that is isoelectronic with CO2, NCO−, N2O, NO+2 and NCF. Per valence bond theory, azide can be described by several resonance structures; an important one being N − = N + = N − {displaystyle {ce {^{-}N={overset {+}{N}}=N^{-}}}} . Azide is also a functional group in organic chemistry, RN3. The dominant application of azides is as a propellant in air bags. Sodium azide is made industrially by the reaction of nitrous oxide, N2O with sodium amide in liquid ammonia as solvent: Many inorganic azides can be 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. An alternative route is direct reaction of the metal with silver azide dissolved in liquid ammonia. Some azides are produced by treating the carbonate salts with hydrazoic acid. The principal source of the azide moiety is 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: 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: A classic method for the synthesis of azides is the Dutt–Wormall reaction in which a diazonium salt reacts with a sulfonamide first to a diazoaminosulfinate and then on hydrolysis the azide and a sulfinic acid.