Azide

Source: Wikipedia, the free encyclopedia.
The azide anion
For organic azides, see organic azide.

In

air bags.[1]

Preparation

liquid ammonia as solvent:[2]

Many inorganic azides can be prepared directly or indirectly from sodium azide. For example,

lead nitrate and sodium azide. An alternative route is direct reaction of the metal with silver azide dissolved in liquid ammonia.[3] Some azides are produced by treating the carbonate salts with hydrazoic acid
.

Bonding

Azide is

resonance structures
; an important one being N−=N+=N−

Reactions

Azide salts can decompose with release of nitrogen gas. The decomposition temperatures of the alkali metal azides are: NaN3 (275 °C), KN3 (355 °C), RbN3 (395 °C), and CsN3 (390 °C). This method is used to produce ultrapure alkali metals:[4]

2 MN3 heat→ 2 M + 3 N2

Protonation of azide salts gives toxic hydrazoic acid in the presence of strong acids:

H+ + N−3 → HN3

Azide as a ligand forms numerous transition metal azide complexes. Some such compound are more shock sensitive.

Many inorganic covalent azides (e.g., chlorine, bromine, and iodine azides) have been described.[5]

The azide anion behaves as a nucleophile; it undergoes

conjugate addition to 1,4-unsaturated carbonyl compounds.[1]

Azides can be used as precursors of the metal nitrido complexes by being induced to release N2, generating a metal complex in unusual oxidation states (see high-valent iron).

Disposal

Azides decompose with nitrite compounds such as sodium nitrite when acidified. This is a method of destroying residual azides, prior to disposal.[6] In the process, nitrogen, nitrogen oxides, and hydroxides are formed:

3 N−3 + NO−2 + 2 H2O → 5 N2 + 4 OH−
N−3 + 7 NO−2 + 4 H2O → 10 NO + 8 OH−

Applications

About 251 tons of azide-containing compounds are produced annually, the main product being sodium azide.[7] Sodium azide NaN3 is the propellant in automobile airbags. It decomposes on heating to give nitrogen gas, which is used to quickly expand the air bag:[7]

2 NaN3 → 2 Na + 3 N2

Heavy metal azides, such as

lead azide, Pb(N3)2, are shock-sensitive detonators which decompose to the corresponding metal and nitrogen, for example:[8]

Pb(N3)2 → Pb + 3 N2

Silver azide AgN3 and barium azide Ba(N3)2 are used similarly. Some organic azides are potential rocket propellants, an example being 2-dimethylaminoethylazide (DMAZ) (CH3)2NCH2CH2N3.

Safety

Azides are

high explosives detonable when heated or shaken. Heavy-metal azides are formed when solutions of sodium azide or HN3 vapors come into contact with heavy metals or their salts. Heavy-metal azides can accumulate under certain circumstances, for example, in metal pipelines and on the metal components of diverse equipment (rotary evaporators, freezedrying
equipment, cooling traps, water baths, waste pipes), and thus lead to violent explosions.

See also

References

  1. ^
    PMID 16100733
    .
  2. ISBN 978-0-08-037941-8
    .
  3. PMID 24924913
    .
  4. ^ Dönges, E. (1963). "Alkali Metals". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). NY: Academic Press. p. 475.
  5. doi:10.1002/anie.199505111
    .
  6. ISBN 0-309-05229-7.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  7. ^
    ISBN 3527306730
    .
  8. ^ Shriver; Atkins. Inorganic Chemistry (5th ed.). New York: W. H. Freeman and Company. p. 382.
  9. S2CID 252009657
    . Retrieved 18 September 2022.
  10. S2CID 240154010
    .

External links

Look up azide or azido- in Wiktionary, the free dictionary.
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