Azide

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An azide is a N₃^- anion, or a reactive group in organic chemistry where a carbon substituent is attached as RN₃. The azido group is the corresponding N_{3</sup> organic functional group.}

Contents 1 Azide anion 2 Organic azides 3 Safety in the Handling of Sodium Azide and other Azides 4 External links 5 References

Azide anion

The anion's structure is:

N^-=N⁺=N^-

with a net charge of -1. Some azide salts are very explosive when heated or shaken, such as sodium azide (NaN₃) which is used in airbags. The azide anion is toxic, inhibiting the function of cytochrome c oxidase by binding irreversibly to the heme cofactor, in a process similar to that of carbon monoxide. Lead azide is another explosive inorganic azide compound.

Organic azides

Organic azides engage in useful organic reactions. They are relatively stable substituents, and act as electrophiles on the terminal nitrogen (usually liberating nitrogen after cycloreversion reactions), and have electron-donating character for the neighboring carbon. An Azide can easily expulse diatomic nitrogen, a property which is exploited in many reactions such as the Staudinger Ligation or the Curtius rearrangement or for example in the synthesis of γ-imino-β-enamino esters Template:Ref. In the Azide alkyne Huisgen cycloaddition azides react as 1,3-dipoles.

Image:Iminoenaminoester.gif

Safety in the Handling of Sodium Azide and other Azides

• Sodium azide is toxic (LD50 oral (rats)=27 mg/kg) and can be absorbed through the skin.
• Sodium azide decomposes explosively upon heating to above 275°C (hence its use in airbags in the automotive industry).
• Sodium azide reacts vigorously with CS2, bromine, nitric acid, dimethyl sulfate, and a series of heavy metals, including copper and lead.
• In reaction with water or Brønsted acids the highly toxic and explosive hydrogen azide is released.
• It has been reported that sodium azide and polymer-bound azide reagents react with dichloromethane and chloroform to form di- and triazidomethane resp., which are both unstable in high concentrations in solution. Various devastating explosions were reported while reaction mixtures were being concentrated on a rotary evaporator. The hazards of diazidomethane (and triazidomethane) have been well documented by A. Hassner et al. Template:Ref.
• Heavy-metal azides that are highly explosive under pressure or shock 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. Some organic and other covalent azides are classified as highly explosive and toxic (inorganic azides as neurotoxins; azide ions as cytochrome c oxidase (COX) inhibitors).
• Solid iodoazide is explosive and should not be prepared in the absence of solvent. Template:Ref.

External links

• http://www.azides.org

References

• Review: S. Bräse, C. Gil, K. Knepper, V. Zimmermann, Angew. Chem. 2005, 117, 5320-5374; Angew. Chem. Int. Ed. 2005, 44, 5188-5240.

Template:Note An efficient synthesis of γ-imino- and γ-amino-β-enamino esters Sven Mangelinckx, Pieter Van Vooren, David De Clerck, Ferenc Fülöp, and Norbert De Kimpea Arkivoc JC-1560E 2005 Online Article

Template:Note A. Hassner et al., Angew. Chem. Int. Ed. Engl., 25, 479 (1986), J. Org. Chem., 55, 2304 (1990).

Template:Note L. Marinescu, J. Thinggaard, I. B. Thomsen, M. Bols, J. Org. Chem. 2003, 68, 9453 – 9455.

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