Acyl azides are

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

derivatives with the general formula RCON₃. These compounds, which are a subclass of

organic azide An organic azide is an organic compound that contains an azide (–) functional group. Because of the hazards associated with their use, few azides are used commercially although they exhibit interesting reactivity for researchers. Low molecular w ...

s, are generally colorless.

Preparation

Typically acyl azides are generated under conditions where they rearrange to the isocyanate. Alkyl or aryl

acyl chloride In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...

s react with sodium azide to give acyl azides. : Preparation of acyl azides from acyl chlorides

The second major route to azides is from the acyl hydrazides with

nitrous acid Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in Solution (chemistry), solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazoni ...

. Acyl azides have also been synthesized from various carboxylic acids and sodium azide in presence of

triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists a ...

and

trichloroacetonitrile Trichloroacetonitrile is an organic compound with the formula CCl3CN. It is a colourless liquid, although commercial samples often are brownish. It is used commercially as a precursor to the fungicide etridiazole. It is prepared by dehydration o ...

catalysts Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

in excellent yields at mild conditions. Another route starts with aliphatic and aromatic

aldehydes In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

reacting with

iodine azide Iodine azide () is an explosive inorganic compound, which in ordinary conditions is a yellow solid. Formally, it is an inter-pseudohalogen. Preparation Iodine azide can be prepared from the reaction between silver azide and elemental iodine: ...

which is formed from sodium azide and

iodine monochloride Iodine monochloride is an interhalogen compound with the formula . It is a red-brown chemical compound that melts near room temperature. Because of the difference in the electronegativity of iodine and chlorine, this molecule is highly polar ...

in acetonitrile.

Uses

Curtius rearrangement The Curtius rearrangement (or Curtius reaction or Curtius degradation), first defined by Theodor Curtius in 1885, is the thermal decomposition of an acyl azide to an isocyanate with loss of nitrogen gas. The isocyanate then undergoes attack by a va ...

, acyl azides yield

isocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...

Acyl azides are also formed in Darapsky degradation, Degradación de Darapsky

Historical references

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References

{{reflist, 2 Functional groups