Phenyl azide is an organic compound with the formula C₆H₅N₃. It is one of the prototypical organic azides. It is a pale yellow oily liquid with a pungent odor. The structure consists of a linear

azide In chemistry, azide is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant applic ...

substituent bound to a

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...

group. The C−N=N angle is approximately 120°.

Preparation

Phenyl azide is prepared by the

diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General propert ...

phenylhydrazine Phenylhydrazine is the chemical compound with the formula . It is often abbreviated as . It is also found in edible mushrooms. Properties Phenylhydrazine forms monoclinic prisms that melt to an oil around room temperature which may turn yellow ...

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 ...

: :C₆H₅NHNH₂ + HNO₂ → C₆H₅N₃ + 2 H₂O Aryl iodides bearing electron-withdrawing substituents undergo metathesis with sodium azide in the presence of Cu(I),

sodium ascorbate Sodium ascorbate is one of a number of mineral salts of ascorbic acid (vitamin C). The molecular formula of this chemical compound is C6H7NaO6. As the sodium salt of ascorbic acid, it is known as a mineral ascorbate. It has not been demonstrate ...

, and N,N'-dimethylethane-1,2-diamine (DMEDA): :RC₆H₄I + NaN₃ → RC₆H₄N₃ + NaI It can also be prepared by condensation of benzenediazonium salt with toluenesulfonamide, followed by hydrolysis.

Chemical reactions

Phenyl azide cycloadds to alkenes and especially

alkynes \ce \ce Acetylene \ce \ce \ce Propyne \ce \ce \ce \ce 1-Butyne In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no ...

, particularly those bearing electronegative substituents. In a classic example of

click chemistry In chemical synthesis, click chemistry is a class of biocompatible small molecule reactions commonly used in bioconjugation, allowing the joining of substrates of choice with specific biomolecules. Click chemistry is not a single specific reaction ...

, phenyl azide and

phenylacetylene Phenylacetylene is an alkyne hydrocarbon containing a phenyl group. It exists as a colorless, viscous liquid. In research, it is sometimes used as an analog for acetylene; being a liquid, it is easier to handle than acetylene gas. Preparation I ...

react to give diphenyl

triazole A triazole is a heterocyclic compound featuring a five-membered ring of two carbon atoms and three nitrogen atoms with molecular formula C2H3N3. Triazoles exhibit substantial isomerism, depending on the positioning of the nitrogen atoms within t ...

. Phenyl azide reacts with

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 ...

to give the Staudinger reagent

triphenylphosphine phenylimide Triphenylphosphine phenylimide is the organophosphorus compound with the formula Ph3P=NPh ( Ph = C6H5). It is a white solid that is soluble in organic solvents. The compound is a prototype of a large class of Staudinger reagents, resulting from ...

(C₆H₅NP(C₆H₅)₃).

Thermolysis Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is req ...

induces loss of N₂ to give the highly reactive phenylnitrene C₆H₅N.W. H. Pearson, P. S. Ramamoorthyin "Phenyl Azide" Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. .

Safety

As with many other azides, phenyl azide poses a risk of explosion, so a protective blast shield is recommended during purification and handling. Distillations are hazardous. ''

Organic Syntheses ''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and ex ...

'' recommends a vacuum of 5mm Hg to give a boiling point of "66–68 °C/21 mm. with a bath temperature of 70–75 °C." The pure substance may be stored in the dark, cold, and even then the shelf-life is only weeks.

References

{{reflist Phenyl compounds IARC Group 3 carcinogens Organoazides