Phenyl azide

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Phenyl azide
Skeletal formula Ball-and-stick model
Identifiers
CAS number 622-37-7
PubChem 69319
ChemSpider 62529
EC number 210-730-3
MeSH C014747
Jmol-3D images Image 1
Properties
Molecular formula C6H5N3
Molar mass 119.12 g mol−1
Appearance Pale yellow, oily liquid
Boiling point 49–50 °C at 5 mmHg
Solubility in water not appreciable
Hazards
Main hazards explosive
Related compounds
Related compounds Aniline
Nitrobenzene
Nitrosobenzene
Phenylhydrazine
Phenylhydroxylamine
Diazonium cation
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Phenylazide is an organic compound with the formula C6H5N3. It is one of the prototypical organic azides. It has a pungent odor. The structure consists of a linear azide substituent bound to a phenyl group. The C-N=N angle is approximately 120°.

Preparation[edit]

Phenyl azide is prepared by the diazotization of phenylhydrazine with nitrous acid:[1]

C6H5NHNH2 + HNO2 → C6H5N3 + 2 H2O

Aryl iodides bearing electron-withdrawing substituents undergo metathesis with sodium azide in the presence of Cu(I), sodium ascorbate, and N,N'-dimethylethane-1,2-diamine (DMEA):

RC6H4I + NaN3 → RC6H4N3 + NaI

Chemical reactions[edit]

C6H5N3 is used to make heterocycles via cycloaddition to alkenes and especially alkynes, particularly those bearing electronegative substituents. It reacts with triphenylphosphine to give the Staudinger reagent C6H5NP(C6H5)3. Thermolysis induces loss of N2 to give the highly reactive phenylnitrene C6H5N.[2]

Phenyl azide and its analogues undergo the azide alkyne Huisgen cycloaddition, a classic example of click chemistry. For example phenyl azide and phenylacetylene give diphenyl triazole.

Safety[edit]

Because of the potential for explosion,[1] a protective blast shield is recommended during purification and handling. Distillation temperatures should be as low a possible. Organic Syntheses 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."[1] The pure substance may be stored in the dark, cold, and even then the shelf-life is only weeks.

References[edit]

  1. ^ a b c R. O. Lindsay and C. F. H. Allen (1955), "Phenyl azide", Org. Synth. ; Coll. Vol. 3: 710 
  2. ^ W. H. Pearson, P. S. Ramamoorthyin "Phenyl Azide" Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.