Phenyl azide

Preparation

Phenyl azide is prepared by the diazotization of phenylhydrazine with nitrous acid: :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 (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, particularly those bearing electronegative substituents. In a classic example of click chemistry, phenyl azide and phenylacetylene react to give diphenyl triazole.

Phenyl azide reacts with triphenylphosphine to give the Staudinger reagent triphenylphosphine phenylimide (C6H5NP(C6H5)3).

Thermolysis induces loss of N2 to give the highly reactive phenylnitrene C6H5N.

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 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

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References

1. (2014). "Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book)". [[Royal Society of Chemistry.
2. (1864-01-01). "XX. On a new class of compounds in which nitrogen is substituted for hydrogen". Proceedings of the Royal Society of London.
3. Griess, Peter. (1866). "Ueber eine neue Klasse organischer Verbindungen, in denen Wasserstoff durch Stickstoff vertreten ist". Annalen der Chemie und Pharmacie.
4. R. O. Lindsay and C. F. H. Allen. (1942). "Phenyl azide".
5. Andersen, Jacob. (2005). "Rapid Synthesis of Aryl Azides from Aryl Halides under Mild Conditions". Synlett.
6. W. H. Pearson, P. S. Ramamoorthy, H. Y. Lo in "Phenyl Azide", ''Encyclopedia of Reagents for Organic Synthesis'' (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. {{doi. 10.1002/047084289X.rp049.pub2.