Phenyl azide

Phenylazide is an organic compound with the formula C₆H₅N₃. It is one of the prototypical organic azides. It has a pungent odor.

It is prepared by the diazotization of phenylhydrazine with nitrous acid:^[1]

C₆H₅NHNH₂ + HNO₂ → C₆H₅N₃ + 2 H₂O

The structure consists of a linear N=N=N substituent bound to a phenyl group. The C-N=N angle is approximately 120°.

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Chemical reactions

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]

Other fundamental phenyl-N molecules

Related phenyl-N building blocks include C₆H₅NH₂, C₆H₅NO, C₆H₅NO₂, C₆H₅NHOH, C₆H₅NHNH₂, and C₆H₅N_2⁺.

Safety

A protective blast shield is needed during purification and handling. Distillation temperatures should be as low a possible. Organic Syntheses recommends 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

1. ^ R. O. Lindsay; C. F. H. Allen. "Phenyl Azide" Organic Syntheses, Collected Volume 3, page 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.