Photochemistry of Phenyl Azide: The Role of Singlet and Triplet Phenylnitrene as Transient Intermediates

The sequence of transient intermediates formed by the photolysis of phenyl azide (1) was determined by a combination of techniques including absorption, emission, and EPR spectroscopies as well as quantitative product analyses of irradiated glassy solutions at 77 K, in addition to kinetic and spectrographic flash photolysis at various temperatures. Several ortho, ortho’-disubstituted derivatives of 1 were also studied. The prevailing reaction pathway of 1 at ambient temperature is different from that at 77 K. The change of mechanism is traced to a temperature-dependent branching ratio from the primary photoproduct, singlet phenylnitrene (12). It is established that the photoproduct observed by absorption spectroscopy at 77 K is predominantly triplet phenylnitrene (12), as was originally postulated by Reiser et al. (Trans. Faraday Soc. 1966, 62, 3162–3169). © 1986, American Chemical Society. All rights reserved.

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