Transient absorption spectral evidence for phenyl nitrene as the chain propagator in the photo-initiated autocatalytic chain decomposition of phenyl azide and phenyl isocyanate

Abstract

Transient absorption spectra were recorded 15 ns to 6 μs following a 266 nm laser pulse for phenyl azide and for phenyl isocyanate in aerated acetonitrile and 3-methylpentane solutions. Transient spectra which are independent of concentration and of delay time, are essentially identical for phenyl azide and for phenyl isocyanate, except at higher energies where phenyl azide absorbs, and are assigned as that of triplet phenyl nitrene. Since there is no spectral evidence for a second species, phenyl nitrene is thought the chain propagator in the autocatalytic chain decomposition that occurs for phenyl azide and for phenyl isocyanate.