The Photo-decomposition of 1-Azidopyrene in the Benzene Solution

Abstract 1-Nitrenopyrene (Py-N) was produced by the photo-decomposition of 1-azidopyrene (Py-N3) in the benzene solution at 77°K and at room temperature. At 77°K, Py-N was found to be stable, and its electronic absorption and ESR spectra were measured. The result shows that its ground state is triplet and the fine structure constant, D, is equal to 0.73 cm−1. At room temperature, 1-nitrenopyrene was found to be converted easily into 1,1′-trans-azopyrene (trans-Py-N=N–Py) in the oxygen-free benzene solution and into 1-nitropyrene (Py-NO2) in addition to Py-N=N-Py in the oxygen-containing benzene solution. The decay process of Py-N as a reaction intermediate and the formation processes of the reaction products were studied by the flash-photolysis technique, and from an analysis of the results, the rate constants at 23°C were determined to be 2.1×109lmol−1 sec−1 and 1.4×103sec−1 for 2Py–N→trans-Py-N=N–Py and for Py–N+O2→Py-NO2, respectively.