Phenyl nitrene reaction with oxygen

Observation of triplet (4-nitro)phenyl nitrene in solution enables performance of experiments designed to estimate its rate of reaction. Two such processes were extensively investigated the combination with oxygen and its addition to 2-methylnitrosopropane that gives the mixed azoxy compound. Unfortunately, in both cases overlapping absorptions prohibit direct interpretation of the results. Nevertheless, upper limits to the rate constants for these reactions were obtained. Triplet (4-nitro)phenyl nitrene combines with oxygen or the nitrosopropane with a bimolecular rate constant that is less than approximately 2xl05M 1s-1 a value about 105 times below the... 

When the triplet is an excited state, energy transfer occurs to form singlet oxygen. Ground state triplets react with oxygen by a spin-allowed process which, for carbenes in particular, produce carbonyl oxides [64], It seems that triplet nitrenes react with oxygen slowly. This will be discussed more fully later. Here we examine the products formed from reaction of photolysis of phenyl azide in the presence of oxygen. 

The generation and reactions of arylnitrenes continue to attract attention. Evidence for a photoinitiated autocatalytic chain mechanism in the photodecomposition of phenyl azide has been reported, and the reaction of photochemically generated phenyl nitrene with oxygen has been reexamined. Irradiation of p-azidoaniline in aqueous solution yields triplet p-aminophenyl nitrene, which on reaction with water is converted into the highly reactive p-benzoquinone diimine. Both m- and p-nitrophenyl azides, on photoelimination of nitrogen at 77 K, afford the corresponding nitrenes, whereas o-nitrophenyl azide (93) is converted without the intermediacy of a nitrene into the benzofurazan (94). 4,4 -... 

Table 5. jS-Amino Esters and y-Phenyl Carbonyl Compounds by Ring-Opening Reactions of Oxygen-Substituted Cyclopropanes with Nitrenes and Carbenes... 

Reaction of Phenyl Nitrene with O2. The reaction of phenyl nitrene with oxygen warrants special consideration because it reveals an unusual feature of the triplet state. In general, triplet species react with oxygen rapidly [64],... 

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