Nitrogen intermediates

Azides are known to undergo photoelimination of nitrogen to produce univalent nitrogen intermediates (nitrenes). These electron-deficient intermediates can then undergo a variety of intermolecular and intramolecular... 

Addition of phosphinomethyl spirophosphorane 260 to isocyanates and azides presumaby generates anionic nitrogen intermediates that cyclize with the phosphorane to give spirophosphoranides 96, 97, and 261 (Scheme 35) <1996PS493>. 

James, S.L. andGlaven, J., Macrophage cytotoxicity against schistosomula of Schistosoma mansoni involves arginine-dependent production of reactive nitrogen intermediates, J. Immunol., 143, 4208,1989. 

Malawista, S. E., Montgomery, R. R., Van Blaricom, G. (1992). Evidence for reactive nitrogen intermediates in killing of Staphylococci by human neutrophil cytoplasts A new microbicidal pathway for polymorphonuclear leukocytes. J. Clin. Invest. 90, 631-6. 

In fuel-rich systems, there is evidence [8, 22, 23] that the fuel-nitrogen intermediate reacts not only with oxidizing species in the manner represented, but also competitively with NO (or another nitrogen intermediate) to form N2. This second step, of course, is the reason that NO yields are lower in fuel-rich systems. The fraction of fuel nitrogen converted to NO in fuel-rich systems can be as much as an order of magnitude less than that of lean or near-stoichiometric systems. One should realize, however, that even in fuel-rich systems, the exhaust NO concentration is substantially greater than its equilibrium value at the combustion temperature. 

In fuel-rich systems, the conversion reactions of the fuel-nitrogen intermediates are subject to doubt, mainly because the normal oxidizing species 02,0, and OH are present only in very small concentrations, particularly near the end of the reaction zone. Haynes el al. [14] offer the interesting suggestion that the CN can be oxidized by C02 since the reaction... 

In the 1930s, Michaelis compared radical cations with trivalent-carbon or divalent-nitrogen intermediates using potentiometric methods. He rationalized their unusual stability as follows The fact that such radicals are capable of existence at all, can be attributed to a particular symmetry of structure resulting in resonance a... 

In their paper in 1987, Hibbs et al. (1987a) proposed that the characteristic pattern of metabolic dysfunction inflicted by CAMs is due to iron loss from aconitase and other iron-sulfur-containing enzymes resulting from nitrite or oxygenated nitrogen intermediates in the pathway of nitrite and nitrate synthesis. Much data have since been published to support this proposal, although as described below the chemical details of this process are still not clear. 

Reaction (46) removes the active nitrogen intermediate. Reaction (45) has also been postulated in a number of other studies which are discussed in Section VI-B-1. 

Carbenes are highly reactive, have short lifetimes, and undergo characteristic chemical changes, the most important of which are listed with examples in Table 5.7. Monovalent nitrogen intermediates (57), called nitrenes, are also known their chemistry is in many ways similar to that of carbenes.143... 

Bogdan, C., Rollinghoff, M. and Diefenbach, A. (2000) Reactive oxygen and reactive nitrogen intermediates in innate and specific immunity. Curr. Opin. Immunol., 12, 64-76. 

Studies on the reduction of N2 by the enzyme have only detected one nitrogenous intermediate [72,76,108], This intermediate is characterized by its ability to produce N2H4 upon acid or alkali quench. It was suggested that this N2H4 was derived from a hydrazido(2-) species on the basis of the observation in the chemical systems that this state represents a potential well in the formation of NH3 and because some isolated hydrazido(2-) complexes treated with either acid or alkali can produce N2H4. 

Remick, D. G. and Villarete, L. (1996) Regulation of cytokine gene expression by reative oxygen and reactive nitrogen intermediates. J. Leukoc. Biol. 59,471-475. 

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