Nitric oxide reduction— mechanism

Figs. 3 and 4 show the X-ray diffraction profiles of the ACFs/Cu catalysts before and after catalytic reactions, respectively. The copper metal (Cu), which the difftaction patterns revealed around 26 43 and 50° on ACFs/Cu, is oxidized to CU2O (26 36 and 42) during No catalytic reduction process. The surftices of ACFs/Cu catalyst are found to scavenge the oxygen released by catalytic reduction of NO, which can be explained by the presence of another nitric oxide reduction mechanism between ACFs and ACFs/Cu catalysts. 

Shiro, Y., M. Fujii, T. lizuka, S.I. Adachi, K. Tsukamoto, K. Nakahara, and H. Shoun (1995). Spectroscopic and kinetic studies on reaction of cytochrome P450nor with nitric oxide. Implication for its nitric oxide reduction mechanism. J. Biol. Chem. 270, 1617-1623. 

The nitric oxide reduction of Cu(dmp)2(H20)2+ in aqueous media gives a Cu(II)-NO complex via an inner-sphere mechanism [216] (dmp = 2,9-dimethyl-l,10-phen-... 

Fox, J. B., and Ackerman, S. A. (1968). Formation of nitric oxide myoglobin Mechanisms of the reaction with various reductants. J. Food Set. 33, 364-370. 

Pearsall, K. A., and Bonner, F. T. (1982). Aqueous nitrosyliron(ll) chemistry. 2. Kinetics and mechanism of nitric oxide reduction. The denitrosyl complex. Inorg. Chem. 21, 1978-1985. 

De Soete, G. G. "Mechanisms of Nitric Oxide Reduction on Coal and Char Particles," Report on EERC Subcontract No. 8318-6, (Internal Report Institut Francais du Petrole, Ref. No. 28136), 1980. 

Effect of Hydrogen on Nitric Oxide Reduction by Char. The first series of experiments were carried out to investigate the material balances which reflect the reaction mechanism. 

MECHANISMS OF THE CARBON MONOXIDE OXIDATION AND NITRIC OXIDE REDUCTION REACTIONS OVER SINGLE CRYSTAL AND SUPPORTED RHODIUM CATALYSTS ... 

Mechanisms of the Carbon Monoxide Oxidation and Nitric Oxide Reduction Reactions over Single Crystal and Supported Rhodium Catalysts High Pressure Rates Explained using Ultrahigh Vacuum Surface Science", G.B. Fischer, Se H. Oh, J.E. Carpenter, C.L. DiMaggio, S.J. Schmieg,... 

C. Nitric Oxide Reduction, Oxidation, and Mechanisms of Nitrosation... 

Silaghi-Dumitrescu, R. (2003). Nitric oxide reduction by heme-thiolate enzymes (P450nor) A reevaluation of the mechanism. Eur. J. Inorg. Chem. 6, 1048-1052. 

A relationship between polyol pathway activity and reduction in endothelium-dependent relaxation in aorta from chronic STZ-diabetic rats has recently been reported (Cameron and Cotter, 1992). In agreement with several previous studies (Oyama et al., 1986 Kamata et al., 1989), endothelial-dependent relaxation was defective in the diabetic rats but the deficit was prevented by prior treatment with an AR inhibitor. The mechanism underlying the defect has been speculated to be due to decreased production of endothelium-derived relaxing factor (EDRF) or nitric oxide, NO (Hattori et al., 1991). It has been speculated that these vascular abnormalities may lead to diminished blood flow in susceptible tissues and contribute to the development of some diabetic complications. NO is synthesized from the amino-acid L-arginine by a calcium-dependent NO synthase, which requires NADPH as a cofactor. Competition for NADPH from the polyol pathway would take place during times of sustained hyperglycaemia and... 

Frank, B., Emig, G. and Renken, A. (1998) Kinetics and mechanism of the reduction of nitric oxides by H, under lean-burn conditions on a Pt-Mo-Co/a-ARO, catalyst, Appl. Catal. B 19, 45. 

The book focuses on three main themes catalyst preparation and activation, reaction mechanism, and process-related topics. A panel of expert contributors discusses synthesis of catalysts, carbon nanomaterials, nitric oxide calcinations, the influence of carbon, catalytic performance issues, chelating agents, and Cu and alkali promoters. They also explore Co/silica catalysts, thermodynamic control, the Two Alpha model, co-feeding experiments, internal diffusion limitations. Fe-LTFT selectivity, and the effect of co-fed water. Lastly, the book examines cross-flow filtration, kinetic studies, reduction of CO emissions, syncrude, and low-temperature water-gas shift. 

At present, new developments challenge previous ideas concerning the role of nitric oxide in oxidative processes. The capacity of nitric oxide to oxidize substrates by a one-electron transfer mechanism was supported by the suggestion that its reduction potential is positive and relatively high. However, recent determinations based on the combination of quantum mechanical calculations, cyclic voltammetry, and chemical experiments suggest that °(NO/ NO-) = —0.8 0.2 V [56]. This new value of the NO reduction potential apparently denies the possibility for NO to react as a one-electron oxidant with biomolecules. However, it should be noted that such reactions are described in several studies. Thus, Sharpe and Cooper [57] showed that nitric oxide oxidized ferrocytochrome c to ferricytochrome c to form nitroxyl anion. These authors also proposed that the nitroxyl anion formed subsequently reacted with dioxygen, yielding peroxynitrite. If it is true, then Reactions (24) and (25) may represent a new pathway of peroxynitrite formation in mitochondria without the participation of superoxide. 

Despite intense study of the chemical reactivity of the inorganic NO donor SNP with a number of electrophiles and nucleophiles (in particular thiols), the mechanism of NO release from this drug also remains incompletely understood. In biological systems, both enzymatic and non-enzymatic pathways appear to be involved [28]. Nitric oxide release is thought to be preceded by a one-electron reduction step followed by release of cyanide, and an inner-sphere charge transfer reaction between the ni-trosonium ion (NO+) and the ferrous iron (Fe2+). Upon addition of SNP to tissues, formation of iron nitrosyl complexes, which are in equilibrium with S-nitrosothiols, has been observed. A membrane-bound enzyme may be involved in the generation of NO from SNP in vascular tissue [35], but the exact nature of this reducing activity is unknown. 

Nitric acid synthesis, platinum-group metal catalysts in, 19 621 Nitric acid wet spinning process, 11 189 Nitric oxide (NO), 13 791-792. See also Nitrogen oxides (NOJ affinity for ruthenium, 19 638—639 air pollutant, 1 789, 796 cardioprotection role, 5 188 catalyst poison, 5 257t chemistry of, 13 443—444 control of, 26 691—692 effect on ozone depletion, 17 785 mechanism of action in muscle cells, 5 109, 112-113 oxidation of, 17 181 in photochemical smog, 1 789, 790 reduction with catalytic aerogels, l 763t, 764... 

The formation of S-nitroso thiols (R -S-N=0) is partly understood. A hypothetical mechanism is the reduction of A-oxosulfinamide derivatives (9.21, Fig. 9.4), but nothing appears to be known about such a possibility. What has been demonstrated is that nitric oxide by itself does not react with thiols to form 5-nitroso thiols, but does so in the presence of 02. Detailed kinetic analyses led to the mechanism summarized by Eqns. 9.1-9.3 [44] [45], In these and the following reactions, thiols are written as R -SH in consistency with Figs. 9.4 and 9.5. 

N. V. Gorbunov, A. N. Osipov, B. W. Day, B. Zayas-Rivera, V. E. Kagan, N. M. Elsayed, Reduction of Ferrylmyoglobin and Ferrylhemoglobin by Nitric Oxide A Protective Mechanism against Ferryl Hemoprotein-Induced Oxidations , Biochemistry 1995, 34, 6689-6699. 

A less common reactive species is the Fe peroxo anion expected from two-electron reduction of O2 at a hemoprotein iron atom (Fig. 14, structure A). Protonation of this intermediate would yield the Fe —OOH precursor (Fig. 14, structure B) of the ferryl species. However, it is now clear that the Fe peroxo anion can directly react as a nucleophile with highly electrophilic substrates such as aldehydes. Addition of the peroxo anion to the aldehyde, followed by homolytic scission of the dioxygen bond, is now accepted as the mechanism for the carbon-carbon bond cleavage reactions catalyzed by several cytochrome P450 enzymes, including aromatase, lanosterol 14-demethylase, and sterol 17-lyase (133). A similar nucleophilic addition of the Fe peroxo anion to a carbon-nitrogen double bond has been invoked in the mechanism of the nitric oxide synthases (133). 

Smits, R. H. H. and Iwasawa, Y. Reaction mechanisms for the reduction of nitric oxide by hydrocarbons on Cu-ZSM-5 and related catalysts. Appl Catal, B Environmental,... 

It was found that the electrocatalytic activity strongly depends on the nature of the electrode it decreases in the order Rh > Ru > Ir > Pd and Pt for the transition-metal electrodes and in the order Cu > Ag > Au for the coinage metals. It was concluded that the rate-determining step on Ru, Rh, Ir, Pt, Cu, and Ag is the reduction of nitrate to nitrite. It was assumed that chemisorbed nitric oxide is the key surface intermediate in the nitrate reduction. It was suggested that ammonia and hydroxylamine are the main products on transition-metal electrodes. This is in agreement with the known mechanism for NO reduction, which forms N2O or N2 only if NO is present in the solution. On Cu the production of gaseous NO was found, which was explained by the weaker binding of NO to Cu as compared to the transition metals. 

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