Nitric oxide reaction mechanism

Studies related to the mechanisms of nitric oxide reactions with transition metal complexes in this laboratory were supported by grants from the U.S. National Science Foundation, by a Collaborative UC/Los Alamos National Laboratory Research grant, by a grant from the U.S. Japan Cooperative Research Program (Photoconversion/ Photosynthesis) (NSF INT 9116346), and by a grant from the ACS Petroleum Research Fund. We thank the students and postdoctoral fellows at UC Santa Barbara who participated in this research and acknowledge collaborative studies with Dr. David Wink (National Cancer Institute, Bethesda MD, USA), Dr. Mikio Hoshino (RIKEN, Wako-shi, Japan) and Dr. Jon Schoonover (Los Alamos National Laboratory). 

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. 

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. 

In the absence of adequate kinetic data, these proposed reaction sequences are speculative in nature and will not be dignified by the term reaction mechanism. The sequences proposed Will be found valuable in both correlating many nitric oxide reaction and in suggesting additional experiments. 

Regardless of the exact reaction mechanism, these results suggest that the biological half-life of nitric oxide per se would be shortened by ONOO". On the other hand, if the net effect of the ONOO"/nitric oxide reaction was to increase the yield of nitrosothiol, it is conceivable that the biological effects of nitric oxide could be prolonged. 

Analysis of products from the reaction of phenol with nitric oxide, ONOO", or both (added simultaneously) provides some insight into possible reaction mechanisms as well as products that might be formed in vivo from phenolics such as tyrosine. Based on the apparent stoichiometry of the ONOO /nitric oxide reaction (see Fig. 2), a series of reactions were carried out in which ONOO was added at three different concentrations (0.2, 0.4, and 0.8 mM) in the absence and presence of a fixed concentration of nitric oxide (0.2 mM) added simultaneously. Ratios were chosen which would allow nitric oxide to remain in excess (0.2 mM ONOO" plus 0.2 mM nitric oxide), at stoichiometric concentrations (0.4 mM ONOO" plus 0.2 mM nitric oxide), and where ONOO" was in excess (0.8 mM ONOO" plus... 

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 vanadium and manganese complexes are the least stable and least studied of the series. The compound V(NO)(CO)5, a violet solid, is made by the action of nitric oxide on vanadium carbonyl (42), while Mn(NO)-(CO)4, a red liquid freezing at -1.5° C, is best made by treating Mn2(CO)g-(PPh3)2 with nitric oxide. The mechanism of this reaction has been briefly... 

Absorption of Nitrogen Oxides. There have been numerous studies and reports on the reaction mechanisms and rate-controlling steps for the absorption of nitrogen oxides into water (43—46). The overall reaction to form nitric acid may be represented by equation 14, where Ai/298 K kJ/mol ofNO consumed. 

Physical properties of hexachloroethane are Hsted in Table 11. Hexachloroethane is thermally cracked in the gaseous phase at 400—500°C to give tetrachloroethylene, carbon tetrachloride, and chlorine (140). The thermal decomposition may occur by means of radical-chain mechanism involving -C,C1 -C1, or CCl radicals. The decomposition is inhibited by traces of nitric oxide. Powdered 2inc reacts violentiy with hexachloroethane in alcohoHc solutions to give the metal chloride and tetrachloroethylene aluminum gives a less violent reaction (141). Hexachloroethane is unreactive with aqueous alkali and acid at moderate temperatures. However, when heated with soHd caustic above 200°C or with alcohoHc alkaHs at 100°C, decomposition to oxaHc acid takes place. 

G. Fisher and co-workers, "Mechanism of the Nitric Oxide—Carbon Monoxide—Oxygen Reaction Over a Single Crystal Rhodium Catalyst," in M. 

As the equilibrium concentration of N2O2 decreases rapidly with increase in temperature the decrease in rate is explained. However alternative mechanisms have also been suggested. ° l Nitric oxide reacts with the halogens to give XNO (p. 441). Some other facile reactions are listed below ... 

To illustrate this situation, consider the reaction between nitric oxide and chlorine, which is believed to proceed by a two-step mechanism ... 

Another redox reaction leading to arenediazonium salts was described by Morkov-nik et al. (1988). They showed that the perchlorates of the cation-radicals of 4-A,A-dimethylamino- and 4-morpholinoaniline (2.63) react with gaseous nitric oxide in acetone in a closed vessel. The characteristic red coloration of these cation-radical salts (Michaelis and Granick, 1943) disappears within 20 min., and after addition of ether the diazonium perchlorate is obtained in 84% and 92% yields, respectively. This reaction (Scheme 2-39) is important in the context of the mechanism of diazotization by the classical method (see Sec. 3.1). 

This statement does not mean, however, that the mechanism of diazotization was completely elucidated with that breakthrough. More recently it was possible to test the hypothesis that, in the reaction between the nitrosyl ion and an aromatic amine, a radical cation and the nitric oxide radical (NO ) are first formed by a one-electron transfer from the amine to NO+. Stability considerations imply that such a primary step is feasible, because NO is a stable radical and an aromatic amine will form a radical cation relatively easily, especially if electron-donating substituents are present. As discussed briefly in Section 2.6, Morkovnik et al. (1988) found that the radical cations of 4-dimethylamino- and 4-7V-morpholinoaniline form the corresponding diazonium ions with the nitric oxide radical (Scheme 2-39). 

Considerable support exists for Reaction 18a (35). The application of an electrostatic field during radiolysis of ethylene-nitric oxide (I.P. 9.25 e.v.) mixtures showed no enhancement of the butene yields, consistent with an ionic mechanism. When mixtures of C2D4 and C2H4 are irradiated in the presence of nitric oxide, product butene consists almost entirely of C4H8, C4D4H4, and C4D8—evidence for a molecular association mechanism. 

Derive a rate expression that is consistent with this mechanism. Treacy and Daniels [J. Am. Chem. Soc., 11 (2033), 1955] have determined that the orders of the reaction with respect to oxygen and nitric oxide are one and two, respectively, at high pressures and less than one and greater than two at low pressures. Is the proposed mechanism consistent with this data ... 

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. 

Reaction Mechanisms of Nitric Oxide with Biologically Relevant Metal Centers Peter C. Ford, Leroy E. Laverman and Ivan M. Lorkovic... 

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