Oxidation of nitric oxide

Oxidation of Nitric Oxide. Nitric oxide [10102 3-9] reacts slowly with oxygen to yield nitrogen dioxide [10102 4-0] according to the reversible reaction (eq. 12) for which A 7/295 —57kJ/mol of NO consumed (13.6 kcal/mol). 

The oxidation of nitric oxide, NO, is a reaction involved in smog production. It is moderately rapid at normal temperatures. The oxidation of methane, CHt (household gas), however, occurs so slowly at room temperature that we may say that, for all practical purposes it doesn t react at all. Again, the difference in the reaction rates must depend upon specific characteristics of the reactants, NO and CH,. 

Consider the oxidation of nitric oxide, NO, to nitrogen dioxide, NOi ... 

Tsukahara, H., Ishida, T., and Mitsufumi, M., Gas-phase oxidation of nitric oxide chemical kinetics and rate constant, Nitric Oxide, 3, 191-198 (1999). 

N. Diab and W. Schuhmann, Electropolymerized manganese porphyrin/polypyrrole films as catalytic surfaces for the oxidation of nitric oxide. Electrochim. Acta 47, 265-273 (2001). 

N. Diab, J. Oni, A. Schulte, I. Radtke, A. Blochl, and W. Schuhmann, Pyrrole functionalised metallo-porphyrins as electrocatalysts for the oxidation of nitric oxide. Talanta 61, 43-51 (2003). 

E. Casero, F. Pariente, and E. Lorenzo, Electrocatalytic oxidation of nitric oxide at indium hexacyanof-errate film-modified electrodes. Anal. Bioanal. Chem. 375, 294—299 (2003). 

The most important physiological nitrogen substrate of peroxidases is undoubtedly nitric oxide. In 1996, Ishiropoulos et al. [252] suggested that nitric oxide is able to interact with HRP Compounds I and II. Glover et al. [253] measured the rate constants for the reactions of NO with HRP Compounds I and II (Table 22.2) and proposed that these reactions may occur in in vivo inflammatory processes. The interaction of NO with peroxidases may proceed by two ways through the NO one-electron oxidation or the formation of peroxidase NO complexes. One-electron oxidation of nitric oxide will yield nitrosonium cation NO+ [253,254], which is extremely unstable and rapidly hydrolyzed to nitrite. On the other hand, in the presence of high concentrations of nitric oxide and the competitor ligand Cl, the formation of peroxidase NO complexes becomes more favorable. It has been shown [255]... 

Rate of reaction depends on temperature and usually increases nearly exponentially as temperature increases. An important exception is the oxidation of nitric oxide, which is involved in the manufacture of nitric acid in this case, the rate decreases as T increases. 

The oxidation of nitric oxide, NO(A) + 02 - NO2, is a third-order gas-phase reaction (second-order with respect to NO). Data of Ashmore et al. (1962) for values of the rate constant at various temperatures are as follows ... 

Reactions 2-6 through 2-8 form a catalytic cycle, in that the hydroxyl radical that is used in Reaction 2-6 is r enerated in Reaction 2-8. The net results of this cycle are the oxidations of nitric oxide to nitrogen dioxide and carbon monoxide to carbon dioxide by the oxygen present in the air. 

The participation of hydroxyl and hydroperoxy radicals in the oxidation of nitric oxide raises the possibility that these radicals might also attack hydrocarbons. In the case of hydroxyl these reactions are known to be fairly rapid. On the basis of e rate constants that have been measured and estimates of those which have not the rates of attack of hydroxyl and hydroperoxy radicals appear to be large enough to explain the excess consumption of propylene shown in Figure 2-5. 

Although the above reactions generate a few fi radicals, most of the oxidation of nitric oxide to nitrogen dioxide is carried out by the alkyl-peroxy, RO, and hydroperoxy radicals that are formed in later reactions involving reactive hydrocarbons, aldehydes, or even carbon monoxide. One such example is shown in Figure 2-7. There is still considerable uncertainty as to the mechanism of these secondary reactions. The modeling studies should be consulted for details. ... 

The above reaction is rapid and shifts almost fiiUy to the product side. (2) oxidation of nitric oxide to form nitrogen dioxide ... 

Nitrogen tetroxide always is formed along with nitrogen dioxide during preparation of the dioxide (See Nitrogen Dioxide.) Mixed oxides are produced by oxidation of nitric oxide (NO) in air, heating metal nitrates, or by metals reacting with nitric acids or nitrates. 

Figure 2. Specific activities of the rare-earth oxides in the oxidation of nitric oxide...

Detailed and fundamental studies of the mechanistic aspects of the electrochemical reduction and oxidation of nitric oxide were carried out by the Eindhoven group [82, 83] on a series of metals (Pt, Pd, Rh, Ru, Ir, and Au) both in the case of polycrystalline and well-defined single-crystal surfaces. It was found that the reduction process at all metals studied shows a high selectivity with respect to N2O production at high potentials while at low potentials the formation of NH3 is the dominant... 

Cheng, L., E. Peake, D. Rogers, and A. Davis, Oxidation of Nitric Oxide Controlled by Turbulent Mixing in Plumes from Oil Sands Extraction Plants, Atmos. Enriron., 20, 1697-1703 (1986). 

Ignarro, L. J., Fukuto, J. M., Griscavage, J. M., Rogers, N. E., and Burns, R. E. (1993). Oxidation of nitric oxide in aqueous solution to nitrite but not nitrate Comparison with enzymatically formed nitric oxide from L-arginine. Proc. Nad. Acad. Sci. U.S.A. 90, 8103-8107. 

Metallic NPs are most widely used in catalytic applications due to their inherent properties. Several examples of platinum and gold NPs are apparent in the literature. For example, electrodeposited platinum NPs on porous carbon substrates exhibit electrocatalytic activity for the oxidation of methanol.60 In another example, gold NPs catalyze the electrochemical oxidation of nitric oxide on modified electrodes.61 In general, catalytic NPs provide two distinct functions enhancing an electrochemical reaction and/or increasing electron transfer to an electrode. 

The reaction between nitric oxide and hydrogen is interesting because it takes place at much higher temperatures than the other three termolecular reactions. Its speed at 1,100° absol. is more or less comparable with that of the oxidation of nitric oxide at the ordinary... 

In polluted urban atmospheres, singlet molecular oxygen may play an essential part in the oxidation of nitric oxide to nitrogen dioxide.5,6 The... 

It is now important to see whether singlet molecular oxygen can take part in any processes which cause oxidation of nitric oxide to nitrogen dioxide. The direct reaction... 

Ashmore, Burnett, and Tyler9 studied the oxidation of nitric oxide over the temperature range 104-506°C. They found that nitrogen did not affect the rate. In their experiments, NO, 02, and Na pressures were in the range 2-100, 25-600, and 0-570 torr, respectively. Their data agreed within 10% with those of Bodenstein and his co-workers. 

Smith387 studied the rate of oxidation of nitric oxide by nitric acid in the gas phase in the temperature range 263-363°K. The overall reaction was... 

One method of determining the values of the exponents in a rate law is to carry out a series of experiments in which the initial rate of a reaction is measured as a function of different sets of initial concentrations. Consider, for example, the air oxidation of nitric oxide, one of the reactions that contributes to the formation of acid rain ... 

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