Nitrit-Ion Oxidation

Step 2 represents the chain origin, step 3 is nitrite-ion oxidation, steps 4-6 are the chain propagation, and steps 8 and 10 show the chain termination at the expense of radical dimerization. Steps 4 and 5 can probably be nnited into one stage, as Scheme 4.38 points out. 

Since nitrite ions oxidize the iron atoms of hemoglobin and convert it to methemoglobin, there may be a loss in oxygen delivery to tissues. While methemoglobinemia does not follow therapeutic doses of organic nitrates, it can be observed after overdosage or accidental poisoning. 

PROBABLE FATE photolysis-, slow process, but might be only degradation process that occurs, atmospheric and aqueous photolytic half-life 13.7 days, in clear surface waters, half-life 2-14 days and faster if the water is acidic or contains nitrate or nitrite ions oxidation-. attack by hydroxyl radicals at C-2 and C-4 positions occurs, half-life 14 hrs, photooxidation half-life in water 21 days-5.6 yrs, photooxidation half-life in air 6 days hydrolysis slight possibility of hydrolysis to 1,4-benzoquinone after sorption by clay minerals volatilization not an important process sorption slight potential for irreversible sorption by clay minerals biological processes no bioaccumulation, resists biodegradation under natural conditions and inhibits microbial growth... 

Mechanism of toxicologic damage. Nitrite ion oxidizes the ferrous iron in hemoglobin to the ferric state, forming methemogbbin, which is incapable of oxygen transport... 

The carried out column test gave important results. It could be stated that the N, N-dichlorosulfonamide copolymer is a very effective and efficient nitrite ion oxidant. It was shown that its superiority over the competitive N-monochlorosulfonamide copolymer results not only from its higher active-chlorine content i. e. from its higher oxidation capacity and by the higher redox potential i.e. oxidative power. The N, N-dichlorosulfonamide copolymer placed in a column removed nitrites from the processed solution efficiently, without any mechanical or chemical disturbance. 

Oxidation. Nitroparaffins are resistant to oxidation. At ordinary temperatures, they are attacked only very slowly by strong oxidi2ing agents such as potassium permanganate, manganese dioxide, or lead peroxide. Nitronate salts, however, are oxidi2ed more easily. The salt of 2-nitropropane is converted to 2,3-dimethyl-2,3-dinitrobutane [3964-18-9], acetone, and nitrite ion by persulfates or electrolytic oxidation. With potassium permanganate, only acetone is recovered. 

Nucleophilic displacement of iodide by the nitrite ion in 1-iodo-17/. l//,2//,2W-perfluoroalkanes affords the 1-nitro analogue (equation 4). Oxidative nitration of the 1-mtro-l//, l//,2//.2//-perfluoroalkane with tetranitromethane yields the ge/n-dinitro compound [4. ... 

Little work has been carried out on the mechanism of inhibition of the corrosion. of copper in neutral solutions by anions. Inhibition occurs in solutions containing chromate , benzoate or nitrite ions. Chloride ions and sulphide ions act aggressively. There is evidence that chloride ions can be taken up into the cuprous oxide film on copper to replace oxide ions and create cuprous ion vacancies which permit easier diffusion of cuprous ions through the film, thus increasing the corrosion rate. 

Nitrite ion is often used in plutonium solvent extraction systems to oxidize Pu(III) to Pu(IV) and to reduce Pu(VI) to Pu(IV). But HONO, produced in HN03 media, is extractable into TBP-diluent systems and can interfere with subsequent reductive stripping of plutonium. There is thus a need to find a reagent comparable to nitrite ion in its reactions with Pu(III) and Pu(VI), but which does not extract into TBP solutions. 

Newton s second law, L0 nickel, 49, 665 nickel arsenide structure, 201 nickel surface, 189 nickel tetracarbonyl, 665 nickel-metal hydride cell, 520 NiMH cell, 520 nitrate ion, 69, 99 nitration, 745 nitric acid, 629 nitric oxide, 73, 629 oxidation, 549 nitride, 627 nitriding, 208 nitrite ion, 102 nitrogen, 120, 624 bonding in, 108 configuration, 35 photoelectron spectrum, 120... 

Indeed, given an improperly designed or understood system, a blocking agent, like ascorbic acid, could be catalytic toward nitrosamine formation. For example, if the source of nitrosatlng agent is nitrite ion and the susceptible amine is in the lipid phase, conceivably ascorbic acid could cause the rapid reduction of nitrite ion to nitric oxide which could migrate to the lipid phase. Subsequent oxidation of NO to NO in the lipid phase could cause nitrosation. 

It follows from the above that MPO may catalyze the formation of chlorinated products in media containing chloride ions. Recently, Hazen et al. [172] have shown that the same enzyme catalyzes lipid peroxidation and protein nitration in media containing physiologically relevant levels of nitrite ions. It was found that the interaction of activated monocytes with LDL in the presence of nitrite ions resulted in the nitration of apolipoprotein B-100 tyrosine residues and the generation of lipid peroxidation products 9-hydroxy-10,12-octadecadienoate and 9-hydroxy-10,12-octadecadienoic acid. In this case there might be two mechanisms of MPO catalytic activity. At low rates of nitric oxide flux, the process was inhibited by catalase and MPO inhibitors but not SOD, suggesting the MPO initiation. 

However, at high rates of nitric oxide flux, the formation of nitrated and oxidized products became insensitive to the presence of catalase or MPO inhibitors but increasingly inhibited by SOD, suggesting the participation of peroxynitrite. (It is interesting that Reaction (30) might be a one-electron reduction of hydrogen peroxide by nitrite ion. If such a process really takes... 

The NO reduction of the Cu(II) complex Cu(dmp)2(H20)2+ (dmp = 2,9-dimethyl-l,10-phenanthroline) to give Cu(dmp)2 plus nitrite ion (Eq. (20)) has been studied in aqueous solution and various mixed solvents (42a). The reduction potential for Cu(dmp)2(H20)2+ (0.58 V vs. NHE in water) (48) is substantially more positive than those for most cupric complexes owing to steric repulsion between the 2,9-methyl substituents that provide a bias toward the tetrahedral coordination of Cu(I). The less crowded bis(l,10-phenanthroline) complex Cu(phen)2(H20)2+ is a weaker oxidant (0.18 V) (48). 

Zhang, Z., Naughton, D. P., Blake, D. R., Benjamin, N., Stevens, C. R., Winyard, P. G., Symons, M. C. R., Harrison, R., Human xanthine oxidase converts nitrite ions into nitric oxide. Biochem. Soc. Trans. 25 (1997), p.524S... 

The reaction in water at pH 7.4 has been much studied since the discovery of the importance of nitric oxide. The products are as for the thermal and photochemical reactions, except that the final product is nitrite ion. This is to be expected since nitric oxide in aerated water at pH 7.4 also yields quantitatively nitrite ion25, by it is believed the series of equations 7-9, which involves oxidation to nitrogen dioxide, further reaction to give dinitrogen trioxide which, in mildly alkaline solution, is hydrolysed to nitrite ion. Under anaerobic conditions it is possible to detect nitric oxide directly from the decomposition of nitrosothiols using a NO-probe electrode system26. Solutions of nitrosothiols both in... 

An improved HPLC-photohydrolysis-colorimetry method was validated for twenty-eight reference nitrosamines. These were separated by HPLC and photolytically cleaved by UV radiation. The resulting nitric oxide was oxidized and hydrolyzed to nitrite ions, which were derivatized into an azo dye with Griess reagent and measured spectrophoto-metrically. The method was applied to separate and detect hitherto unknown nonvolatile nitrosamines in biological fluids and food extracts591. 

Soil Under aerobic conditions, acrylamide degraded to ammonium ions which oxidized to nitrite ions and nitrate ions. The ammonium ions produced in soil may volatilize as ammonia or accumulate as nitrite ions in sandy or calcareous soils (Abdelmagid and Tabatabai, 1982). 

The oxidizing agents are nitrate and nitrite ions, formed by the action of sulfuric acid on explosives. This reaction, a classical test for nitrate ions [4], is not specific it involves only oxidation/reduction and no atoms from the analyte are incorporated... 

Aromatic cation-radicals can also react with NOj", giving nitro compounds. Such reactions proceed either with a preliminary prepared cation-radical or starting from nncharged componnd if iodine and silver nitrite are added. As for mechanisms, two of them seem feasible—first, single electron transfer from the nitrite ion to a cation-radical and second, nitration of ArH with the NOj radical. This radical is quantitatively formed when iodine oxidizes silver nitrite in carbon tetrachloride (Neelmeyer 1904). 

An attempt to combine electrochemical and micellar-catalytic methods is interesting from the point of view of the mechanism of anode nitration of 1,4-dimethoxybenzene with sodinm nitrite (Laurent et al. 1984). The reaction was performed in a mixture of water in the presence of 2% surface-active compounds of cationic, anionic, or neutral nature. It was established that 1,4-dimethoxy-2-nitrobenzene (the product) was formed only in the region of potentials corresponding to simultaneous electrooxidation of the substrate to the cation-radical and the nitrite ion to the nitrogen dioxide radical (1.5 V versus saturated calomel electrode). At potentials of oxidation of the sole nitrite ion (0.8 V), no nitration was observed. Consequently, radical substitution in the neutral substrate does not take place. Two feasible mechanisms remain for addition to the cation-radical form, as follows ... 

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