Anions nitrite

Some 2-halogeno-5-nitrothiazoles and 2-nitro-5-halogenothiazoles are known. 2-Halogeno-5-nitrothiazoles can be prepared by a Sandmeyer reaction from 2-amino-5-nitrothiazole (1, 85), while 2-nitro-5-halo-genothiazoles can be analogously prepared by decomposition of dia-zonium salts arising from 2-amino-5-halogenothiazoles in presence of nitrite anion (82, 84). 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

Sodium nitrite in dimethylformamide acts as a nucleophile and reacts with perfluoropropene to generate a perfluoroalkyl nitrite anion The intermediate carbanion undergoes intramolecular nitrosation with loss of carbonyl difluoride to give tnfluoroacetic acid upon hydrolysis [5] (equation 6)... 

Examine atomic charges and the electrostatic potential nu for nitrite anion. Which atom(s) is most electron riel Which product would be obtained if this atom behav as a nucleophile in its reation with methyl bromide. 

Various side-reactions may complicate the course of the Nef reaction. Because of the delocalized negative charge, the nitronate anion 2 can react at various positions with an electrophile addition of a proton at the a-carbon reconstitutes the starting nitro alkane. 1. The nitrite anion can act as leaving group, thus leading to elimination products. 

Cyanide and thiocyanate anions in aqueous solution can be determined as cyanogen bromide after reaction with bromine [686]. The thiocyanate anion can be quantitatively determined in the presence of cyanide by adding an excess of formaldehyde solution to the sample, which converts the cyanide ion to the unreactive cyanohydrin. The detection limits for the cyanide and thiocyanate anions were less than 0.01 ppm with an electron-capture detector. Iodine in acid solution reacts with acetone to form monoiodoacetone, which can be detected at high sensitivity with an electron-capture detector [687]. The reaction is specific for iodine, iodide being determined after oxidation with iodate. The nitrate anion can be determined in aqueous solution after conversion to nitrobenzene by reaction with benzene in the presence of sulfuric acid [688,689]. The detection limit for the nitrate anion was less than 0.1 ppm. The nitrite anion can be determined after oxidation to nitrate with potassium permanganate. Nitrite can be determined directly by alkylation with an alkaline solution of pentafluorobenzyl bromide [690]. The yield of derivative was about 80t.with a detection limit of 0.46 ng in 0.1 ml of aqueous sample. Pentafluorobenzyl p-toluenesulfonate has been used to derivatize carboxylate and phenolate anions and to simultaneously derivatize bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulfide in a two-phase system using tetrapentylammonium cWoride as a phase transfer catalyst [691]. Detection limits wer Hi the ppm range. 

The HO—LU interaction came early to the notice of theoreticians. Hiickel 74> pointed out the role of LU in the alkaline reduction of naphthalene and anthracene. Moffitt 75> characterized the formation of S03, SO2CI2, etc. by the reactions of SO2 as an electron donor with the S-atom-localiz-ing character of HO MO. Walsh 76) considered that the empirical result of producing nitro compounds in the reaction of the nitrite anion with the carbonium ion should be attributed to the HO of the NO2 anion which is localized at the nitrogen atom. 

Nucleophilic attack by a trialkyl phosphite on a significantly electron-deficient aromatic ring involving addition-elimination of a nitro group (as nitrite anion), which completes the final step of the normal Michaelis-Arbuzov reaction (Figure... 

Studies in this laboratory (69) of the water soluble ferri-heme model Fem(TPPS) in aqueous solution have shown that this species also undergoes reductive nitrosylation in solutions that are moderately acidic (pH 4-6) (Eq. (32)). The rate of this reaction includes a buffer dependent term indicating that the reaction of the Fem(TPPS)(NO) complex with H20 is subject to general base catalysis. The reaction depicted in Eq. (33) is not observable at pH values < 3, since the half-cell reduction potential for the nitrite anion (Eq. (1)) is pH dependent, and Eq. (33) is no longer thermodynamically favorable. 

Binkley, R. W., Inversion of Configuration in 2,6-Dideoxy Sugars - Triflate Displacement by Benzoate and Nitrite Anions. J. Org. Chem. 1991, 56, 3892-3896. 

The reaction has been suggested as involving a one-electron transfer from sodium hydrogen telluride to the nitro compound followed by the detachment of a nitrite anion from the resulting radical anion. 

The synthesis of aliphatic nitro compounds from the reaction of alkyl halides with alkali metal nitrites was discovered by Kornblum and co-workers and is known as the modified Victor Meyer reaction or the Kornblum modification. The choice of solvent in these reactions is crucial when sodium nitrite is used as the nitrite soiuce. Both alkyl halide and nitrite anion must be in solution to react, and the higher the concentration of nitrite anion, the faster the reaction. For this reason, both DMF and DMSO are widely used as solvents, with both able to dissolve appreciable amounts of sodium nitrite. Although sodium nitrite is more soluble in DMSO than DMF the former can react with some halide substrates.Urea is occasionally added to DMF solutions of sodium nitrite to increase the solubility of this salt and hence increase reaction rates. Other alkali metal nitrites can be used in these reactions, like lithium nitrite,which is more soluble in DMF than sodium nitrite but is also less widely available. 

Reaction time is extremely important in avoiding the side reaction illustrated in Eq. (1.1), where the nitroalkane product reacts with nitrite anion and any nitrite ester, formed as byproduct, to give a pseudonitrole. The reaction of sodium nitrite with alkyl halides is much faster than this competing nitrosation side reaction, even so, prompt work-up on reaction completion is essential for obtaining good yields. 

The reaction of a -halocarboxylic acids with sodium nitrite has been used to synthesize ni-tromethane, nitroethane and nitropropane, although the reaction fails for higher nitroalkanes. " A number of other reactions have been reported which use nitrite anion as a nucleophile, including (1) reaction of alkyl halides with potassium nitrite in the presence of 18-crown-6, (2) reaction of alkyl halides with nitrite anion bound to amberlite resins, (3) synthesis of 2-nitroethanol from the acid-catalyzed ring opening of ethylene oxide with sodium nitrite, and (4) reaction of primary alkyl chlorides with sodium nitrite in the presence of sodium iodide. ... 

The Ter Meer reaction provides a convenient route to terminal m-dinitroaliphatic (15) compounds via the displacement of halogen from terminal Q -halonitroalkanes (11) with nitrite anion... 

The tautomeric nitronic acids of secondary nitroalkanes or their nitronate salts react with nitrous acid or alkali metal nitrites to yield pseudonitroles.These pseudonitroles are often isolated as their colourless dimers (78b) but are deep blue in monomeric form (78a). Primary nitroalkanes also form pseudonitroles (80b) but these rapidly isomerise to the nitrolic acid (80a).Reactions are commonly conducted by slowly acidifying a mixture containing the nitronate salt and the metal nitrite, during which, the nitronic acid reacts with the nitrite anion. These reactions, first discovered by Meyer, have been used to prepare 2-nitroso-2-nitropropane (78a) and acetonitrolic acid (80a) from 2-nitropropane (76) and nitroethane (22) respectively. ... 

Oxidative nitration, a process discovered by Kaplan and Shechter, is probably the most efficient and useful method available for the synthesis of em-dinitroaliphatic compounds from the corresponding nitroalkanes. The process, which is an electron-transfer substitution at saturated carbon, involves treatment of the nitronate salts of primary or secondary nitroalkanes with silver nitrate and an inorganic nitrite in neutral or alkali media. The reaction is believed ° °° to proceed through the addition complex (82) which collapses and leads to oxidative addition of nitrite anion to the nitronate and reduction of silver from Ag+ to Ag . Reactions proceed rapidly in homogeneous solution between 0 and 30 °C. 

Oxidative nitration is a one step process from nitroalkane to gem- dinitroalkane, whereas the Ter Meer reaction requires two steps (initial halogenation followed by halide displacement with nitrite anion). 

As discussed above, the nitro groups of tetranitromethane and trinitromethyl compounds are susceptible to nucleophilic attack. Both potassium iodide and alkaline hydrogen peroxide affect the reductive denitration of trinitromethyl groups to em-nitronitronates 1,1,1-trinitroethane (33) is quantitatively reduced to potassium 1,1-dinitroethane (24) on treatment with alkaline hydrogen peroxide. Nucleophiles such as potassium fluoride in DMF can displace nitrite anion from tetranitromethane. Various nucleophiles, including azide, chloride, fluoride and ethoxide have been used to displace one of the nitro groups from fluorotrinitromethane. 

Archibald and co-workers have explored the synthesis of polynitrocyclobutanes and then-derivatives. The synthesis of these compounds via the nucleophilic substitution of cyclobutyl halides with nitrite anion was ruled out at an early stage because displacement in this system is too slow for practical use. This is a consequence of the molecular strain in the cyclobutane ring, which causes carbon atoms to deviate from sp hybridization towards sp character. 

REACTION OF DIAZONIUM SALTS WITH NITRITE ANION... 

A fractional order in the nitrite anion was found. This differs from the observed behavior in a benzene series where it is second order. The explanation, according to the Scheme 69, is based on the presence of a prototropic equilibrium between the diazonitrite form 241 and the conjugate base 242. The nitro derivatives 243 were mainly formed from the diazonitrite 241 because the equilibrium 241 242 is shifted towards the undissociated form, as shown by the calculated value of the quantity... 

Nitrite reductases (NiRs)—enzymes found in several strains of denitrifying bacteria— catalyze the one-electron reduction of nitrite anion to nitric oxide (Equation 1). - In addition to the importance of this process in the global nitrogen cycle (Figure 1), further incentive for the study of the denitrification process is provided by its environmental impact, ranging from the production of NO as a pollutant and NjO as a potent greenhouse gas, to lake eutrophication due to farm runoff that contains high concentrations of nitrates and nitrites. 

Kenawy 64) immobilized ammonium and phosphonium peripheral functionalized dendritic branches on a montmorillonite supported chloromethylstyrene/methyl methacrylate copolymer (74-75). These polymer/montmorillonite-supported dendrimers were used as phase transfer catalysts (PTC) for the nucleophilic substitution reaction between -butyl bromide and thiocyanate, cyanide, and nitrite anions in a toluene or a benzene/water system. These PT catalysts could be recycled by filtration of the functionalized montmorillonite from the reaction mixture. Generally,... 

N02-dG was achieved by the selective photodissociation of persulfate anions that generate 003 and N02 by one-electron oxidation of bicarbonate and nitrite anions in solution. " The 03 site-selectively generates G(—H) in the 11-mer that combines with N02 to yield the 8-N02-dG-adducted strand in 3% following HPLC purification. The nitrated 11-mer was stable at 4°C for 4 days, but depuri-nated at room temperature at pH 7 with a half-life of 20 h. " ... 

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