Nitration Nitrones

It is the purpose of the series to review the field of organic nitro chemistry in its broadest sense by including structurally related classes of compounds such as nitroamines, nitrates, nitrones, and nitrile oxides. It is intended that the contributors, who are active investigators in various facets of the field, will provide a concise presentation of recent advances that have generated a renaissance in nitro chemistry research. 

Nitrogen-oxygen systems acyclic nitroamino nitrates nitrones... 

N03- Nitron nitrate Nitron nitrate CIO4, 1, SCN -, CrOl, CIO3-. NO2. Br -, C2O -... 

Transformations of nitro compounds, nitrones, nitrates, hydroxylamines, and amino-A-oxides into heterocycles 98SL939. 

Determination of nitrate as nitron nitrate Discussion. The mono-acid base nitron, C20H16N4, forms a fairly insoluble crystalline nitrate, C20H 16N4,HN03 (solubility is 0.099 g L 1 at about 20 °C), which can be used for the quantitative determination of nitrates [see Section 11.11(E)]. The sulphate and acetate are soluble so that precipitation may be made in sulphuric or acetic (ethanoic) acid solution. Perchlorates (0.08 g), iodides (0.17 g), thiocyanates (0.4 g), chromates (0.6 g), chlorates (1.2g), nitrites (1.9 g), bromides (6.1 g), hexacyanoferrate(II), hexacyanoferrate(III), oxalates, and considerable quantities of chlorides interfere, and should be absent. The figures in parentheses are the approximate solubilities of the nitron salts in g L-1 at about 20 °C. 

Nickel, sepn. of plus cobalt, (cm) 583 Nickel ware 96 Nioxime 439, 474 NITA (nitriloacetic acid) 57 Nitrates, D. of as nitron nitrate, (g) 484 by ammonium iron(II) sulphate, (am)... 

Analytical. Mannitol Hexanitrate can be hydrolyzed in basic soln and the soln acidified in the presence of NITRON to quanty ppt NITRON nitrate (Ref 16). A procedure is described for. the quant detn of nitrate esters, including Mannitol Hexanitrate, in the presence of aromatic nitro compds in Ref 17. It gives a yellow color when treated in et ale or acet with 5% aq K hydroxide, then 5% aq ammonia (Ref 24), It can be quanty detd by reduction with Devarda s alloy (Encycl 5, D-l 110) or A1 wire in aq et ale and titration of the evolved... 

Nitron fonns v si sol compds with metallic nitrates, perchlorates, picrates, trinitrocresylates, as well as with organic nitrates such as NG,... 

NC Nitromannitol etc and can serve as a gravimetric reagent. The Nitron method for the detn of N is based on the fact that it ppts inorganic nitrates from w soln, and forms an insol addition product, C20H16N4.HNO3, mw 375.3... 

Nitronate(47a) is not the only oxazete derivative. For example, sterically hindered nitroalkenes (42b-d) can be prepared by nitration and halogenation of readily available allenes (48). Compounds (42b-d) are rather smoothly isomerized into the corresponding four-membered cyclic nitronates (47b-d) by the first-order reaction equation (168). Storage of nitronate (47c) is accompanied by its slow transformation into acid chloride (47e) from which amide (47f) can be easily synthesized. 

However, this oxime can be generated via another pathway involving 1,3-addition of acetyl chloride to nitronate (120) followed by elimination of acetyl nitrate. 

Nitrones, reaction with olefins, 46, 130 Nitronium tetrafluoroborate, from nitric add, boron trifluoride, and hydrogen fluoride, 47, 56 in nitration of aromatic rings, 47, 60... 

A few nucleophiles either did not give any spin adduct with PBN or directly gave the benzoyl nitrone [9], Bromide ion did not give any spin adduct, explicable by the very short lifetime of Br-PBN (Rehorek and Janzen, 1984) and trifluoroacetate, nitrate, phenylsulfinate and chloride ion produced [9]. This can either be explained by the rapid further oxidation of the spin adduct formed [similar to reaction (29) see Table 4] or a rapid solvolysis reaction of the latter (Scheme 2), forming [9] by reaction of the intermediate carbocation... 

Nitrogen - the atomic number is 7 and the chemical symbol is N. The name derives from the Latin nitrum and Greek nitron for native soda and genes for forming because of nitrogen s presence in potassium nitrate (KNO3), so called salpeter or nitre or native soda. It was discovered by the Scottish physician and chemist Daniel Rutherford in 1772. 

Technetium can also be precipitated and weighed as nitron pertechnetate CjqHj N TcO which is precipitated at 80 °C from a weak sulfuric acid or acetic acid solution with an excess of a solution of 5% nitron in 3% acetic acid. The precipitate is washed with cold water, dried at 100 °C and weighed. Nitrate, perchlorate, permanganate, periodate, chloride, bromide, and iodide ions disturb the determination. 

Decarboxylation of 1,3-dimethylorotic acid in the presence of benzyl bromide yields 6-benzyl-1,3-dimethyluracil and presumably involves a C(6) centered nucleophilic intermediate which could nonetheless have either a carbene or ylide structure. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been used to explore the gas-phase reactions of methyl nitrate with anions from active methylene compounds anions of aliphatic ketones and nitriles react by the 5n2 mechanism and Fco reactions yielding N02 ions are also observed nitronate ions are formed on reaction with the carbanions derived from toluenes and methylpyridines. 

Nitronate salts can react with alkyl halides to yield polynitroaliphatic compounds with varying degrees of success. The main by-products of these reactions arise for competitive 0-alkylation. Alkyl nitrates are formed as by-products when the nitroform anion is used in these reactions. ... 

Nitronate salts and the tautomeric act-form of nitroalkanes, known as nitronic acids, are converted to gem-dinitro compounds on treatment with dinitrogen tetroxide. Novikov and co-workers synthesized phenyldinitromethane by treating phenylnitromethane with dinitrogen tetroxide in ether and later reported the synthesis of some substituted phenyltrinitromethanes from the direct nitration of the nitronate salts of phenylnitromethanes. 

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. 

A major drawback of the Kaplan-Shechter reaction is the use of expensive silver nitrate as one of the reagents, which prevents scale up to an industrial capacity. Urbanski and co-workers modified the process by showing that the silver nitrate component can be replaced with an inorganic one-electron transfer agent like ferricyanide anion. In a standard procedure the nitroalkane or the corresponding nitronate salt is treated in alkaline media with potassium... 

Feuer and co-workers extended their studies to the alkaline nitration of a,Nitration with potassium ferf-butoxide and amyl nitrate in THF at —30 °C yields the corresponding dipotassium salt of the a,nitronate salts from these reactions are isolated via methanol-induced precipitation from the aqueous reaction liquors, a process which also separates the product from impurities. These salts undergo hydrolysis on treatment with aqueous potassium hydroxide, and subsequent acidification yields the corresponding Q, y-dinitroalkane. This route has been used to synthesize 1,4-dinitrobutane (27) from apidonitrile (95) in 30 % overall yield. 

Mannich bases derived from polynitroalkanes are usually unstable because of the facile reverse reaction leading to stabilized nitronate anions. The nitration of Mannich bases to nitramines enhances their stability by reducing the electron density on the amine nitrogen through delocalization with the nitro group. The nitration of Mannich bases has been exploited for the synthesis of numerous explosives, some containing both C-NO2 and N-NO2 functionality. Three such compounds, (163), (164) and (165), are illustrated below and others are discussed in Section 6.10. 

Paquette and co-workers synthesized the 5,11-dinitro isomer of 1,3-bishomopentaprismane (95) by treating the dioxime (94) with a buffered solution of m-CPBA in refluxing acetonitrile. A significant amount of lactone by-product (96) is formed during this step and may account for the low isolated yield of (95). Oxidative nitration of (95) with sodium nitrite and potassium ferricyanide in alkaline solution yields a mixture of isomeric trinitro derivatives, (97) and (98), in addition to the expected 5,5,11,11-tetranitro derivative (99), albeit in low yield. Incomplete reactant to product conversion in this reaction may result from the low solubility of either (97) or (98) in the reaction medium, and hence, incomplete formation of the intermediate nitronate anions. 

Triazoles have been used extensively in analytical chemistry. Nitron (182) has been used for the determination of boron, rhenium, and tungsten. Nitron has been bonded to a polymer and used for the removal of nitrate from water <79Mi 402-oi >. Other triazoles have been used for the spectrophoto-metric assay of cobalt, rhodium, and platinum <68Mi 402-01,72ZAK2209). Hydroxyphenylazotriazoles form brilliant lakes with a number of metal ions <73AJC1585>. 5-" C-3-Diazotriazole couples only to tryptophane below pH 6.8 and can used for the specific determination of tryptophane in proteins <84M1 402-02). 

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