Nitration Nitro compounds

NH3) are of great commercial importance practically all modem explosives contain high proportions of ammonium nitrate or organic nitro-compounds. Nitrates are also employed as fertilizers. 

The synthesis of an aromatic amine generally starts from the corresponding nitro compound. Nitration and subsequent reduction are key reactions in the synthesis of intermediates for azo pigments. 

Yinon, J. Mass Spectrometry of Explosives Nitro Compounds, Nitrate Esters, and Nitramines. Mass Spectrom. Rev. 

Stokinger HE Aliphatic nitro compounds, nitrates, nitrites. In Clayton GD, Clayton EE (eds) Patty s Industrial Hygiene and Toxicology, 3rd ed, rev, Vol 2C, Toxicology, pp 4162-4164. New York, Wiley-Interscience, 1982... 

Nitro compounds, nitrates, and nitramines contain an N02 group. Each of these classes shows absorption caused by asymmetrical and symmetrical stretching of the N02 group. Asymmetrical absorption results in a... 

Nitro compounds, nitrates, and nitramines contain an N02 group. Each of these classes shows absorption caused by asymmetrical and symmetrical stretching of the N02 group. Asymmetrical absorption results in a strong band in the 1661-1499 cm 1 region symmetrical absorption occurs in the region between 1389-1259 cm. The exact position of the bands is dependent on substitution and unsaturation in the vicinity of the N02 group. 

A considerable number of X-ray examinations of nitro compounds have been done over the last two decades. They will be given in the description of particular compounds. However, the following are reviews which should be mentioned X-ray analysis of aliphatic nitro compounds, nitrate esters and nitramines were described by Novikov and co-workers [7], nitramines by G. F. Wright [115], polynitroaromatic addition compounds by Hall and Poranski [116]. The X-ray... 

Stokinger HE. 1982. Aliphatic nitro compounds, nitrates, nitrites. In Clayton GD, Clayton FE, eds. 

Yinon J., Mass Spectrometry of explosives Nitro compounds, nitrate esters, and nit-ramines, Mass. Spectrom. Rev., 1, 257-307, 1982. 

Cautiously add 250 g. (136 ml.) of concentrated sulphuric acid in a thin stream and with stirring to 400 ml. of water contained in a 1 litre bolt-head or three-necked flask, and then dissolve 150 g. of sodium nitrate in the diluted acid. Cool in a bath of ice or iced water. Melt 94 g. of phenol with 20 ml. of water, and add this from a separatory funnel to the stirred mixture in the flask at such a rate that the temperature does not rise above 20°. Continue the stirring for a further 2 hours after all the phenol has been added. Pour oflF the mother liquid from the resinous mixture of nitro compounds. Melt the residue with 500 ml. of water, shake and allow the contents of the flask to settle. Pour oflF the wash liquor and repeat the washing at least two or three times to ensure the complete removal of any residual acid. Steam distil the mixture (Fig. II, 40, 1 or Fig. II, 41, 1) until no more o-nitrophenol passes over if the latter tends to solidify in the condenser, turn oflF the cooling water temporarily. Collect the distillate in cold water, filter at the pump, and drain thoroughly. Dry upon filter paper in the air. The yield of o-nitrophenol, m.p. 46° (1), is 50 g. 

Nitro compounds and their reduction products. Tertiary nitro compounds (these are generally aromatic) are reduced by zinc and ammonium chloride solution to the corresponding hydroxylamines, which may be detected by their reducing action upon an ammoniacal solution of silver nitrate or Tollen s reagent ... 

Nitration is important for two reasons firstly, because it is the most general process for the preparation of aromatic nitro compounds secondly, because of the part which it has played in the development of theoretical organic chemistry. It is of interest because of its own characteristics as an electrophilic substitution. 

Olah s original preparative nitrations were carried out with mixtures of the aromatic compound and nitronium salt alone or in ether, and later with sulpholan as the solvent. High yields of nitro-compounds were obtained from a wide range of aromatic compounds, and the anhydrous conditions have obvious advantages when functional groups such as cyano, alkoxycarbonyl, or halogenocarbonyl are present. The presence of basic fimctions raises difficulties with pyridine no C-nitration occurs, i-nitropyridinium being formed. ... 

In nitration with nitronium salts in sulpholan, nitrobenzene was substituted in the following proportions 8% ortho, 90% meta and 2% paraf under the same conditions benzylidyne trifluoride yielded 8%, 88% and 4% of 0-, m- and p-nitro compound respectively Both of these aromatic compounds were stated to be io -10 times less reactive than benzene. "... 

Nitrations in acetic anhydride, or in solutions containing benzoyl nitrate ( 5.2) or dinitrogen pentoxide ( 4.2.3) have long been associated with the formation from some aromatics of higher proportions of o-nitro-compounds than are formed under other conditions. 

That some modification to the position so far described might be necessary was indicated by some experiments of Nesmeyanov and his co-workers. Amongst other compounds they nitrated phenyl trimethyl ammonium and triphenyloxonium tetrafluoroborates with mixed acid the former gave 96 % of m- and 4 % of -nitro compound (88 % total yield), whilst the latter gave 80% of the tri-(p-nitrophenyl)oxonium salt. Ridd and his co-workers have made a quantitative study of the phenyl trimethyl ammonium ion. Their results, and those of other recent workers on the nitration of several cations, are collected in table 9.3. 

Comparison of data for the nitration of alkyl- and halogenobenzenes with those for the related p-nitro-compounds supports the view that the rate of nitration of highly electron-deficient systems is determined by polarizability factors which enhance the reactivity of the substituted by comparison with that of the unsubstituted system. 

About 5 % of an unidentified product was formed as well as the proportions of nitro-compounds given for nitration in 84 9 % sulphuric acid. 

Little is known quantitatively about substituent effects in the nitration of derivatives of azanaphthalenes. In preparative experiments 4-hydroxy-quinoline, -cinnoline, and -quinazoline give the 6- and 8-nitro compounds, but with nitric acid alone 4-hydroxyquinoline and 2,4-di-hydroxyquinoline react at With nitric acid, 4-hydroxycinnoline... 

The case of i-methyl-4-quinolone is puzzling. The large proportion of the 3-nitro isomer formed in the nitration (table 10.3 cf. 4-hydroxyquinoline) might be a result of nitration via the free base but this is not substantiated by the acidity dependence of the rate of nitration or by the Arrhenius parameters. From r-methyl-4-quinolone the total yield of nitro-compounds was not high (table ro.3). 

Comparison of the behaviour of cinnoline 2-oxide (vi, i = O) with that of 2-methoxycinnolinium (vi, R = OMe) suggests that at high acidities the former is nitrated as its conjugate acid (vi, R = OH), but that as the acidity is lowered the free base becomes active. At high acidities 5- and 8-nitration are dominant, but as the acidity is lowered 6-nitration becomes increasingly important. The 5- and 8-nitro compounds are probably formed mainly or wholly by nitration of the conjugate acid, and the 6-nitro compound wholly or mainly from the free base. ... 

Nitroethane and 1-(3,4 methylenedioxy) 2- nitropropane This method of producing the above mentioned nitro compounds is by far the best Ritter has come across yet The problem with standard nitroethane synthesis is that the -NO2 source most commonly used is silver nitrite (a la Merck Index citing). Needless to say, this is going to be an expensive compound to make as it is not available commercially but must be synthesized from costly silver nitrate. The other methods mentioned in Vogels 5th masterpiece... 

The 2-benzamido 4-aryl(alkyl)selenazoles (96) form the corresponding 5-nitro derivatives under mild conditions using the nitrate-sulfuric acid method (Scheme 31). The nitro compounds are well-defined, ciy s-talline compounds. They may be most favorably obtained by dissolving the 2-benzamidoselenazoles in acetone and adding concentrated nitric... 

The overall reactivity of the 4- and 5-positions compared to benzene has been determined by competitive methods, and the results agreed with kinetic constants established by nitration of the same thiazoles in sulfuric acid at very low concentrations (242). In fact, nitration of alkylthiazoles in a mixture of nitric and sulfuric acid at 100°C for 4 hr gives nitro compounds in preparative yield, though some alkylthiazoles are oxidized. Results of competitive nitrations are summarized in Table III-43 (241, 243). For 2-alkylthiazoles, reactivities were too low to be measured accurately. 

The bath components for a nitrite—nitrate accelerated bath basic to this conversion coating process are (/) 2inc metal or 2inc oxide dissolved in acid (2) phosphate ions added as phosphoric acid (J) addition of an oxidant such as sodium nitrite and (4) addition of nitric acid. Other oxidants such as peroxide, chlorate, chlorate in combination with nitrate, or an organic nitro compound may also be used. 

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