Nitrating agent sulfuric-nitric acid mixture

The nitronium ion, N02 , is the active nitrating agent in nitric acid-sulfuric acid mixtures. The nitration of methylbenzene (toluene) is a typical example of a nitration that proceeds well using nitric acid in a 1 2 mixture with sulfuric acid. The nitration product is a mixture of 2-, 3-, and 4-nitromethylbenzenes ... 

Abstract Synthesis methods of various C- and /V-nitroderivativcs of five-membered azoles - pyrazoles, imidazoles, 1,2,3-triazoles, 1,2,4-triazoles, oxazoles, oxadiazoles, isoxazoles, thiazoles, thiadiazoles, isothiazoles, selenazoles and tetrazoles - are summarized and critically discussed. The special attention focuses on the nitration reaction of azoles with nitric acid or sulfuric-nitric acid mixture, one of the main synthetic routes to nitroazoles. The nitration reactions with such nitrating agents as acetylnitrate, nitric acid/trifluoroacetic anhydride, nitrogen dioxide, nitrogen tetrox-ide, nitronium tetrafluoroborate, V-nitropicolinium tetrafluoroborate are reported. General information on the theory of electrophilic nitration of aromatic compounds is included in the chapter covering synthetic methods. The kinetics and mechanisms of nitration of five-membered azoles are considered. The nitroazole preparation from different cyclic systems or from aminoazoles or based on heterocyclization is the subject of wide speculation. The particular section is devoted to the chemistry of extraordinary class of nitroazoles - polynitroazoles. Vicarious nucleophilic substitution (VNS) reaction in nitroazoles is reviewed in detail. 

Aminothiazole is converted by the action of ethyl nitrate into the 5-nitro derivative [352], As already mentioned 2-phenyloxazole and 2-phenylthiazole are nitrated into benzene ring by the sulfuric-nitric acid mixture. At the same time their nitration under conditions excluding protonation of the azole ring (with the use of acetylnitrate or /V-nitropicolinium tetrafluoroborate as nitrating agent) leads to the 5-nitro derivatives [353] (Scheme 40). 

Currently the most economical route to making dinitramides involves a mixture of nitric and sulfuric acids as the nitrating agent. The mixed acid is drastically less expensive than the nitration agents mentioned above. The substrate is potassium sulfaminate, which, due to its basicity, is suitable for nitration in a strongly acidic solution. Since the dinitramide anion is thermally unstable in acidic environment at room temperature, the nitration is carried out at -30°C to -40°C. 

NITRATING ACID [legal label name for various concentrations of sulfuric and nitric acid mixtures (mixed acid often 61% sulfuric/36% nitric)]. A strong oxidizer. Violent reaction with reducing agents, bases, 1,2-dimethyl-2-trimethylsilylhydrazine, phthalic anhydride, lithium-2,2-dimethyltrimethylsilyl hydrazide, nitronaphthalene, organic solvents, and other organic materials. Violent reaction when water is added to acid to dilute, always add acid to water. See Nitric Acid and Sulfuric Acid. 

Nitration of 4-(2-thienyl)- (301) and 4-(3-thienyl)-pyrazoles (302) mainly occurs on the thiophene ring, but when acetyl nitrate is used as the nitration agent small quantities of products nitrated on the pyrazole ring are isolated (position of the nitro group uncertain) (80CS( 15)102). Pyrazol-l -ylpyridines (303) undergo electrophilic reactions (bromination, chlorination and nitration) preferentially in the pyrazole ring. Thus, the nitration of (303 R = R = = H) either with a mixture of nitric acid and sulfuric acid at 10-15 °C or with... 

One of the most extensively studied examples of electrophilic substitution is the nitration of benzene. A mixture of nitric acid and concentrated sulfuric acid converts benzene slowly into nitrobenzene. The actual nitrating agent is the electrophile NQ2+ (the nitronium ion, ONO ), a linear triatomic ion ... 

As mentioned in a patent [17], the nitration of 3-trifluoromethylindazole results in a mixture of 5-nitro- and 7-nitro-isomers. If the mixture of nitric and sulfuric acids is used as a nitrating agent, the formation of 3-methyl-7-nitroindazole as a by-product is observed [11], Nitration of 3-chloro-2-phenylindazole with a mixture... 

The nitration of organic compounds still occurs almost exclusively using mixed acid or 65% to 100% HN03. Mixed acid is a mixture of concentrated nitric acid and concentrated sulfuric acid, which acts as a very strong nitrating agent due to the presence of the N02 ion. 

Aromatic compounds are usually nitrated in liquid phase by treatment with a mixture of concentrated nitric acid and concentrated sulfuric acid. Sulfuric acid serves as a dehydrating agent which prevents dilution of the nitric acid by the liberated water. Acetic anhydride in acetic acid and boron trifluoride also serve this purpose. 

The nitrating agents for the manufacture of explosives via C-nitration, 0-nitration, or N-nitration are mixtures of nitric and sulfuric acids, except for RDX and HMX where a mixture of nitric acid and ammonium nitrate is used [4]. 

Most aromatic compounds, whether of high or low reactivity, can be nitrated, because a wide variety of nitrating agents is available. For benzene, the simple alkylbenzenes, and less reactive compounds, the most common reagent is a mixture of concentrated nitric and sulfuric acids,but for active substrates, the reaction can be carried out with nitric acid alone, or in water, acetic acid, acetic anhydride, or chloroform.Nitric acid in acetic anhydride/trifluoroacetic anhydride on zeolite H-(3 was used to convert toluene to 2,4-dinitrotoluene, and AcONOi on clay converted ethylbenzene to ortho-para nitro ethylbenzene. " In fact, these milder conditions are necessary for active compounds, such as amines, phenols, and pyrroles, since reaction with mixed nitric and sulfuric acids would oxidize these substrates. With active substrates, such as amines and phenols, nitration can be accomplished by nitrosation under oxidizing conditions with a mixture of dilute nitrous and nitric acids.A mixture of N02/02/Fe(acac)3 can be used for active compounds, as can NaN02 with trichloroisocyanuric acid on wet silica gel, or N2O4 and silica acetate. Trimethoxybenzenes were nitrated easily with ceric ammonium nitrate on silica gel, and mesitylene was nitrated in an... 

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