2.4- Dimethylaniline, nitration

All is stirred for one hour longer and then the product is cooled (still stirring). After being allowed to crystallize, it is centrifuged. The dinitromethylaniline so obtained is nitrated in a similar manner to dimethylaniline. Nitration proceeds without such an abundant evolution of gaseous products, it is less violent and may be conducted at a lower temperature. 

On acetylation it gives acetanilide. Nitrated with some decomposition to a mixture of 2-and 4-nitroanilines. It is basic and gives water-soluble salts with mineral acids. Heating aniline sulphate at 190 C gives sulphanilic add. When heated with alkyl chlorides or aliphatic alcohols mono- and di-alkyl derivatives are obtained, e.g. dimethylaniline. Treatment with trichloroethylene gives phenylglycine. With glycerol and sulphuric acid (Skraup s reaction) quinoline is obtained, while quinaldine can be prepared by the reaction between aniline, paraldehyde and hydrochloric acid. 

It is prepd by the action of methylamine on 4-chloro-l-nitrobenzene (Ref 5) by the action of methyl iodide (Ref 6), or methyl sulfate on 4-nit roaniline (Ref 7) or by the hydrolysis of 4-nitro-N-methylformanilide with hot coned aq HC1 (Ref 8). In a study of the effect of nitric acid concn on the prods of the nitration of N,N-dimethylaniline to form Tetryl, it was isolated in low yield by the action of nitric acid, d 1.046g/cc, plus Na nitrite on N,N-dimethylaniline (Ref 10). A eutectic mixt with N-ethyl-4-nitroaniline has been patented as a stabilizer for NC (Ref 12). Studies at NPF indicate that 4-nitro-N-methyl-aniline is superior to Centralite, 2-nitrodiphenyl-amine, or Acardite in stabilizing. NC Refs 1) Beil 12, 586, (295) 1125 ... 

Registry No 19092-03-6. It has been shown to be an intermediate in the prepn of Tetryl from N,N-dimethylaniline as it can be prepd from N,N-dimethylariiline or 2,4-dinitro-N-methylaniline by the action of 70% nitric acid in 90% yield (Refs 13 14) and can be nitrated to Tetryl with a mixt of 64% sulfuric acid, 15% nitric. acid, and-21%-w yield 91.9% (Ref 14). It can be isolated from commercial Tetryl and identified by thin layer chromatography (Ref 21) N,2,6-Trinitro-N-methylaniline (2,6-dinitrophenyl-methylnitramine), mp 110.8 874.9kcal/... 

N,2,4,5-Tetranitro-N-methylaniline (2,4,5-trinitrophenyl-N-m ethylnitramine), needles from nitric acid mp 143.5° prepd by nitration of 2,4,5-trimtro-N-methylaniline, or by the action of 90% nitric acid on 2,4,5-trinitro-N.N-dimethylaniline (Refs 1 3) 2,3,4,6-Tetranitro-N-methylaniline, mp 127° prepd by the action of sulfuric acid on N,2,4,5-tetranitro-N-methylaniline (Refs 2 3)... 

Tetryl. In the manufacture of Tetryl, it is usual not to nitrate dime thy laniline directly, but to dissolve it first in coned sulfuric acid and then to nitrate the dimethylaniline sulfate so obtained. Direct nitration of dimethylaniline proceeds so violently that it can be carried out only under specialized conditions. Many years experience of Tetryl manufacture has shown that the ratio of sulfuric acid to dimethylaniline should not be lower than 3 1, since a smaller amount of sulfuric acid may be detrimental to the nitration process. However, the ratio of sulfuric acid to dimethylaniline must not be too high, otherwise Tetryl yield is decreased. Temp must be maintained between 20-45° to avoid sulfonation of the benzene ring. Care must be exercised not to leave any unreacted dimethylaniline prior to introduction of nitric acid, because of the potential violence of the dimethyl-aniline-nitric acid reaction. Consequently, continuous methods of prepn are to be preferred as they inherently minimize accumulation of unreacted dimethylaniline... 

Analogies for such a mechanism in diazotization are found in the nitrous acid-catalyzed nitration of A,A-dimethylaniline, mesitylene, 4-nitrophenol, and some related compounds, which were investigated by 15N NMR spectroscopy in Ridd s group (Ridd and Sandall, 1981 Ridd et al., 1992 Clemens et al., 1984a, 1984b, 1985 Johnston et al., 1991 review Ridd, 1991). Ridd and coworkers were able to demonstrate clearly that not only the nitration proper, but also the preceding C-nitrosation, is accompanied by a marked 15N nuclear polarization. This was at-... 

It was discovered by Michler and Meyer in 1879 and was made by the nitration of dimethylaniline. One methyl group is oxidised and at the same time the benzene nucleus is nitrated in the 2, 4, 6-positions. The usual method of preparation from dimethylaniline is to dissolve 1 part of dimethylaniline in 14 to 15 parts of sulphuric acid to this solution about 9 parts are added of a mixed acid containing 67% of nitric acid and 16% of... 

Chemical/Physical. Products identified from the gas-phase reaction of ozone with N,N-dimethylaniline in synthetic air at 23 °C were A-methylformanilide, formaldehyde, formic acid, hydrogen peroxide, and a nitrated salt having the formula [C0H6NH(CH3)2] NO3 (Atkinson et al, 1987). Reacts with acids forming water-soluble salts. 

Nitrations of aromatic amines often involve the intermediate formation of N-nitramines, although these are rarely seen under the strongly acidic conditions of mixed acid nitration (Section 4.5). N,2,4,6-Tetranitro-N-methylaniline (tetryl) is an important secondary high explosive usually synthesized from the nitration of N,N-dimethylaniline or 2,4-dinitro-N-methylaniline. ° The synthesis of tetryl is discussed in Section 5.14. 

Tetryl (8) can be prepared from the nitration-oxidation of A, A-dimethylaniline (90) with a variety of nitrating agents and conditions, including the use of a large excess of 70 % nitric... 

Trichlorobenzene, Nitric acid. Sulfuric acid Sulfuric acid. Sodium nitrate, Meta-nitroanUine Sulfuric acid. Nitric acid, Meta-nitroanUine Isocyanogen tetrabromide. Acetone, Sodium azide Nitric acid. Sulfuric acid, N,N-Dimethylaniline DimethylanUine, Sulfuric acid. Nitric acid... 

Nitration of dimethylaniline results in the oxidation of one of the methyl groups to the carboxyl group which is not strongly linked to nitrogen and is readily split off as carbon dioxide. Thus, as the nitration of dimethylaniline proceeds, gases consisting of NO and N02 (from the reduction of nitric acid) and of C02 (from the oxidized N-methyl group) are evolved abundantly. 

Hodgson and Turner [5] examined the action of various concentrations of nitric acid alone on dimethylaniline, by nitrating 5 g test specimens of the latter on a laboratory-scale. 

They also obtained a lower-nitrated product by employing nitric acid, s.g. 1.42 at 0°C. Later authors (Clarkson, Holden and Malkin [4]) found that this pioduct was N-2,4-trinitroethylaniline. At room temperature the reaction proceeds violently and decomposition with a tendency to explosion readily occurs in the nitrator. Nitric acid of lower concentrations, s.g. 1.34 and 1.254, gives 2,4-dimethylaniline at 0°C in quantitative yield. At a higher temperature they obtained a mixture of this compound with 2,4-dinitromethylaniline. 

Recently, T. Urbanski and Semenczuk [8] made it clear that tetryl may be safely prepared by nitrating dimethylaniline with nitric acid, s.g. 1.40. Essential safety precautions for the procedure are ... 

As early as 1938, Shorygin and Topchiyev [10] nitrated dimethylaniline with a solution of nitrogen dioxide in chloroform, but they were only able to obtain 4-nitro-dimethylaniline with a small amount of 3-nitiodimethylaniline. No demethylation of the N-dimethylamino group occurred. 

Semenczuk and T. Urbanski also showed that dimethylaniline may be nitrated to tetryl by a mixture of nitric acid with acetic acid or acetic anhydride. As yet the only other results mentioned in the literature with reference to this method are those of Orton [11]. He asserted that dimethylaniline gives no N-nitro derivative when reacted with a mixture of nitric acid with acetic anhydride or acetic acid he obtained only 2,4-dinitromethylaniline. 

The spontaneous reaction which occurred after introducing dimethylaniline into the nitrating mixture caused the tempeiature to rise to about 40°C. After the reaction subsided, it was necessary to warm the reaction mixture and to keep it at 80°C until the reaction was complete. 

Later Romburgh and Schepers [16] explained that the substance (VII) is also formed from dimethylaniline if nitration is carried out in the presence of a large excess of sulphuric acid (20-fold with respect to dimethylaniline). It is evident that the presence of this substance is undesirable owing to the poor stability of the nitro group in the meta position and to the formation of metal salts of the substance (VIII) which are sensitive to impact. 

Recently, Bogdal and D. Smolenski [18] made an extensive investigation of the conditions of formation of m-nitrotetryl. Contrary to the previous work of Romburgh [15] they found that m-nitrotetryl was formed in larger quantity when dimethylaniline was nitrated. Methylaniline yielded a smaller amount of m-nitrotetryl under identical nitration conditions. 

A lower temperature of nitration favours the formation of m-nitrotetryl, e.g. when dimethylaniline is nitrated at 65 and 0°C the corresponding percentages of m-nitrotetryl are 11 and 30%, respectively. 

These substances are insoluble in benzene and hence easily removable from tetryl by crystallization in this solvent. They are fine-crystalline products of a yellowish colour. They increase with the amount of water contained in the nitrating acid. Michler and Pattison [19] proved that N-tetramethylbenzidine is formed by heating dimethylaniline with sulphuric acid. 

The same reaction undoubtedly occurs when dimethylaniline is nitrated. Mertens [6] isolated all three substances from the reaction of nitric acid with dimethylaniline and the substances (X) and (XI) by the treatment of methylaniline with nitric acid. Van Romburgh [7, 20] elucidated the structure of these compounds, in particular the position of nitro groups. 

Nitration is usually carried out in such a way that the solution of dimethylaniline in sulphuric acid is introduced into a nitrating mixture rich in nitric acid. The nitration reaction proceeds vigorously, and it is therefore most important to control the reaction temperature. Formerly it was believed that for safety s sake the lowest possible temperature of nitration should be maintained. Later it became clear that at such a temperature nitration is not brought to completion and a large quantity of incompletely nitrated products accumulates, which may lead to an... 

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