Nitroanilines Trinitroaniline

Fig. 1.11 Dissociation ranges of colour indicators for determination of the acidity function H0 in H2S04-H20 mixtures (1) p-nitroaniline, (2) o-nitroaniline, (3) p-chloro-o-nitroaniline, (4) p-nitrodiphenylamine, (5) 2,4-dichloro-6-nitroaniline, (6) p-nitroazobenzene, (7) 2,6-dinitro-4-methylaniline, (8) benzalacetophenone, (9) 6-bromo-2,4-dinitroaniline, (10) anthraquinone, (11) 2,4,6-trinitroaniline. (According to L. P. Hammett and A. J. Deyrup)...

Ridd and Yoshida explored the At-nitration of aromatic nitroanilines with nitronium hex-afluorophosphate in nitromethane with the aim of studying the Bamberger rearrangement (Chapter 4, Section 4.5). In was found that amines of low basicity essentially undergo complete A -substitution if the amine is in excess 2,4-dinitroaniline and 2,3-dinitroaniline form A, 2,4-trinitroaniline and At,2,3-trinitroaniline, respectively, as the sole products. More basic nitroanilines give mixtures of C-substituted, At-substituted and poly-substimted materials. The use of nitronium salts for At-nitration has been extensively reviewed. ... 

Trinitroaniline Nitrate, (OaN),C6Hj--NH2.HNO mw 389.12, N 24.23%, OB to CO, -30.5%. Crysts (from ale), which defl on heating. Was prepd by adding a chilled mist of p-nitroaniline with fuming nitric acid to chilled oleum and allowing to stand until crysts are formed... 

Strongly negatively substituted 4-nitroanilines, such as 2,4,6-trinitroaniline [489-98-5], 2,4-dinitro-6-cyanoaniline [22603-53-8], 2-methanesulfonyl-4-nitro-6-cyanoaniline, and 2,6-dicyano-4-nitroaniline [20033-48-1], are difficult to diazo-tize, and their diazonium salts tend to decompose extensively during the coupling process [15], This results in diminished yields and loss of clarity of the dyes. 

Trinitroaniline is prepared by reacting trinitrochlorobenzene with ammonia or by nitration of 4-nitroaniline. 

The Hammett postulate in essence is that the quantity yB yB H+/yB H+yB" is unity, independent of the medium and of the particular indicator in the series. For solvents of high dielectric constant and for the closely similar nitroaniline indicators, both theoretical expectation and experimental justification uphold this postulate. By the use of (4-120), values of pK for the various nitroaniline indicators were measured up to a pK value of —10.10 for 2,4,6-trinitroaniline. 

Trinitroaniline, orange-red crystals from alcohol, m.p. 186 1 has but little interest as an explosive for the reason that other more powerful and more valuable explosives may be prepared from the same raw materials. It may be prepared by nitrating aniline in glacial acetic acid solution or by the use of mixed nitric-sulfuric acid in which no large excess of sulfuric acid is present. The presence of nitrous acid must be avoided, as this attacks the amino group, replaces it by hydroxyl, and results in the formation of picric acid. The nitration of aniline in the presence of a large amount of concentrated sulfuric acid yields m-nitroaniline and later the nitro compounds which are derived from it. 

Nitration of p-nitroaniline (15b), or reacting picric acid with phosphorus pentachloride, yields trinitrochlorobenzene, which on amination affords 2,4,6-trinitroaniline, the explosive picramide. Phosgenation of /V-ethylaniline (26) gives a substituted urea used as a stabilizer for explosives. Diphenylamine (8) is used as a stabilizer, for nitrocellulose explosives as well as for celluloid, and also as a solid rocket propellant. Ethylaniline 26 is employed in the manufacture of centralite, a stabilizer in smokeless powder. Other uses for 15b, the largest volume nitroaniline, include in the production of dyes, antioxidants and pharmaceuticals. 

Figure 2. The ionization ratio measured for a series of indicators plotted against the weight percent of sulfuric acid in the H2O—H2SO4 system. (Reprinted from Ref 12 with permission of the American Chemical Society.) 1 p-Nitroaniline, 2 o-nitroaniline, 3 4-chloro-2-nitroaniline, 4 p-nitrodiphenylamine, 5 2,4-dichloro-6-nitroaniline, 6 p-nitroazobenzene, 7 2,6-dinitro-4-metiiylaniline, 8 2,4-dinitroaniline, 9 A, A -dimethyl-2,4,6-trinitroaniline, 10 benzalacetophenone, 11 8-benzoylnaphthalene, 12 p-benzoyldiphenyl, 13 6-bromo-2,4-dinitroaniline, 14 anthraquinone, 15 2,4,6-trinitroaniline. (Reprinted fi-om Ref 12 with permission fi-om the American Chemical Society.)...

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