Benzene trinitration

Up to three of the hydrogens on a benzene ring can be replaced with a nitro (-NO2) group by reaction of nitric acid in sulfuric acid. When two hydrogens are replaced by nitro in this manner (dinitration), one isomer, the meta- or 1,3-, predominates. When three hydrogens are replaced (trinitration), the predominant isomer is the 1,3,5-isomer mera-dinitrobenzene is made by this method as a starting material for mera-phenylenediamine, one of the components in the manufacture of a heat-resistant nylon sold in the U.S. as Nomex by DuPont. 

The powerful nature of nitronium salts as nitrating agents is demonstrated in their ability to affect even trinitration of benzene to trinitrobenzene [Eq. (5.174)].475 Nitronium salts enable nitration of every conceivable aromatic substrate. 

It is produced by nitration of toluene with mixed nitric and sulfuric acid in several steps. The trinitration step needs high concentrated mixed acids with free S03. There are batchwise and continous nitration methods. TNT for military use must be free from any isomer other than the 2,4,6 (the specifications). This can be done by recrystallization in organic solvents (alcohol benzene) or in 62% nitric acid. The non-symmetrical isomers can be destroyed by washing with an aqueous sodium sulfite solution this processing, however, brings about large quantities of red colored waste waters. 

In toluene, as well as with many other monosubstituted benzenes, the substitution group (methyl, in the case of toluene) acts as an electron donor. This counters the electron-withdrawing effect of the previously substituted nitro groups and allows higher local nitronium ion activity, thus allowing a much easier trinitration step. This is the key, then, to inexpensive synthesis of trinitro-aromatic explosives. Figure 3.5 is the TNT molecule, the first, and most important (as far as quantity of production goes) of the monosubstituted TNBs. 

Called in Beil N-[3 Nitro-phenyl]-2,4,6-trinitrophenylendiamin-(l,3)l, H, N(0,N),--C H-NH-CjH NO,. Crysts(from et acet), mp 272°(decomp). Can be prepd either by heating 2,3,4,6-tetranitroaniline with 3 nitrobenzene in benzene or by fusing N-nitro-N-methy 1-2,4,6-trinitr 0-1,3 phe nylenedi amine with 3-nitroaniline at 110—120°. Its ezpl props were not reported... 

It is significant to note, however, that with highly deactivated substrates, such as for example m-dinitrobenzene, nitration with nitronium salts is not talking place with any appreciable rate in aprotic solvent media (6 ). On the other hand, when using protic solvents, such as fluorosulfuric acid, the nitronium ion in the strongly acidic media can with ease trinitrate benzene (12,6 ). Similar observations were made in nitration of alkanes (22). 

The reactivity of nitronium salts is further enhanced in strong acid such as fluorosulfuric acid. Such solutions can be used to even trinitrate benzene to yield 1,3,5-trinitrobenzene, a reaction which was reported previously only in low yield [64-66]. 1,3,5-Trinitrobenzene is usually obtained only indirectly [67], but can be prepared in good yield by nitration of ftiete-dinitrobenzene with nitronium tetrafluoroborate in fluorosulfuric acid [68). Optimum reaction conditions require a reaction time of - 3 hr at 150 C, to yield 100% pure 1,3,5-trinitrobenzene in 50% yield [41,69]. The data in Table XX show that higher yields can be obtained at shorter reaction times, with mixtures of di- and trinitro products necessitating purification by HPLC. Longer reaction times give pure 1,3,5-trinitrobenzene but also result in oxidative losses and hence tower yield. 

The solubility of nitro isobutyl glycerine trinitrate in water is less than that of nitroglycerine. Its solubility at 20 °C is 0.081 % and it is mutually soluble to diethyl ether, acetone, benzene, acetic ether, tetrachlormethane, dichlormethane, nitrobenzene, and nitrotoluene. Nitro isobutyl glycerine trinitrate can dissolve nitro aromatics. The property can be used to produce double-base propellants or multibase propellants. It is, to some extent, soluble to low nitrogenous cellulose nitrate (nitrogen content 11.8-12.2 %) for the production of double-base propellants. 

See 1,3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene Phenol trinitrate Phenol, 2,4,6-trinitro-. See Picric acid... 

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