1.1.1- Trinitro compounds

Electrophilic substitution reactions of diarylamines are easily accompHshed since the amino group activates the aromatic ring. Thus, DPA reacts with bromine or chlorine to form the 2,2H,4 tetrahalo derivative nitration usually produces the trinitro compound. 

The crude product contains isomers other than that required and also nitrated phenolic compounds resulting from side reactions. The usual method of purification is to treat the crude product with sodium sulphite, which converts asymmetric trinitro compounds to sulphonic acid derivatives, and to wash out the resulting soluble products with alkaline water. The purity of the product is determined by the melting point, the minimum value for Grade I TNT commonly being 80-2°C. Unless adequate purity is achieved, slow exudation of impurities can occur during storage and the TNT then becomes insensitive. 

Explosive decomposition occurred during attempted vacuum distillation, attributed either to the presence of some trinitro compound in the unpurified dinitrophenylacetic acid used, or to the known instability of o-nitro acid chlorides. A previous publication (ibid., 407) erroneously described the decomposition of 2,4-dinitrobenzoyl chloride. 

An air dried sample of the lead salt of trinitrosophoroglucinol exploded when disturbed, possibly owing to aerobic oxidation to the trinitro compound. 

Ito, S. and Kamovsky, M. J. (1968) Formaldehyde-glutaraldehyde fixatives containing trinitro compounds. J. Cell Biol. 39,168a. 

Ammonium nitrate explosives usually contain a certain amount of nitro compounds from mononitro (e.g. nitronaphthalene) to trinitro compounds (e.g. trinitrotoluene). 

Crude TNT contains isomers and nitrated phenolic compounds resulting from side reactions. The usual method of purification is to treat crude TNT with 4% sodium sulfite solution at pH 8-9, which converts the unsymmetrical trinitro compounds to sulfonic acid derivatives. These by-products are then removed by washing with an alkaline solution. Pure TNT is then washed with hot water, flaked and packed. It is important to remove the waste acid and unsymmetrical trinitrotoluenes together with any by-products of nitration as they will degrade the TNT, reduce its shelf life, increase its sensitivity and reduce its compatibility with metals and other materials. Trace amounts of unsymmetrical trinitrotoluenes and by-products will also lower the melting point of TNT. TNT can be further recrystallized from organic solvents or 62% nitric acid. 

Trimonite Trinitro- Compounds See under corresponding parent Red compds Orn No ppt r ... 

The. nitration of m-dinitrobenzene is too expensive of acid and of heat for practical application, and the yields are poor. Toluene and chlorobenzene are nitrated more easily and more economically, and their trinitro compounds are feasible materials for the preparation of TNB. Oxidation with nitrosulfuric acid has obvious disadvantages. The quickest, most convenient, and cheapest method is probably that in which TNT is oxidized by means of chromic acid in sulfuric acid solution. 

Resorcinol nitrates readily to the trinitro compound, yellow prisms from water or alcohol, m.p. 175.5°. Styphnic acid is more expensive and less powerful than picric acid. Liouville67 found that styphnic acid exploded in a manometric bomb, at a density of loading of 0.2, gave a pressure of 2260 kilos per sq. cm., whereas picric acid under the same conditions gave a pressure of 2350 kilos per sq. cm. It did not agglomerate to satisfactory pellets under a pressure of 3600 kilos per sq. cm. It is a fairly strong dibasic acid, and its salts are notably more violent explosives than the picrates. Lead styphnate has been used to facilitate the ignition of lead azide in detonators. 

A solution of sodium nitrite in concentrated sulphuric acid, which provides a nitrosonium hydrogen sulphate reagent, is a very effective diazotising medium which is particularly valuable for even more weakly basic amines, such as 2,4-dinitroaniline or the corresponding trinitro compound, picramide. 

The greater stability of the 1 1 adducts in aprotic solvents is, then, attributed mainly to the enhanced reactivity of the attacking nucleophiles in these solvents. This factor should also favour the production of di-adducts in aprotic solvents and NMR measurements do indicate that these are formed from trinitro-substituted compounds and methoxide ions in media rich in dimethyl sulphoxide. However, there is some evidence that the di-adducts are not particularly well solvated by dimethyl sulphoxide and are in fact better solvated by water. Thus it has been found that 1 2 adducts are very readily formed in water. For example 1,3,5-trinitrobenzene gives both 1 1 and 1 2 adducts in fairly dilute solutions of hydroxide ions in water, while dimethyl-picramide and the picrate ion give evidence only for the production of 1 2 adducts. Similarly a variety of trinitro-compounds are readily converted into di-adducts in aqueous sodium sulphite solution, although... 

Brand Mid his co-workers [17] CMiied out extensive studies on the absorption spectra of Momatic compounds in sulphuric acid solutions, i.e. in a strongly proto-nizing solvent. They found that under the influence of the sulphuric acid the maximum of the nitro group shifted. These shifts were most pronounced in the case of mononitro compounds, Mid the least in the case of trinitro compounds. They were smaller when sulphuric acid was used as a solvent, Mid larger when oleum was used. The absorption curves for 2,4-dinitrotoluene Me shown in Fig. 

Dinitrotoluene does not give this reaction. Trinitro compounds (such as sym-trinitrobenzene and a- trinitrotoluene) also give the colour reaction but this is less typical, as the trinitro compounds give a similar colour with alcoholic NaOH alone without primary nitroparaffins. 

The formation of coloured compounds was used by Brockmann and Meyer [71] for the quantitative determination of polynitro compounds. The di- or trinitro compound is dissolved in ethylenediamine and titrated potentiometricallv... 

As shown by T. Urbanski [143] between 1933 and 1937, there is a group of molecular addition compounds whose existence cannot be explained by all the points mentioned above. They are addition compounds of certain nitro compounds with esters of nitric acid. Thus many aromatic mononitro compounds form addition compounds with mannitol hexanitrate, and some aromatic trinitro compounds do so with erythritol tetranitrate (Vol. II). On the basis of these facts the author suggests that two main reasons are responsible for the formation of these addition compounds ... 

Figure 72 shows the influence of trinitrotoluene on the rate of nitration of dinitrotoluene in heterogeneous systems at 90°C. It is interesting to note that the addition of 66-70% of trinitrotoluene to dinitrotoluene more than halves the rate of the nitration, Further increase in the content of trinitrotoluene promotes nitration of dinitrotoluene. When the content of trinitro compound reaches 91% the yield of trinitration is almost the same as that of the pure dinitrotoluene. 

Robertson [113a], however, reported that the sensitiveness of picric acid at 80°C is only 25% greater than that at 15°C. This may well be extended to other trinitro compounds, so it would be expected that the increase in sensitiveness of TNT with increasing temperature is less significant than that given by Rinkenbach. 

The starting product is nitrated with anhydrous nitric acid (sp. gr. 1.52) to the trinitro compounds. The methoxy group of the latter, on boiling with ammonia in methyl alcohol, can be substituted by an amino group. 

For further purification molten TNT and hot water in equal volumes are run into a cast iron tank of 15 m3 capacity, where the TNT is emulsified by vigorous stirring. The emulsion is cooled to 74-76°C and treated with a 25% solution of sodium sulphite, used in such a proportion as to obtain a final concentration of sodium sulphite in the mixture of 2.5%. During the sulphitation process 5-6% of trinitro compounds and 0.2-0.3% of tetranitromethane (calculated on the TNT) go into solution. 

At first o- xylene was believed (Noelting and Thesmar [16]) to be without trinitro derivatives, until Crossley and Renouf [17] obtained a trinitro compound,... 

During World War II a method of preparing mixtures of nitro compounds (e.g. TNT and TNX, or TNT and tetryl, see Vol. IV) was developed by the Germans. It consisted in the nitration of the corresponding lower nitrated compounds, namely a mixture of mononitrotoluenes plus mononitroxylenes was nitrated in two stages to form trinitro compounds. In this way a product containing 20% of TNX and 80% of TNT was obtained. 

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