Nitroguanidine decomposition

With primary nitramine sulphuric acid may promote the separation of nitric acid, which results in extensive decomposition of the substance. This will be discussed in more detail when dealing with nitroguanidine (p. 26). 

This substance is an intermediate product of the decomposition of the important explosive nitroguanidine. It is also present in an aqueous solution of nitrourea or a sulphuric acid solution of nitrourea (Davis and Blanchard [7]). 

Nitroguanidine has weakly basic properties and this accounts for its ability to form salts with concentrated acids, e.g. it forms a sulphate with concentrated sulphuric acid. Nitroguanidine is hydrolysed on heating with concentrated sulphuric acid evolving nitrous oxide and carbon dioxide, the former probably derived from hydrolysis of nitramine and the latter from hydrolysis of cyanamide. The latter also yields ammonia on decomposition. 

The decomposition of nitroguanidine by the action of ammonia in aqueous solution also proceeds according to equations (19) and (20). 

Barton, Hall and Wright [42] found that the action of alkalis on nitroguanidine involves hydrolysis with the formation of ammonia, nitrourea and the products of the decomposition of nitrourea. 

Nitroguanidine demonstrates high stability in aqueous solution on boiling, but on long-continued boiling evolves small amounts of ammonia, possibly due to decomposition according to equation (22) ... 

According to equation (19) decomposition also occurs on boiling nitroguanidine in an aqueous solution of ammonium carbonate, with liberation of nitrous oxide and ammonia. The latter combines with the cyanamide also resulting from reaction (19) and guanidine carbonate is formed in almost quantitative yield. 

In the presence of primary aliphatic amines in aqueous solution nitroguanidine undergoes decomposition according to equation (22). Ammonia is then evolved, and nitrocyanamide combines with the amine to form alkylnitroguanidine, e.g. N-methyl-N -nitroguanidine ... 

Attention has been paid to nitroguanidine as an explosive since Vieille [28] found that the gases from the decomposition of nitroguanidine are less erosive than those from the decomposition of other explosives of comparable power (Table 4). 

Such a low temperature of explosion was very surprising and the author appears to have been in doubt as to its validity. Indeed, Muraour and Aunis [56] have shown that the temperature of explosion of nitroguanidine may, in fact, be much higher. They pointed out that nitroguanidine ignites with difficulty and undergoes incomplete explosive decomposition. That is why the explosion temperature, as reported by Patart, is so low. 

Taking into account the results of experiments conducted with a manometric bomb as well as the chemical composition and specific heat of the products of decomposition Muraour and Aunis calculated the following values for the explosion of nitroguanidine ... 

Both a- and /3-nitroguanidine, if dissolved in hot concentrated nitric acid and allowed to crystallize, yield the same nitrate, thick, rhomb-shaped prisms which melt at 147° with decomposition. The nitrate loses nitric acid slowly in the air, and gives a-nitroguanidine when recrystallized from water. Similarly, both forms recrystallized from strong hydrochloric acid yield a hydrochloride which crystallizes in needles. These lose hydrogen chloride rapidly in the air, and give a-nitroguanidine when recrystallized from water. The two forms are alike in all their chemical reactions, in their derivatives and color reactions. 

Many of the reactions of nitroguanidine, particularly its decomposition by heat and the reactions which occur in aqueous and in sulfuric acid solutions, follow directly from its dearrangement.13 Nitroguanidine dearranges in two modes, as follows. 

Flashless colloided powder containing nitroguanidine produces a considerable amount of gray smoke made up of solid materials from the decomposition of the substance. The gases smell of ammonia. The powder produces more smoke than the other flashless powders which are used in this country. 

This assumption however is not true, for powder which contains nitroguanidine produces a gray smoke consisting of solid decomposition products and yields gases which smell of ammonia. 

Mass spectra of the important explosives RDX, HMX, TNT, TNB and Tetryl were first briefly reported by Meyer (Ref 34) and later investigated in greater detail with high resolution and labeling techniques by Bulusu et al (Ref 45). Mass spectrometric studies of the photodecomposition of labeled dimethyl-nitramine (Ref 56) and the thermal decomposition of HMX and RDX (Refs 27 31) illustrate the application of these techniques to studies of reaction mechanism and bond dissociation processes. Nitroguanidines have only recently been investigated by Beynon (Ref 35)... 

The crystal structure of the potassium salt of l-(tetrazol-5-yl)-2-nitroguanidine [K(C2H3N802)] was solved and refined from laboratory X-ray powder diffraction data by applying the DDM decomposition and refinement methods. The structure model was found from a Patterson search, for which the reflection intensities were derived from the powder profile by the DDM decomposition. The use of DDM allowed successful location and unconstrained refinement of all the atomic positions, including those of three... 

Light and heat and can cause decomposition. May react violently or form sensitive explosive compounds with 2-butyne-l,4-diol, fluoroacetylene, a-nitroguanidine, 5-nitrotetrazol, and others. Incompatible with ammonia, hydrozoic acid, methyl isocyanoacetate, sodium acetylide, sodium peroxyborate, trinitrobenzoic acid, urea nitrate. 

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