Polynitro thermal decomposition

A sample of the compound exploded violently after short heating to 100°C. Although this was attributed to presence of polynitro derivatives [1], the thermal decomposition of this type of nitro compound is known [2]. 

Regarding the 1,3-diazocines, it was reported that the synthesis of the left domain of haplophytine, a hetero-dimeric alkaloid endowed with insecticidal activity, contained a pyrrolo-fused carbonyl bridged 1,3-benzodiazocine moiety <2007AG(E)4715>. It was also reported that the synthesis of a pyrazolo-fused 1,3-benzodiazocine and its activity as inhibitor of lymphocyte-specific protein tyrosine kinase (Lck) <2007W0026720>, and the thermal decomposition of a polynitro substituted 1,3-diazocine <2006RJGC499>. 

BASIC MECHANISMS OF THERMAL DECOMPOSITION OF ORGANIC POLYNITRO AND POLYNITROSO COMPOUNDS... 

In the coordinate system shown in Fig. 5, the set of polynitro arenes studied falls into several classes. Classes A and C contain compounds characterised by the trinitrotoluene mechanism of primary fission in their thermal decomposition. Class B represents unsubstituted polynitro arenes (TNB, HNB and NONA) with primary homolysis of C-NO2 bond in their thermal decomposition. Correlation of HNS data with this Class may be a coincidence but it may also be a result of intermolecular interaction in its crystals. Class D contains dipicryl derivatives in which the intermolecular interaction should dominate the influence on their reactivity (primary fission by heat in NONA is different from that in DIPS). The said influence occurs occasionally in larger molecules with strong intermolecular interactions and was observed in some cases of decomposition initiated by impact [36,75], electric spark [35,36] and (depending on the measurement method applied) also heat [102]. 

On the other hand, the characteristics of detonation, electric spark sensitivity, and thermal decomposition correlate with the N NMR chemical shifts of nitrogen atoms of the most reactive nitro groups. The basis of initiation by electric spark could lie in a thermal stimulus [35,39,52,53]. However, thermal stimuli cannot be considered in the process of detonation initiation by shock (also by impact) [115]. This also agrees with the finding that the detonation characteristics of energetic materials correlate with the characteristics of their low-temperature decomposition, which means that the primary fragmentation of polynitro compounds in their detonation transformation proceeds at milder conditions than those present at the front of detonation wave or in its reaction zone. That also means that the detonation transformation itself of the given substance should be preceded by an induction period [120]. 

The chemical micro-mechanisms of primary fission processes in molecules of polynitro compounds during initiation by mechanical stimuli (inclusive of the detonation course) and electric spark should be the same as in the case of their low-temperature thermal decomposition. In the case of initiation of nitramines by impact and shock, an excellent agreement in this respect was also found with the results of molecular-dynamic simulation by Kohno et al. [27]. The more complex molecular structure of polynitro arenes makes the problem of their primary fission somewhat complicated, too. If a molecule of these compounds contains several types of substituents, it can contain several potential reaction centres (e.g. the TMPM and PYX molecules). The initiation proper can then be realised by the molecule simultaneously participating by... 

Scheme 2 Trinitrotoluene mechanism of thermal decomposition of polynitro arenes with a hydrogen atom in the y-position towards the nitro group - here X can be CH, CH2, O, N, or S in the case of TNT, the last fragment forms 4,6-dinitro-2,l-benzoisoxazole and other decomposition products [11] in the case of amino derivatives (X = NH2) derivatives of 4,6-dinitrobenzofurazans and furoxans result...

Fig.2 Graphical representation of the relationship between activation energies, E, of low-temperature thermal decomposition and NMR chemical shifts of polynitro arenes (the numbers in parenthesis denote the position in the molecule) a general scheme of the primary step of chemical decomposition is presented with each line [150]...

The polynitro compoimds in Fig. 15 fall into three classes. Each of them includes compounds with a characteristic range of values for thermolysis rate constants at their onset temperature of exothermic decomposition [166]. The given temperatures result from differential thermal analyses of the said compounds. This finding corresponds with the known relationships between impact sensitivities and thermal decomposition characteristics of polynitro compounds [16,89,148]. This means that some relationship exists between... 

Figure 20 has been taken from [9] and presents Eq. 8 in which the Ea values resulted from the Russian manometric method for polynitro arenes and Qreai values were calculated according to the Pepekin et al. semi-empirical method [157]. It must be stated that the value of TATB, obtained on the basis of the Russian manometric method (i.e. in vacuum, see [151]) in a temperature region above its hypothetical melting point [171], correlates with the data for thermal decomposition in the Uquid state (this Ea value, which is very close to the heat of sublimation of TATB, is discussed in [171]). The data of TATB obtained from DSC (see [151], i.e. from measurements at atmospheric pressure) logically correlate with DATB and PAM data in Fig. 20. 

Fig. 20 Graphical representation of the modified E-P-S equation (Eq. 8) [9] for polynitro arenes with a hydrogen atom at the y-position with respect to the nitro group (Scheme 2) exceptional are the polychlorinated derivatives of 1,3,5-trinitrobenzene—TNB (i. e. CTB, DCTB, and TCTB) whose thermal decomposition, however, represents a certain analogy with the decomposition of polymethyl derivatives of TNB [9]...

Brill, T.B. and Oyumi, Y. (1986) Thermal Decomposition of Energetic Materials 10. A Relationship of Molecular Structure and Vibrations to Decomposition Polynitro-3,3,7,7-tetrakis (trifluoromethyl)-2,4,6,8-tetraazabicyclo[3.3.0]octanes Journal of Physical Chemistry 90, 2679-2682. 

Polynitro derivatives of monocychc aromatic systems (trinitrobenzene, trinitrotoluene, tetranitro-iV-methylaniline, trinitrophenol, etc.) have long been used as explosives [1]. It has been found that a series of polynitroderivatives of biphenyl, diphenylmethane and 1,2-diphenylethylene (stilbene) are explosives liable to detonate on grinding or impact [2]. The same may be true of other polynitro derivatives of polycyclic systems not normally used as explosives (e.g. polynitro-fluorenones, -carbazoles, etc. Penta- and hexa-nitrobenzophenones are also high-energy explosives [3]. The thermal stability of 33 polynitroaromatics was studied by DTA [4]. Two empirical equations relating the heat of decomposition to the heat of detonation have been developed and used to calculate the heats of detonation for 47 polynitroaryl compoimds [5]. 

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