Trinitrotoluene mechanism, thermal

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]. 

An application of such approach to studies of detonation mechanism of the arenes studied is hindered by a serious problem the unavailability of NMR spectra of most of them. An analogous application of the easily available C NMR chemical shifts of the bearers of the most reactive nitro groups in their molecules is limited. In the case of unsubstituted polynitro arenes this application does not provide any useful relationships (the primary fission should consist in the homolysis of C-NO2 bond). However, for derivatives of the said compounds it is possible to find reliable relationships if the nitro group in the reaction centre of molecule stands in perfect mesomeric interaction with the 7t-electron system of nucleus at the moment of formation of the transition state (see Scheme 2). This means that this group participates in the primary fission by one of its oxygen atoms (the trinitrotoluene mechanism of thermal... 

Scheme 2. Presumed mechanism of electron shifts at the beginning of low-temperature thermal decomposition of 3,3 -dimethyl-2,2, 4,4, 6,6 -hexanitrodiphenylsulfide with participation of nitro group at 2-position in the reaction center (typical trinitrotoluene mechanism - left formula) and with participation of nitro group at 6-position in the reaction center (right formula - real pathway of the fission).

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...

Schemes a Theoretical, less probable mechanism of electron shifts at the beginning of the low-temperature thermal decomposition of 2,4,6-trinitro-3-[(3-methyl-2,4,6-trinitrophenyl)thio] toluene (DMDIPS) with participation of the nitro group at the 2-position in the reaction centre (typical trinitrotoluene mechanism ) [6,148). b Presumed...

E. Neal, Jr et al, Effects of Thermal Cycling on Trinitrotoluene (TNT) and Tritonal Explosive Compositions , AFATL-TR-79-15, Rept WQEC/C 79-111 (1979) (limited dis-trib) 109) Di7. McMillen et al, Kinetics and Mechanisms of the Gas-Phase Decomposition of Nitroaromatics , ACS mtg, Honolulu (April 1979) 110) S. Bulusu, JOrgMassSpec... 

The explosive properties of the compound TX differ considerably from those Of trinitrotoluene. Its explosive power is much lower than that of trinitrotoluene, which may be explained by the smaller number of the nitro groups present. Both T acid itself, and also its salts, are much more sensitive to mechanical and thermal stimuli than trinitrotoluene. 

Current processes for the manufacture of trinitrotoluene (TNT) produce atmospheric and water pollution that is only partly relieved by mechanical clean-up methods. TNT is currently produced from toluene by successive mono-, di-, and trinitrations with mixed aqueous nitric and sulfuric acids in the first two steps and anhydrous mixed acid in the last. Each stage in the current process is conducted at elevated temperatures, and side reactions in the overall process directly produce thousands of pounds of oxides of nitrogen, sulfuric acid aerosols, and volatile nitro organic products (such as tetranitromethane and nitroaro-matics). These pollutants derive from the thermal decomposition of the aqueous nitric acid solutions, from oxidative side reactions that produce as many as 40 by-product compounds, and from formation of unsymmetrlcal "meta" Isomers. Since symmetrical TNT is inevitably accompanied by meta isomers as well as oxidation products, the crude material is treated with sodium sulfite solutions to remove the undesirable Isomers and nitroaromatics by derivatization. The spent sulfite solution, known as "red water, is then disposed of by combustion to an inorganic ash. Itself a disposal problem. 

Boron-doped diamond presents another attractive material with low and stable background current and noise over a wide potential range, corrosion resistance, high thermal conductivity, and high current densities. Usually no mechanical or electrochemical pretreatment of BDD film electrode is needed. Therefore, BDD film electrodes find use also in the area of environmental analysis for organic explosive determinations. BDD-based electrochemical detector allowed, e.g., amperometric detection of 2,4,6-trinitrotoluene, 1,3-dinitrobenzene, and 2,4-dinitrotoluene over the 200-1,400 ppb range, with detection limits at the 100 ppb level. ... 

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