Explosive nitroarenes

Nitrotoluenes including 2,4,6-trinitrotoluene (TNT) are important components of explosives and several nitroarenes including the antibacterial nitrofurans have established mntagenicity (Purohit and Basu 2000). Substantial effort has been directed to the degradation of nitroarenes, and to their reduction to amines. Although nitroarene reductases, noted in Chapter 3, Part 3, are distribnted in a range of biota, the products may not necessarily represent intermediates in the degradation... 

The most famous explosive is trinitrotoluene, or TNT, which was mainly used in warfare in both world wars, as well as in mining and building. TNT is still widely used and produced. Most of the current problems with TNT and nitroarene compounds are found in sites where ammunition was handled, stored or manufactured. TNT is a persistent contaminant, but its microbial degradation is possible both aerobically [63] and anaerobically [64]. 

The catalytic effect of tetra-n-butylammonium fluoride in the homogeneous reduction of heterocyclic A-oxides and nitroarenes by hexamethyldisilane in tetra-hydrofuran can occur with EXPLOSIVE violence, but can be controlled by the slow addition of the disilane to the A-oxide (or nitroarene) and tetra-n-butylammonium fluoride to yield the parent heterocycle (>70%) (or azobenzene 84%). In a similar manner, azoxybenzene is converted into azobenzene (95%), and 4-nitropyridine-l-oxide, is reduced to azoxypyridine-l,l -dioxide (78%), with minor amounts of azopyridine-1, l -dioxide and azopyridine-1-oxide [5,6]. 

The chemical structures of some common mifttary explosives are shown in Figure 1. These include the nitrate esters such as nitrocellulose (NC), NG, EGDN, and (PETN) nitroarenes such as trinitrotoluene (TNT, CH3—C6H2(N02)3), picric acid (HO—C5H2(N02)3), and 2,4,6-trinitrophenylmethylnitramine (tetryl) and nitramines such as RDX (C3H6N6O6), HMX (C4H8N8O8), and hexanitrohexa-azaisowurtzitane (CL— 20). Of these, only CL— 20 is new , that is, less than 50 years old [3]. Mixtures of oxidizers and fuels, such as AN and FO (called ANFO), are also secondary explosives. 

The nitroarenes, picric acid and TNT, have been used as explosives since the late 1800 s (Fig. 3). At temperatures over which the thermal stability... 

C. Oxley, .L. Smith, W. Wang, "Compatibility of Ammonium Nitrate with Monomolecular Explosives, Part I," . Phys. Chem., 98 (1994) 3893-3900. .C. Oxley, .L Smith, W. Wang, "Compatibility of Ammonium Nitrate with Monomolecular Explosives, Part II Nitroarenes," . Phys. Chem., 98 (1994) 3901-3907. 

Reduction of nitroarenes to aminoarenes (1, 440-441). Du Pont chemists have reported an explosion during attempted reduction of 2-chloro-5-methyl-nitrobenzene to the amine by hydrazine and Pd-C. The main product was shown to be 2-chloro-5-methylphenylhydroxylamine arylhydroxylamines are known to decompose violently when heated over 90-100°. 

Tetrakis(4-pyridyl)porphyrin was covalently linked to GO and electrochemical reduction of explosive nitroaromatic compounds was obtained by the hybrid, thus performing detection of ultra-trace explosives [121]. Comparing the sensitivity and detection limit of various electrochemical sensors toward TNT detection, the resulting porphyrin/graphene-modifled GC electrode was of superior quality, allowing detection of 0.5 ppb. Detection limit for other nitroarenes were 1 (2,4-dinitrotoluene), 1 (1,3,5-trinittobenzene) and 2 (1,3-dinitrobenzene) ppb, respectively. 

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