Nitroaromatic compounds explosives

Explosives for Use at High Temperatures. Explosives that can withstand prolonged exposure to elevated temperatures without detonating find considerable use ia such appHcations as detonators for deep oil wells, space travel, and componentry for specialised appHcations. The explosives developed for this purpose are primarily nitroaromatic compounds, the most important of which are hexanitrostilbene and... 

Even though some nitroaromatic compounds are purposefully spread in the environment as pesticides, the majority of their environmental releases are accidental. For example, in the United States alone, 5.1 tons of nitrobenzene were released in soil in 2002 [65]. The greatest known industrial releases have occurred in China in 2005, an explosion at a chemical factory resulted in the accidental release of 100 tons of benzene and nitrobenzene to the Songhua River [66]. 

An important demonstrated application of this artificial nose system is the high-speed detection of low levels of explosives and explosive-like vapors. Several sensors, based on Nile Red attached to silica microspheres, show high sensitivity to nitroaromatic compounds (NAC) within a mixture12. Different fluorescence response profiles were observed for several NAC s, such as 1,3,5-trinitrotoluene (TNT) and 1,3-dinitrobenzene (DNB), despite their similar structures. These responses were monitored at low concentrations of the NAC vapors (ca. 5 ppb) and at short vapor exposure... 

Kim TH, Kim HJ, Kwak CG, Park WH, Lee TS (2006) Aromatic oxadiazole-based conjugated polymers with excited-state intramolecular proton transfer their synthesis and sensing ability for explosive nitroaromatic compounds. J Polym Sci A Polym Chem 44 2059-2068... 

It is possible to quantify individual nitroaromatic compounds present in commercial nitroglycerine-based explosives without prior separation, by using 500 MHz NMR. Patterns within the quantitative data provide a good degree of sample batch characterization447. 

It is widely stated in the usual reference texts that nitroaromatic compounds and more particularly polynitroaromatic compounds may present a severe explosion risk if subjected to shock, or if heated rapidly and uncontrollably, as in fire... 

Burken, J. G., Shanks, J. V. and Thompson, P. L., 2000, Ph)4oremediation and plant metabolism of explosives and nitroaromatic compounds, in Biodegradation of Nitroaromatic Compounds and Explosives, J. C. Spain, J. B. Hughes, H. J. Knackmuss, eds., Lewis Publishers, Boca Raton, pp. 240-275. 

Although most color tests for polynitroaromatic explosives are based on their reaction with bases, a completely different approach involves the reduction of nitroaromatic compound to the corresponding aromatic amine. Zn, SnCl2, and TiCls in acidic medium were used as reducing agents [23—26]. The aromatic amine is then identified by one of two methods ... 

This relationship also conveys one of the reasons why the sensing of explosives can be so effective with this method. Most explosives, especially TNT and other nitroaromatic compounds, are highly electron deficient and have favorable reduction potentials. For instance, the reduction potential of TNT and DNT are only —0.7 and—1.0 V (versus SCE) respectively, quite favorable when compared with other electron acceptors, such as 1,4-dicyanobenzene (—1.7 V versus SCE). This means that if the sensory material emits hght, for example, at 460 nm, the oxidation... 

When explosives are found singly or as mixtures there is a problem of their rapid identification. It is particularly significant in field areas where normal laboratory facilities are not available and unknown explosives have to be quickly characterized. Though the n complexes of nitroaromatic compounds with hydrocarbons have been studied by TLC [5], yet suffer from the disadvantage of their colorless nature and difficulty of location on the chromatoplates... 

Contamination by nitroaromatic compounds, especially TNT, stems primarily from military activities (Boopathy et al., 1994). During the manufacture of explosives and the disposal of old munitions, large quantities of water became contaminated. This wash water was typically disposed of in unlined lagoons that facilitated the slow release of the explosives from the soil in the lagoons into groundwater, lakes, and rivers. 

Until very recently, explosives-contaminated soils have been remediated by incineration, a process whose high cost has stimulated the search for a more economical cleanup method (Roberts et al., 1993). Microbially mediated degradation of explosives is a promising technology. Many researchers have studied microbial consortia and various pure cultures for their ability to degrade TNT and other nitroaromatic compounds (for a review see Crawford, 1995), bringing about the development of bioremediation processes that can remove TNT and other explosives from contaminated soil and water (Funk etal., 1995 Williams a/., 1992). 

Nitroaromatic compounds (NACs) are one of the widespread contaminants in the environments. Sources of NACs are numerous they originate from insecticides, herbicides, explosives, pharmaceuticals, feedstock, and chemicals for dyes (Agrawal and Tratnyek, 1996). Under anaerobic conditions, the dominant action is nitro reduction by zero-valent iron to the amine. Other pathways do exist, such as the formation of azo and azoxy compounds, which is followed by the reduction of azo compounds to form amines. Also, in addition to the possibility of azo and azoxy compounds, phenylhydrox-ylamine may be an additional intermediate (Agrawal and Tratnyek, 1996). Nitrobenzene reduction forms the amine aniline. Known for its corrosion inhibition properties, aniline cannot be further reduced by iron. Additionally, it interferes with the mass transport of the contaminant to the surface of the iron. The overall reaction is as follows ... 

Several industrial explosions have occurred during the past 40 years which appear to be attributable to this cause, but here has been little recognition of this or of the common features in many of the incidents. Too little investigational work in this area has been published to allow any valid conclusions to be drawn as to the detailed course of the observed reactions. However, it may be more than coincidence that in all the incidents reported, the structures of the nitroaromatic compounds involved were such that o- or p-aci-nitroquinonoid salt species could have been formed under the reaction conditions. Many of these salts are of very limited thermal stability. All of the available (circumstantial) evidence was collected and published [4]. Limited work by... 

Nitrogen-explosive compounds usually analysed by CL may be classified under three structural categories (i) nitroaromatic compounds, (ii) nitrate esters and (iii) nitramines. Examples of nitro-substituted hydrocarbons are nitromethane, trinitrobenzene (TNB), trinitrotoluene (TNT) and pentantiroaniline. Nitroglycerine (NG), ethylene glycol dinitrate (EGDN) and pentaerythritol tetranitrate (PETN) are nitrate esters [5], The nitro-explosive compounds that are the result of the presence of nitro and nitrate groups can... 

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