Peroxide-based explosives

For over 20 years two improvised explosives containing the peroxide group have been of constant concern to legal authorities. Both triacetonetriperoxide (TATP) (2) and hexamethylenetriperoxide diamine (HMTD) (3) are easily prepared from readily available starting materials. Both compounds have been encountered for the first time by the Israel Police in the late 1970s and early 1980s [60], but 

Because of their ease of preparation and extreme sensitivity, the two peroxides have become a great threat to law-enforcement agencies. To assist the development of optimal defensive measures, they have been studied by several research groups and their analytical properties, physical characteristics, and explosive properties have been thoroughly explored [64-84]. 

The authors report detection limits of 8x10 ° mol/dm for TATP and 8 X lO mol/dm for HMTD. When p-hydroxyphenylacetic acid (p-HPAA) (6) was used as the oxidation substrate instead of ABTS, a highly fluorescent dimer (7) was formed. This dimer could be detected spectrophotometricaUy, although the sensitivity dropped (Eq. (12)). Both methods also enabled a semi-quantitative estimation of TATP and HMTD concentrations [86]. Dimerization of p-hydroxyphenylacetic acid (p-HPAA) by hydrogen peroxide in presence of peroxidase [86] is as foUows  

A non-enzymatic color reaction for TATP and other organic peroxides was reported recently by Apblett et al. [87, 88]. The dark blue color of molybdenum hydrogen bronze suspension is changed to yellow upon oxidation with TATP. The same reagent can also be used for quick neutralization of the sensitive explosive a lasting final blue color indicates complete neutralization. The reaction with TATP is depicted in Eq. (13). 

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Colorimetric field tests for TATP and HMTD were described in Section 5 dealing with peroxide-based explosives. This group contains Keinan s PEX [85] (E. Keinan, Personal Communication, February 2006) and the kit developed by Schulte-Ladbeck et al., which involves also a preliminary stage to avoid falsepositive responses by non-explosive peroxides [86]. The color change of molybdenum hydrogen bronze suspension upon reaction with TATP was recommended also as a field test. Exposure of filter paper strips which were soaked in butanol suspension of the molybdenum compound to TATP or hydrogen peroxide vapors rapidly bleaches the blue color [87, 88]. 

The Fido sensor is an extremely sensitive and selective detector for nitroaromatic explosives such as TNT. The sensor has also been shown to detect most smokeless powders and black powders. Work is now underway to develop polymers that enable detection of nitramine explosives, such as RDX and HMX. Recently, a new polymer was tested that shows promise for detection of the taggant dimethyldinitro butane (DMNB). Development of polymers for detection of peroxide-based explosives is also planned. 

Even smaller than the handheld devices above is a newly developed pen-like device which can detect sub-milligramme amounts of peroxide-based explosives . The prototype costs less than 23 per unit. A suspect sample is placed on a silicone rubber test pad. Three test chemicals are sequentially injected into the transparent chamber in the pen and a blue-green colour change occurs on reaction with any peroxide present in the sample within three seconds. 

Milgrom, L. Pen detects peroxide-based explosives. Chemistry World, July 2005, 7. 

In July 2005, London was subjected to a series of terrorist attacks Bombs exploded on the public transport network at rush hour. Three bombs were detonated on trains in the London Undergroimd and one was detonated on the upper deck of a bus. It was initially thought that military-grade plastic explosives had been used in the attack on 7 July because it appeared that the explosions had been synchronised. However, it was later determined that the bombs were homemade devices consisting of triacetone triperox-ide (TATP). TATP is a peroxide-based explosive that is highly susceptible to shock, heat, and friction and is one of if not the most sensitive explosives known (Bubnikova et al. 2005). 

Peroxide-based explosives, such as TATP, diacetone diperoxide (DADP), and hexamethylene triperoxide diamine (MHTD) can be detected using HPLC-DAD at 214 nm (see Figmes 11.5 and 11.6). Successful LC-MS/MS of explosives has been reported, as has the use of ion mobility and liquid chromatography with amperometric detection (Vigneau and Machuron-Mandard 2009 Hilmi et al. 1999 Ou et al. 2009 Meng et al. 2008). 

Fig. 12.13 (a) Molecules used to show the sensing application the dimer top) and trimer bottom) of acetone peroxide, (b) Graphene ribbon used as sensor material of acetone peroxide based explosives (Reprinted from Ref. [38] with kind permission of The American Institute of Physics)... 

Oxley, J., Smith, J., Brady, J., Dubnikova, R, Kosloff, R., Zeiri, L., Zeir, Y. (2008). Raman and Infrared Fingerprint Spectroscopy of Peroxide-Based Explosives Society for Applied Spectroscopy. 62, 906-915. 

Schulte-Ladbeck, R., Kolia, P., Karst, U. Trace analysis of peroxide-based explosives. Anal. Chem. 75, 731-735 (2003)... 

Another peroxide-based explosive is hexamethylene triperoxide (HMTD), which, again, can be made simply and cheaply from common liquids (hydrogen peroxide, hexamine and citric acid). It, too, is extremely sensitive to shocks, heat and friction, and can detonate when put into contact with most common metals, which makes it very dangerous to make under non-lab conditions. HMTD (along with TCAP) were implicated in the 2006 transatlantic aircraft bomb plot, in which terrorists aimed to blow up 10 airliners traveling between the United Kingdom and... 

Perchlorate explosive mixtures Peroxide-based explosive mixtures PETN (nitropentaerythrite, pentaerythrite tetranitrate, pentaerythritol tetranitrate) Picramic acid and its salts Picramide... 

Amine Peroxides as Explosives. Some amines may yield expl peroxides. For instance, hexamethylenetetramine when treated with hydrogen peroxide in the presence of an organic add(citric) which combines with the liberated Nris, forms hexamethylenetriperoxidediamineiqv) (Ref IX Schif f s bases, ammoniacal aldehydes or their... 

The most difficult aspect of the method is the fact that it is based on the handling of compounds that unequivocally belong to the family of powerful explosives. There is no doubt that working with peroxide compounds is dangerous and requires the development and implementation of special procedures and safety equipment. 

Addition of 30% peroxide and sulfuric acid to 2-methylpyridine and iron(II) sulfate caused a sudden exotherm, followed by a vapour phase explosion and ignition. Lack of stirring is thought to have caused local overheating, vaporisation of the base and its ignition in the possibly oxygen-enriched atmosphere. 

Hydroxylamine is a powerful reducant, particularly when anhydrous, and if exposed to air on a fibrous extended surface (filter paper) it rapidly heats by aerobic oxidation. It explodes in contact with air above 70°C [1]. Barium peroxide will ignite aqueous hydroxylamine, while the solid ignites in dry contact with barium oxide, barium peroxide, lead dioxide and potassium permanganate, but with chlorates, bromates and perchlorates only when moistened with sulfuric acid. Contact of the anhydrous base with potassium dichromate or sodium dichromate is violently explosive, but less so with ammonium dichromate or chromium trioxide. Ignition occurs in gaseous chlorine, and vigorous oxidation occurs with hypochlorites. 

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