Tetrazine explosives

Z. Xizeng and T. Ye, Synthesis and Properties of Tetrazine Explosives , in Proc. International Symposium on Pyrotechnics and Explosives, China Academic Publishers, Beijing, China, 241 (1987). 

Tetrazine explosive Tetrazine Separated on ion-pairing reverse phase column and UV detection at 280 nm... 

Pagoria and co-workers synthesized a number of thermally stable explosives from the reaction of the sodium salt of ANTA with chloro-substituted arylenes and A-heterocycles. These include the synthesis of (117) from picryl ehloride, PRAN (118) from 2-chloro-3,5-dinitropyridine, IHNX (119) from 2,4-dichloro-5-nitropyrimidine, (120) from 1,5-dichloro-2,4-dinitrobenzene, and (121) from 4-chloro-6-(3-nitro-l,2,4-triazolyl)-5-nitropyrimidine. Coburn and co-workers " reported the synthesis of the tetrazine (122) and the triazine (123) from the reaction of the sodium salt of ANTA with 3,6-dichlorotetrazine and cyanuric chloride respectively. 

Tetrazine-based explosives are often highly energetic. The high nitrogen content of such compounds often results in high crystal density and explosive performance. 3,6-Diamino-1,2,4,5-tetrazine (198) is a starting material for the synthesis of other 1,2,4,5-tetrazines and is itself synthesized from the condensation of triaminoguanidine hydrochloride (195)... 

The chemical uses of diazoazoles can be divided into two classes. The first, actually very limited, involves the applications of the diazo compounds themselves. The second one implies the use of the diazoazoles as key intermediates for the synthesis of biologically interesting systems such as triazenes, azolo-triazines and azolo-tetrazines, and azo dyes, which are useful in photographic processes or in the texile industry. 2-Diazo-4,5-dicyanoimidazole has found application as an explosive (73USP3770764). 

A new area of research and activity in recent years is the development of new explosives based on furazans, furoxans and tetrazines in order to achieve an increase in density, stability, insensitivity and velocity of detonation. As a result, a number of prospective HEMs which are potential ingredients of explosive, propellant and pyrotechnic formulations have been synthesized. 

Chavez and Hiskey continued their research on 1,2,4,5-tetrazine-based explosives and synthesized a number of derivatives which are considered interesting as propellant or smoke-free pyrotechnic ingredients because of their low carbon content, high heat of formation and a density of-1.61 g cm4. One such compound is 3,6-dihydrazino-l,2,4,5-tetrazine which appears to be an important energetic fuel [275, 276]. 

These compounds exhibit very low pressure-dependence during combustion and the compound [3,6-bis(nitroguanyl)-l,2,4,5-tetrazine] in particular, shows the lowest pressure exponent known in the literature for a neat material. Further, the interesting combustion behavior of these explosives make them suitable for gasgenerating and propellant applications [288]. 

The following uses have been claimed for compounds containing the 1,2,4,5-tetrazine skeleton as herbicides, insecticides, bactericides, as pharmaceuticals, as explosives and rocket propellants, as photographic dyes and additives to photographic layers, as reducing agents, as inhibitors of steel corrosion and as fuel additives. 

Primary explosives include mercury fulminate [Hg(ONC)2, melting point 160°C with explosion, density 4.2], lead azide [Pb(N3)2, density 4.0], basic lead styphnate (lead trinitroresorcinate), diazodinitrophenol, and tetrazine (a complex conjugated nitrogen compound, melting point 140 to 160°C with explosion). Most priming compositions consist of mixtures of primary explosives, fuels, and oxidants. 

Explosives are classified as primary or secondary, based on their susceptibility to initiation. Primary explosives, which include lead azide and lead styphnate, are highly susceptible to initiation. Primary explosives often are referred to as initiating explosives because they can be used to ignite secondary explosives. Secondary explosives, which include 2,4,6-trinitrotoluene (TNT), hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX or cyclonite), high melting explosives (HMX) like octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazine (HMX),... 

Using an expert computer program developed to identify high explosives, the heat of formation of the 4,6-dioxide of [l,2,5]oxadiazolo[3,4-e][l,2,3,4]tetrazine (2 X = 0) has been calculated <92MI 714-01). 

Fig. 9.23 Explosion of bis(trinitroethyl)-l,2,4,5-tetrazine-3,6-diamine (BTAT) in Koenen test.

Most reports are published in patents, and only a few in scientific journals. Nevertheless a few remarks may be made on the use of tetrazine derivatives or their hydrogenated forms as pharmaceuticals, pesticides, liquid crystals, explosives, and propellants. 

A BKW equation of state in a one-dimensional hydrodynamic simulation of the cylinder test can be used to estimate the performance of explosives. Using this approach, the novel explosive 3,6-diamino-l,2,5,6-tetrazine 1,4-dioxide has been analyzed . 

Traditionally, tetrazines attract attention as energetic materials in the development of explosives. This year, first members of a new class of electroactive explosives based on nitrate ester-functionalized 1,2,4,5-tetrazines... 

The synthesis and properties of several high-nitrogen materials with 3-amino-6-nitroamino-tetrazine (ANAT) as the anion are reported (Scheme 23). These salts (99, 100, 103a,b) provide a new and easy approach to highly energetic salts. All these salts are relatively dense (> 1.55 g/cm ) and exhibit good thermal stability T > 148 C). The calculated detonation velocities and detonation pressures are comparable to those of explosives such as Tetryl, PETN, TATB, and RDX. A combination of theoretical and empirical calculations shows that all these salts have high molar enthalpies of formation (Table 9) [99]. 

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