Insensitive high explosives

Common explosives like TNT, RDX and HMX were considered adequate for all weapon applications, but these explosives have now become less attractive due to a number of accidents involving initiation of munitions by impact or shock aboard ships, aircraft carriers and ammunition trains. So there is a trend of current research worldwide to synthesize explosives which have high performance coupled with low sensitivity. 

Reprinted with permission from A.B. Sheremetev and T.S. Pivina, Proc.27th Inti. Ann. Conf. 1 996, p30/6 1996, ICT, Karlsruhe, Germany. 

TATB is well-known for its insensitivity and is currently employed as an IHE for some applications. TATB is however, inferior to RDX and HMX in performance. Therefore, a need exists for the research and development of explosives that are powerful yet resistant to accidental and sympathetic initiation. 

Norris and co-workers, while working on 5-chloro-4,6-dinitrobenzofuroxan, had an intuition that 7-amino-4,6-dinitrobenzofuroxan (ADNBF) [Structure (2.48)] may be an IHE which proved to be correct at the end of the investigation [148, 149]. 

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C. D. Hutchinson and co-workers, "Initiation and Detonation Properties of the Insensitive High Explosive TATB/KEL-F800 95/5," Vol. 1, in... 

Study of Insensitive High Explosives and Propellants," in Proceedings of Conference USDRC E 79-653, Mar. 1979. 

R. D. Lynch and co-workers, "Characteri2ation of Insensitive High Explosives Developed with Propellant Technology," in Proc. 1990JANNAF Propulsion Meeting VIII, 3-5 CPIA Pubhcation 550, CPIA, Laurel, Md., Oct. 1990, pp. 3—5. 

Gaine. An intermediate booster charge used between a detonator and an insensitive high explosive. 

R.W. Millar, S.E. Philbin, R.P. Claridge, J. Hamid, Studies of novel heterocyclic insensitive high explosive compounds pyridines, pyrimidines, pyrazines and their bicyclic analogues . Propellants Explos. Pyrotech. 81—92. 

B. M. Dodratz, Insensitive High Explosive Triaminotrinitrobenzene (TATB) Development and Characterization - 1888 to 1994 , Los Alamos National Laboratory Report LA-i30i4-/7, (1995) University of California, Report UC-741. 

Poullain and co-workers ° synthesized Af-substituted-3,5-diamino-4-nitropyrazoles by treating substituted pyrimidines with Af-alkylhydrazines. 3,5-Diamino-4-nitropyrazole (14) has been synthesized by treating the pyrimidine (13) with hydrazine hydrate. This methodology is limited in scope but the products are useful intermediates for the synthesis of insensitive high explosives. 

W. P. Norris, 7-amino-4,6-dinitrobenzofuroxan, an Insensitive High Explosive , NWC TP 6522 (1984), Naval Weapons Center, China Lake, CA. 

C. N. Lovey, R. J. Spear and M. J. Wolfson, A Preliminary Assessment of NTO as an Insensitive High Explosive , MRL-TR-89-18, Materials Research Laboratory, Victoria, Australia. 

Hexanitrostilbene (HNS) Heat stable and relatively insensitive high explosive used in slapper detonators. 

The high stability of TATB favors its use in military and civilian applications where insensitive high explosives are required. In addition to its applications as a HE, TATB is also used to produce the important intermediate benzenehexamine which has been used in the preparation of ferromagnetic organic salts and in the synthesis of new heteropolycyclic molecule such as 1,4,5,8,9,12-hexaazatriphenyl-ene (HAT) that serves as a strong electron acceptor ligand for low-valence transition metals. 

Becuwe, A., and Delclos, A. (1989) Use of oxynitrotriazole to prepare an insensitive high explosive. Proc. 9th (Inti.) Symp. on Detonation, Office of the Chief of Naval Research, Arlington, VA, pp. 1008-1013. 

H. R., and Jones, A.G. (1989) Initiation and detonation properties of the insensitive high explosive TATB/Kel-F800 95/5. Proc. 9th Symp. (Inti.) on Detonation, Portland, Oregon, USA, p. 123. 

Nitroguanidine is also of interest as an insensitive high explosive (-> LOVA) its energy is low, but density and detonation velocity are high. 

Another very insensitive high explosive which is structurally closely related to CL-20 is 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX, see Fig. 1.7), which was first described by Ramakrishnan and his co-workers in 1990. It displays one of the highest densities of all nitramines (2.008 g cnr3) [lc]. 

Another N-oxide which has recently been suggested by Chavez et al. (LANL) as an insensitive high explosive is 3,3 diaminoazoxy furazan (DAAF). Though the detonation velocity and detonation pressure of DAAF are rather low (7930 m s 1, 306 kbar 1.685 g/cc), the low sensitivity (IS > 320 cm, FS > 360 N) and a critical diameter of < 3 mm make this compound promising. The synthesis of DAAF is shown in Fig 1.13b. 

The sensitivity and performance values (Tab. 9.10) revealed that ADNQ may be a high-performing but still relatively insensitive high explosive, while APX needs to be classified as a primary explosive due to its high impact sensitivity. 

Going from one of the most sensitive of the aromatic explosives to one of the very least sensitive, we have TATB (Figure 3.18). This is a new, very insensitive, high explosive that is finding broad use in nuclear weapons development. The extreme degree of insensitiveness boosts the safety in handling and in accident situations, which is so crucial in that particular application. It is made by direct nitration of 1,3,5-trichlorobenzene to 1,3,5-trichloro-2,4,6-trinitrobenzene. This, in turn, is then converted to the 1,3,5-triamino- by amine substitution of the three chlorine atoms. 

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