Fig. 1
Explosives chemist David Chavez pours an example of melt-castable explosive into a copper mold at Los Alamos National Laboratory’s Technical Area 9.

Army and DoE Researchers Develop TNT Replacement

TNT (aka trinitrotoluene) was first prepared in 1863 by German chemist Julius Wilbrand, but its full potential as an explosive wasn’t discovered until 1891. It has been in use as a munitions explosive since 1902. But the Environmental Protection Agency lists TNT as a possible carcinogen, and exposure to it has been linked to disorders of the liver and blood, according to the Centers for Disease Control. So, the Army and the Dept. of Energy have been looking for a replacement that is less toxic than TNT, packs a bigger explosive punch, and has a low melting point, which will let it be safely heated and cast in different shapes and sizes.

They recently came up with one: bis-oxadiazole, a nitrogen-containing compound. This 24-atom molecule is packed with nitrogen, and has 1.5 times the explosive power of TNT. The full chemical name is bis(1,2,4-oxadiazole)bis(methylene)dinitrate.

Oxadiazole has a calculated detonation pressure 50% higher than that of TNT. The upper image shows its molecular formation while the lower mages shows its crystal packing viewed along the b axis. Dashed blue lines represent intramolecular interactions, whereas dashed red lines represent intermolecular contacts.

The challenge then became one of getting a high enough yield of the material out of the synthesis process. An early procedure generated only a 4% yield, far too low to be practical and affordable. After several iterations of the process, scientists boosted the yield to 44%.

Research will continue into producing the material on a kilogram scale, along with more toxicity studies.

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