November 3, 2011 | Latest News

High-Energy Salts Exhibit Explosive Potential

Energetic Materials: A new family of triazole salts combines a big bang with less of a hair trigger
Department: Science & Technology
Keywords: high-energy-density materials, explosives, energetic materials, impact sensitivity
Explosive Chemistry
New explosive triazole salts made from 5-nitro-3-trinitromethyl-1H-1,2,4-triazole (top) and 5,5’-bis(trinitromethyl)-3,3’-azo-1H-1,2,4-triazole (bottom) are more stable than other energy-rich materials.
Credit: J. Am. Chem. Soc.

When designing new explosive materials, chemists face a major hurdle: Many desirable characteristics come at the expense of others. For example, compounds that pack a large amount of energy into their bonds—and therefore produce a bigger bang—are also more likely to detonate unintentionally. Researchers may have found a happy medium with a new family of energetic triazole salts (J. Am. Chem. Soc., DOI: 10.1021/ja208990z).

The new nitro-substituted triazole salts have explosive properties similar to those of traditional explosives, but they are less impact-sensitive, a measure of an explosive’s stability, says Jean’ne Shreeve, from the University of Idaho, Moscow.

Her team looked to triazoles, because they fall between tetrazoles, which have high energy density but low stability, and imidazoles, which are more stable but less energetic.

The chemists generated a library of ten salts by reacting two acidic triazole molecules they had previously designed (J. Am. Chem. Soc., DOI: 10.1021/ja2013455) with several basic compounds. They then measured each salt’s density and calculated its heat of formation, two properties that together describe the amount of energy contained in an explosive material. The scientists also determined each salt’s impact sensitivity by dropping a weight onto about 40 mg of the compound to find the lowest force necessary to cause a flame or explosion.

The researchers found that several of the high-energy salts were less impact-sensitive than traditional explosives. For example, one of the salts formed from 5,5’-bis(trinitromethyl)-3,3’-azo-1H-1,2,4-triazole has comparable energy density to research department explosive (RDX), a commonly used explosive, but requires about twice as much force to detonate as RDX does.

Shreeve hopes that other researcher will investigate the compounds’ potential for real-life applications.

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