Sila-explosives offer a better bang

By swapping a silicon atom for a carbon atom in a pair of common high explosives, a German research team has devised a new class of compounds with the potential to outperform traditional organic nitrogen explosives and have a lower environmental impact (J. Am. Chem. Soc., DOI: 10.1021/ja071299p). The work led by Thomas M. Klapötke of Ludwig Maximilians University, in Munich, and Reinhold Tacke of the University of Würzburg appears to be the first systematic study of silicon-based high explosives, the researchers say. The team synthesized Si(CH₂ONO₂)₄ and Si(CH₂N₃)₄, which are analogs of pentaerythritol tetranitrate (PETN) and pentaerythrityl tetraazide, respectively. The "unexpected extreme sensitivity" of the silicon compounds limited the ability of the researchers to fully characterize them, Klapötke tells C&EN, and they "are far too shock-sensitive for any practical application." But work to prepare more stable versions of the sila-explosives is under way. The new explosives are expected to reduce or preclude formation of toxic organic nitrogen by-products.