Safe 'green' explosives

Environmentally friendly and safe substitutes for lead-based primaries have been developed by researchers at the University of North Carolina, Chapel Hill, and Los Alamos and Lawrence Berkeley National Laboratories. Primaries are small explosive charges used to detonate larger charges, ranging from propellants for bullets to explosives used in mining. Most are lead-based and therefore potentially harmful for the environment and for people exposed to the residue after primaries explode. These materials can also detonate accidentally. Finding a replacement has been difficult, because the substitutes also have defects, including instability or toxicity. Now, UNC chemistry professor Thomas J. Meyer and his colleagues have synthesized four green primary explosives that meet all of the criteria needed to replace those containing lead (Proc. Natl. Acad. Sci. USA 2006, 103, 5409). Based on complex metal dianions and environmentally benign cations, the compounds (one of which is shown) can be desensitized by storage in water and release no harmful residues when they blow up.