Pushing the limits of the heat of detonation via the construction of polynitro bipyrazole.

The trinitromethyl group is a highly oxidized group that is found as an active functionality in many high-energy-density materials. The most frequently used previous synthetic method for the introduction of the trinitromethyl group is the nitration of heterocyclic compounds containing an acetonyl/ethyl acetate/chloroxime group. Now a novel strategy for constructing a trinitromethyl group (5) via nitration of an ethylene bridged compound, dipyrazolo[1,5- a :5',1'- c ]pyrazine (2), is reported. In addition, the other two nitrated products (3 and 4) were obtained under different nitrating conditions. Compound 5 has excellent detonation performance ( D v = 9047 m s -1 , P = 35.6 GPa), and a low mechanical sensitivity ( IS = 10 J, FS = 216 N), with an especially attractive heat of detonation of 6921 kJ kg -1 , which significantly exceeds that of the state-of-the-art explosive CL-20 ( Q : 6162 kJ kg -1 ).