Synthesis of Advanced Pyrazole and N-N-Bridged Bistriazole-Based Secondary High-Energy Materials.

In this work, we have synthesized 3,5-dihydrazinyl-4-nitro-1-pyrazole (), 9-nitro-1-pyrazolo[3,2-:5,1-']bis([1,2,4]triazole)-3,6-diamine (), and N-N-bonded ,'-{[4,4'-bi(1,2,4-triazole)]-3,3'-diyl}dinitramide () and its stable nitrogen-rich energetic salts in one and two steps in quantitative yields from commercially available inexpensive starting material 4,6-dichloro-5-nitropyrimidine (). Along with characterization via nuclear magnetic resonance, infrared, differential scanning calorimetry, and elemental analysis, the structures of and were confirmed by single-crystal X-ray diffraction. Interestingly, show excellent thermal stability (242, 221, 250, and 242 °C, respectively) compared to that of RDX (210 °C). Detonation velocities of , , , and range from 8992 to 9069 m s, which are better than that of RDX (8878 m s) and close to that of HMX (9221 m s). All of these compounds are insensitive to impact (10-35 J) and friction (360 N) sensitivity. These excellent energetic performances, stabilities, and synthetic feasibilities make compounds , , , and promising candidates as secondary explosives and potential replacements for the presently used benchmark explosives RDX and HMX.