Synthesis of high-performance insensitive energetic materials based on nitropyrazole and 1,2,4-triazole†
A new family of symmetric (4-nitro-1H-pyrazole-3,5-diyl)bis(1H-1,2,4-triazole)-based derivatives were obtained. All these new compounds were characterized by (1H, 13C)NMR spectroscopy, infrared spectroscopy, elemental analysis and differential scanning calorimetry (DSC). The structures of 5,5′-(4-nitro-1H-pyrazole-3,5-diyl)bis(3-nitro-1H-1,2,4-triazole) (6) and N,N′-((4-nitro-1H-pyrazole-3,5-diyl)bis(1H-1,2,4-triazole-5,3-diyl))dinitramide (7) were further confirmed by single crystal X-ray diffraction. In addition, the theoretical calculations by using the Gaussian 09 package show that target compounds have high heats of formation ranging from 1.40 to 2.84 kJ g−1. Among them, the safety and detonation performances of 6 (D: 8747 m s−1, P: 33.0 GPa, Td: 238.2 °C, IS: 30 J) and energetic salts dihydroxylammonium((4-nitro-1H-pyrazole-3,5-diyl)bis(1H-1,2,4-triazole-5,3-diyl))bis(nitroamide) (9) (D: 9077 m s−1, P: 33.6 GPa, IS: >40 J) and dihydrazinium((4-nitro-1H-pyrazole-3,5-diyl)bis(1H-1,2,4-triazole-5,3-diyl))bis(nitroamide) (10) (D: 8759 m s−1, P: 30.2 GPa, IS: >40 J) are comparable to those of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX: D = 8795 m s−1, P = 34.9 GPa, Td = 210 °C, IS: 7.4 J) due to the positive effect of ternary hydrogen bonds.