Constructing Heat-Resistant and Insensitive Energetic Compounds with the Introduction of Cyano Group into Fused Pyrazolotriazine Skeleton
Zhen Cheng, Wei Yang, Qing Ma, Zhenqi Zhang, Lei Yang, Hongwei Yang, Guijuan Fan, Guangbin Cheng
Abstract
Fused pyrazolotriazine frameworks have been used to develop novel heat-resistant energetic compounds. Diazotization of 3,4-diamino-4-nitropyrazole (1) and 3-anmio-4,5-dinitropyrazole (ADNP) followed by treatment with malononitrile afford compounds 2 and 3, including fused pyrazolotriazine ring surrounded by amino and cyano groups, respectively. Compounds 2 and 3 were thoroughly characterized by multinuclear NMR spectroscopy, infrared spectroscopy, and elemental analysis. The molecular structures of 2 and 3 were further confirmed by single crystal X-ray diffraction with the densities of 1.794 and 1.817 g·cm–3 (298 K), respectively. Moreover, compounds 2 and 3 have low impact and friction sensitivities (IS > 50 J, FS > 324 N). In particularly, compound 2 possesses the crossing stacking mode and high onset decomposition temperature of 370 °C, whose comprehensive performances are better than those of (2,2′,4,4′,6,6′-hexanitrostilbene) HNS and (2,6-bis(picrylamino)-3,5-dinitropyridine) PYX. The efficient method of malononitrile cyclization provides a new idea for the development of novel heat-resistant energetic compounds.