An advanced zwitterionic compound based on dinitropyrazole and 1,3,4-oxadiazole: Combining the high detonation performances and low sensitivities

Abstract

The development of energetic materials with high detonation performances and low sensitivities is a continuous pursuit for researchers. Here, the zwitterionic compound 2 (4-(2-amino-1,3,4-oxadiazol-3-ium-5-yl)-3,5-dinitropyrazol-1-ide) was synthesized, which combined high density with low sensitivity. Compared with its isomer 5-(3,4-dinitro-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-amine (iso-2), the overall properties of 2 are obviously improved. Significantly, the highly increased crystal density of 2 (2: 1.957 g cm−3 at 193 K; iso-2: 1.719 g cm−3 at 170 K) reveals that zwitterionic compound has a more compact packing model, which positively impacts the detonation properties (2: Dv = 9003 m s−1, P = 36.7 GPa; iso-2: Dv = 8035 m s−1, P = 26.9 GPa). Moreover, the thermostability of 2 (Td = 272 °C) is better than that of iso-2 (Td = 240 °C). Particularly, the mechanical sensitivities of 2 (IS = 40 J, FS = 360 N) are apparently superior to that of traditional high-performance energetic material HMX (IS = 7 J, FS = 120 N), while the detonation performances of 2 still maintain a high level close to HMX (Dv = 9144 m s−1, P = 39.2 GPa). Moreover, the nitroamino compound 3 and azo compound 4 were further developed to improve the detonation properties of 2. Unusually, the detonation properties of 3 (Dv = 8895 m s−1, P = 34.9 GPa) and 4 (Dv = 8887 m s−1, P = 34.8 GPa) were not getting better compared with 2 probably due to their lower densities. Therefore, the advantages of zwitterionic structure can be highlighted. Overall, the synthesis of zwitterionic energetic compounds have broad application prospects in the development of high-performance compounds with low sensitivities.