Combination of 1,2,4-Oxadiazolone and Pyrazole for the Generation of Energetic Materials with Relatively High Detonation Performance and Good Thermal Stability

Oxadiazoles are the satisfactory structural units of energetic materials due to high densities. However, the practical use of most oxadiazole compounds in energetic materials is limited by their low thermal decomposition temperature (<180 °C). In this work, 3-(3-nitro-1H-pyrazol-4-yl)-1,2,4-oxadiazol-5(4H)-one (6) with relatively high detonation performance (Dv = 8315 m s–1; P = 29.22 GPa) and good thermal stability (Td = 275.9 °C) has been successfully synthesized by the introduction of a pyrazole backbone into the oxadiazole skeleton, which is better than HNS (Dv = 7612 m·s –1; P = 24.3 GPa). In addition, compound 6 was synthesized using a green, low-toxicity three-step process (cyclization, amination, and hydrolysis) rather than highly toxic cyanogen bromide. To investigate the correlation between the structure and stability of compound 6, calculations of Hirshfeld surface analysis, 2D-fingerprint plots, and electrostatic potentials were performed. This provides a guide to synthesizing energetic materials with high detonation and good thermal stability.