Since the demands for the thermostability of energetic materials have risen in the deep mining and aerospace industry, the research on heat‐resistant explosives with remarkable thermal stability as well as...

No abstract

Unsymmetrical functionalization of bis-1,2,4-triazoles was attempted, and a series of nitrogen/oxygen-rich energetic materials were designed and synthesized in this study. Compared with previously reported symmetrical bis-1,2,4-triazole derivatives (iv and v), both unsymmetrically functionalized bis-1,2,4-triazole derivatives (3 and 7) in this work possess improved safety properties (impact sensitivities: 22 J (3) and 11 J (7); friction sensitivities: >360 N (3) and 250 N (7)). Meanwhile, the detonation performance of 3 was apparently improved compared with the C-nitrated compound iv. These features indicate that unsymmetrical functionalization would be a favorable strategy to construct energetic materials with both high energy and safety. Moreover, N-trinitromethyl-functionalized compound 5 possesses high density (1.92 g cm–3), positive oxygen balance (+25.1%), and desirable detonation performance similar to HMX, with higher specific impulse (I sp = 265.1 s) than ADN, suggesting its superiority as a highly energetic oxidizer.

A family of mono or di(1,2,4‐oxadiazole)‐bridged polynitropyrazole derivatives with C‐nitro/N‐nitro functionalities is reported. All compounds were fully characterized by IR, NMR (1H, 13C), elemental analysis and differential scanning calorimetry (DSC). The solid‐state structure features were further investigated with X‐ray diffraction. Of these, compounds 3,5‐bis(3,4‐dinitro‐1H‐pyrazol‐5‐yl)‐1,2,4‐oxadiazole (3 a) and 5,5′‐bis(3,4‐dinitro‐1H‐pyrazol‐5‐yl)‐3,3′‐bi(1,2,4‐oxadiazole) (3 b) possess high thermal stability (3 a: Tdec=274 °C; 3 b: Tdec=272 °C), sensitivity (IS >30 J, FS >360 N) and comparable detonation properties (3 a: Dv=8741 m s−1, P=34.0 GPa; 3 b: Dv=8685 m s−1, P=33.4 Gpa) to RDX. In addition, 3,5‐bis(4‐nitro‐1H‐pyrazol‐3‐yl)‐1,2,4‐oxadiazole (4 a) and 5,5′‐bis(4‐nitro‐1H‐pyrazol‐3‐yl)‐3,3′‐bi(1,2,4‐oxadiazole) (4 b) have high decomposition temperature (4 a: Tdec=314 °C; 4 b: Tdec=317 °C), low sensitivity (IS >40 J; FS>360 N) and superior detonation performances (4 a: Dv=8027 m s−1, P=26.4 GPa; 4 b: Dv=7991 m s−1, P=25.2 Gpa) than conventional heat‐resistant explosive hexanitrostilbene (HNS: Tdec=318 °C; IS=5 J; FS=240 N; Dv=7612 m s−1, P=24.3 GPa), thus suggesting their potential application as heat‐resistant explosives.

A combination of 1,3,4-oxadiazole and pyrazole produces a series of new compounds with satisfactory energetic properties.