Constructing a framework with 1,3,4-oxadiazole and pyrazole for new high energy insensitive salts

Abstract

A novel neutral tricyclic energetic compound 5,5’ -(4-nitro-1H-pyrazole-3,5-diyl) bis (1,3,4-oxadiazol -2-amine) and a series of corresponding energetic ionic salts 7–9 were synthesized. Differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), elemental analysis, and infrared spectroscopy (IR) were used to analyze the newly synthesized compounds. Single-crystal X-ray diffraction was also used to validate the precise structure of ammonium salt 7. These energetic salts exhibit positive heat of formation (401.17 ​kJ·mol⁻¹ to 690.66 ​kJ·mol⁻¹), moderate detonation performance (8517 ​m·s⁻¹ to 8803 ​m·s⁻¹) and low mechanical sensitivity (IS ​> ​40 ​J; FS ​> ​360 ​N). It is worth noting that, in comparison to previously reported energetic salts containing nitramino 1,3,4-oxadiazole with poor thermal stability, the beginning decomposition temperatures of hydroxylamine salt 9 is greater than 180 ​°C. The newly synthesized hydroxylamine salt 9 has promise to be used as new high energy insensitive material based on the aforementioned characteristics.