Nitropyrazole energetic compounds functionalized with dinitroethyl, trinitromethyl, or oxadiazolyl group: Synthesis, structure and energetic performance

Pyrazole derivatives with polynitro groups were extensively researched in energetic material field as they show high energy density and excellent detonation properties, but the specific synthesis process still encounters challenges. In this paper, we firstly combined trinitromethyl, dinitroethyl, oxadiazolyl moieties with pyrazole, successfully designed and synthesized three novel poly-nitro pyrazole energetic compounds by nitration. Their structural features were investigated using single-crystal X-ray diffraction, nuclear magnetic resonance, infrared spectroscopy. 3-(3,5-Dinitro-1 H -pyrazol-4-yl)-1,2,4-oxadiazol-5(4 H )-one ( 12 ) possessed a superior thermal stability (235.1 °C) due to the presence of strong conjugated interaction in this structure. Among all, 3-nitro-1-(trinitromethyl)-1 H -pyrazole-5-carboxylic acid ( 8 ) exhibited a good thermal stability (163.7 °C), a high density of 1.829 g cm −3 at 298 K in combination with excellent detonation properties ( D : 8747 m s −1 ; P : 33.613 GPa). The results indicate that three compounds have promise to act as novel energetic materials and the synthesis provides a direction for polynitro compounds and oxadiazol based energetic compounds.