Synthesis and characterization of imidazo[1,2-d][1,2,4]oxadiazole-functionalized furazan energetic compounds

Two novel oxygen-containing imidazo[1,2-d][1,2,4]oxadiazole heterocycle compounds 2 and 3 were successfully synthesized by oxidation of the aminofurazan group. Compounds 2 and 3 were fully characterized by Fourier Transform Infrared, multinuclear NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Their properties were evaluated by measured density, impact, and friction sensitivities, calculated heat of formation, and detonation performances. Compound 2 has high density (1.87 g cm-3), good detonation velocity and pressure (D:8690 m s-1, P: 33.3 GPa), acceptable sensitivity (IS: 12 J, FS: 144 N), and its overall performance is comparable to RDX. Compound 3 has a better sensitivity (IS: 28 J, FS: 252 N), but the detonation performance is average (D:8008 m s-1, P: 27.4 GPa), which may be caused by its low packing index (70.9%) affecting its density (1.78 g cm-3). The oxidation of amino group in 4-(6-Nitroimidazo[1,2-d][1,2,4]oxadiazol-3-yl)-1,2,5-oxadiazol-3-amine to nitro groups or azo group was applied to enhance its energetic performances.image