An unexpected method to synthesise 1,2,4-oxadiazolone derivatives: a class of insensitive energetic materials

Abstract

A new and effective method for the preparation of 3-(4-amino-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol-5(4H)-one is presented. In order to develop high energy density materials, compounds 3, 4 and 6 were synthesized by the simple nitration, oxidation and oxidation coupling reaction of compound 2. In addition, six energetic salts based on 3 and 4 were synthesized, respectively. Compounds 2–12 were characterized by IR spectroscopy, multinuclear NMR spectroscopy and elemental analysis. The structures of compounds 2, 4 and 7 were determined by single crystal X-ray diffraction. In addition, the energetic properties of compounds 3–12 including density (1.60–1.88 g cm⁻³), thermal stability (161.83–315.75 °C), except compound 3 which decomposed at 127.25 °C, and sensitivity were also investigated. The energetic performance (P: 22.25–35.81 GPa; D: 7749–8892 m s⁻¹) from the experimental densities and calculated heats of formation suggests that many of them have potential applications as energetic materials.