Synthesis and Properties of 1,2,4-Triazol-3-one-Based Energetic Compounds

1,2,4-Triazol-3-one (TO) is an important nitrogen-rich heterocycle in synthesis chemistry. In the field of energetic materials, some synthesis strategies are applied to prepare TO-derived energetic materials. However, none of them can be used as a heat-resistant energetic material due to their lower decomposition temperatures. In this paper, a series of energetic TO derivatives 4–13 were prepared from 5-oxo-4,5-dihydro-1H-1,2,4-triazole-3-carboxylic acid. These compounds were fully characterized by using elemental analysis, 1H and 13C NMR spectroscopy, IR analysis, and MS. The crystal structures of fused-ring compound 6 and perchlorate 8 were further identified using single-crystal X-ray diffraction. Most compounds exhibit good thermostability (Td = 166.5–324.5 °C), low sensitivities (impact sensitivity IS ≥ 20 J; friction sensitivity FS ≥ 360 N), good detonation performance (Dv = 7905–8753 m s–1), and positive heats of formation (ΔHf = 295.9–1121.1 kJ mol–1), except compound 9 (Td = 92 °C; IS = 15 J; FS = 240 N). Among these target molecules, compound 6 with a high decomposition temperature (Td = 324.5 °C), a high density (ρ = 1.859 g cm–3), low sensitivities (IS > 40 J; FS > 360 N), and a decent detonation performance (Dv = 8406 m s–1; P = 29.2 GPa) is superior to the traditional heat-resistant explosive hexanitrostilbene (Td = 318 °C; ρ = 1.750 g cm–3; IS = 5 J; FS = 240 N; Dv = 7612 m s–1; P = 26.3 GPa) and can be used as an insensitive and thermostable energetic material.