Synthesis and reactivity of 5-hydrazino-3-nitro-1,2,4-triazole (HNT): an amphoteric energetic platform

Abstract

Here is described the first synthesis of 5-hydrazino-3-nitro-1,2,4-triazole (HNT), as a free base, from 5-bromo-3-nitro-1,2,4-triazole (BNT) in three steps. HNT was found to represent a valuable platform towards powerful and thermally stable energetic compounds. Its specific amphoteric properties were demonstrated through the synthesis of both cationic and anionic salts. Densities and enthalpies of formation of compounds 3-4, 6–8 and 12–15 were measured and the respective P_CJ and D_CJ were calculated using these experimental data. Among the compounds derived from HNT, perchlorate 7 exhibits remarkable properties, with a high density of 1.95 g cm⁻³ and an outstanding detonation velocity (9505 m s⁻¹) and pressure (419 GPa), thus surpassing RDX in performance. The fused triazolo[4,3-b]triazole 4 also shows possibilities as a new potential heat-resistant explosive, due to its low sensitivity, high thermal stability (T_dec 313 °C) and overall performance data exceeding those of HNS. All compounds were fully characterized by ¹H and ¹³C NMR (¹⁵N NMR for compounds 3, 4 and 16) spectroscopy, IR spectroscopy, MS, elemental analysis and single-crystal X-ray diffraction for compound 6.