Furazans with Azo Linkages: Stable CHNO Energetic Materials with High Densities, Highly Energetic Performance, and Low Impact and Friction Sensitivities

Abstract

Various highly energetic azofurazan derivatives were synthesized by simple and efficient chemical routes. These nitrogen-rich materials were fully characterized by FTIR spectroscopy, elemental analysis, multinuclear NMR spectroscopy, and high-resolution mass spectrometry. Four of them were further confirmed structurally by single-crystal X-ray diffraction. These compounds exhibit high densities, ranging from 1.62 g cm(-3) up to a remarkably high 2.12 g cm(-3) for nitramine-substituted azofurazan DDAzF (2), which is the highest yet reported for an azofurazan-based CHNO energetic compound and is a consequence of the formation of strong intermolecular hydrogen-bonding networks. From the heats of formation, calculated with Gaussian 09, and the experimentally determined densities, the energetic performances (detonation pressure and velocities) of the materials were ascertained with EXPLO5 v6.02. The results suggest that azofurazan derivatives exhibit excellent detonation properties (detonation pressures of 21.8-46.1 GPa and detonation velocities of 6602-10 114 m s(-1) ) and relatively low impact and friction sensitivities (6.0-80 J and 80-360 N, respectively). In particular, they have low electrostatic spark sensitivities (0.13-1.05 J). These properties, together with their high nitrogen contents, make them potential candidates as mechanically insensitive energetic materials with high-explosive performance.

Synthesis of 1,2,3,4‐Tetrazine 1,3‐Dioxides Annulated with 1,3 a,4,6 a‐Tetraazapentalene Systems

“…Such conformation is stabilized both by conjugation and intramolecular N−H…N hydrogen bond (N(8)…N(2) 2.731(1) Å, H…N 2.07(2) Å and N−H−N 131°). The bond lengths in 15 are close to the expected ones . In crystal molecules are assembled into dimers by stacking interaction of phenyl rings [N(8) atom is located below the center of the neighboring ring] with the shortest C(1′)…C(1′) contact equal to 3.309 Å.…”

Review on the Synthesis and Performance for 1,3,4‐Oxadiazole‐Based Energetic Materials

“…Compound 49 ( (83 %). Moreover, the oxidative coupling of 38 by KMnO 4 in HCl provided the corresponding azo compound 52 with an azo group linked to 1,2,5-oxadiazole but not to 1,3,4-oxadiazole [68].…”

1,2,5‐Oxadiazole‐Based High‐Energy‐Density Materials: Synthesis and Performance

“…Synthesized azofurazans exhibit good thermal stabilities (T d >230 °C) and, with an exception of compound 77 b , high enthalpies of formation. Furthermore, dinitramine 79 has excellent detonation performance ( D =10111 m s −1 , P =46.1 GPa) which exceeds that of RDX ( D =8977 m s −1 , P =35.1 GPa) and HMX ( D =9221 m s −1 , P =39.2 GPa) . However, its higher sensitivity and possible corrosivity due to the presence of highly acidic nitramine moieties restrict potential applications of this HEDM.…”

“…3‐Amino‐4‐amidoximinofurazan 2 i was served as an initial compound for the synthesis of a series of other energetic structures comprising of furazan and 1,2,4‐ or 1,3,4‐oxadiazole rings. In particular, several 3‐amino‐4‐(1,2,4‐oxadiazol‐3‐yl)furazans 75 a‐c and 3‐amino‐4‐(1,3,4‐oxadiazol‐3‐yl)furazans 76 were synthesized . Oxidative coupling of aminofurazans 71 , 75 a – c by KMnO 4 in HCl provided corresponding azo compounds 77 a – d and 78 .…”