78350-50-2Relevant articles and documents
Nonmetallic Pentazole Salts Based on Furazan or 4-Nitropyrazole for Enhancing Density and Stability
Chen, Jieyi,Cheng, Guangbin,Hu, Bingcheng,Hu, Wei,Sun, Chengguo,Yang, Hongwei,Zhang, Chong
, p. 2690 - 2698 (2021/05/10)
In this work, three novel nonmetallic pentazole salts (6-8) based on furazan or 4-nitropyrazole were synthesized. Some coplanar groups were introduced into the compounds to improve the planarity of the crystal packing. 4-Amino-1,2,5-oxadiazole-3-carbohydrazonamide pentazolate (6), 5-(4-amino-1,2,5-oxadiazol-3-yl)-4H-1,2,4-triazole-3,4-diamine pentazolate (7), and 5,5′-(4-nitro-1H-pyrazole-3,5-diyl)-bis(4H-1,2,4-triazole-3,4-diamine) pentazolate (8) all show more stable π-πstacking and exhibit superior thermal stability (110.5-116.4 °C) than most other reported nonmetallic pentazole salts (Tonset: 80-110 °C), and compound 8 has the highest crystal density (1.722 g·cm-3/173 K) of nonmetallic pentazole salts to date. All salts have been thoroughly characterized by NMR (1H and 13C) spectroscopy, infrared (IR), Roman (RA), and elemental analysis. The decomposition temperature of all salts displays more than 110 °C, which is measured by differential scanning calorimetry (DSC). These compounds all shows low sensitivity (IS > 35 J, FS > 360 N) measured by standard BAM methods. Glycidyl azide polymer (GAP) based propellant formula with the addition of salt 6 or 7 shows a higher specific impulse (6, Isp = 262.1 s; 7, Isp = 263.9 s) than that of RDX (Isp = 259.0 s). This study can provide a new crystal engineering way for the synthesis of pentazole salt to solve the problem of low density and poor stability.
1,3,4-Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level
Ma, Jinchao,Chinnam, Ajay Kumar,Cheng, Guangbin,Yang, Hongwei,Zhang, Jiaheng,Shreeve, Jean'ne M.
, p. 5497 - 5504 (2021/01/26)
Many energetic materials synthesized to date have limited applications because of low thermal and/or mechanical stability. This limitation can be overcome by introducing structural modifications such as a bridging group. In this study, a series of 1,3,4-oxadiazole-bridged furazans was prepared. Their structures were confirmed by 1H and 13C NMR, infrared, elemental, and X-ray crystallographic analyses. The thermal stability, friction sensitivity, impact sensitivity, detonation velocity, and detonation pressure were evaluated. The hydroxylammonium salt 8 has an excellent detonation performance (D=9101 m s?1, P=37.9 GPa) and insensitive properties (IS=17.4 J, FS=330 N), which show its great potential as a high-performance insensitive explosive. Using quantum computation and crystal structure analysis, the effect of the introduction of the 1,3,4-oxadiazole moiety on molecular reactivity and the difference between the sensitivities and thermal stabilities of mono- and bis-1,3,4-oxadiazole bridges are considered. The synthetic method for introducing 1,3,4-oxadiazole and the systematic study of 1,3,4-oxadiazole-bridged compounds provide a theoretical basis for future energetics design.
Azo1,3,4-oxadiazole as a Novel Building Block to Design High-Performance Energetic Materials
Wang, Qian,Shao, Yanli,Lu, Ming
, p. 839 - 844 (2019/01/25)
In this study, the azo1,3,4-oxadiazole energetic fragment was first introduced into the energetic materials using a simple synthetic strategy, yielding two symmetrical covalent compounds 4 and 5. All new compounds (3-5) were well-characterized by IR spectroscopy, NMR spectroscopy, thermal analysis, and single-crystal X-ray diffraction analysis. As supported by differenctial scanning calorimetry data, compounds 4 and 5 possess excellent decomposition temperatures as high as 248 and 278 °C, respectively. To the best of our knowledge, 278 °C ranks highest in all 1,3,4-oxadiazole-based energetic compounds. Their energetic performances were evaluated with EXPLO5. Both 4 and 5 show good detonation velocities (D) of 8409 and 8800 m s-1 and detonation pressures (P) of 29.3 and 35.1 GPa, comparable to RDX (D: 8795 m s-1, P: 34.9 GPa). Furthermore, on the basis of the single-crystal data, quantum-chemical calculations were employed to better understand their intrinsic structure-property relationship. All these positive results indicate the superior potential of the azo1,3,4-oxadiazole backbone for designing next generation of energetic materials.
