- Nonmetallic Pentazole Salts Based on Furazan or 4-Nitropyrazole for Enhancing Density and Stability
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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.
- Chen, Jieyi,Cheng, Guangbin,Hu, Bingcheng,Hu, Wei,Sun, Chengguo,Yang, Hongwei,Zhang, Chong
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p. 2690 - 2698
(2021/05/10)
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- An efficient strontium-based combustion inhibitor of ammonium perchlorate with a 2D-MOF structure
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In this study, a new strontium 2D-MOF, {[Sr(AFCA)2(H2O)2]·2H2O}n(AFCA = 4-aminofurazan-3-carboxylic acid), was successfully prepared by slow evaporation at room temperature. Its structure was characterized by X-ray single-crystal diffractometry. DTA as an efficient thermal analysis method was used in this study to have a better understanding of the thermal decomposition of ammonium perchlorate (AP). The Kissinger and the Ozawa-Doyle methods were also applied to determine the apparent activation energy (E) and the pre-exponential factor (A) of AP thermal decomposition. After the addition of {[Sr(AFCA)2(H2O)2]·2H2O}nin AP, there is an increase of 85.97 °C in the LTD stage of AP thermal decomposition and an insignificant decrease of 24.32 °C in the HTD stage. With the help of the TG-DSC-DTG method, we analyse the catalytic mechanism of AP in the LTD stage in detail. {[Sr(AFCA)2(H2O)2]·2H2O}ncan act as an efficient combustion inhibitor for AP thermal decomposition.
- Huang, Yao,Peng, Rufang,Jin, Bo
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p. 11068 - 11074
(2021/07/06)
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- 1,3,4-Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level
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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.
- Ma, Jinchao,Chinnam, Ajay Kumar,Cheng, Guangbin,Yang, Hongwei,Zhang, Jiaheng,Shreeve, Jean'ne M.
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p. 5497 - 5504
(2021/01/26)
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- A Safer Synthesis of the Explosive Precursors 4-Aminofurazan-3-Carboxylic Acid and its Ethyl Ester Derivative
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A safe and efficient one-pot synthesis of 4-aminofurazan-3-carboxylic acid and its hydrogen chloride gas-free conversion to the ethyl ester derivative are described. Previous syntheses of these intermediates were plagued with mischaracterization issues, low yields, and/or dangerous exothermic profiles. The safe scale-up of these materials not only provides benefits to the energetic materials community but may also be of importance to the pharmaceutical and agrochemicals industries.
- Johnson, Eric C.,Miller, Christopher W.,Orlicki, Joshua A.,Sabatini, Jesse J.,Sausa, Rosario C.
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p. 599 - 603
(2020/04/20)
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- Azo1,3,4-oxadiazole as a Novel Building Block to Design High-Performance Energetic Materials
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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.
- Wang, Qian,Shao, Yanli,Lu, Ming
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p. 839 - 844
(2019/01/25)
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- Energetic furazan-triazoles with high thermal stability and low sensitivity: Facile synthesis, crystal structures and energetic properties
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Crystal stacking has significant implications for the properties of energetic materials, especially molecular stability. A series of furazan-triazole energetic compounds with diverse crystal stacking forms were synthesized through a facile procedure. All new compounds were characterized by NMR spectroscopy, IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Single crystal X-ray diffraction analysis indicated that compounds 2a and 2c show face-to-face stacking, while compounds 3 and 3a exhibit wave-like stacking as a result of their planar furazan-triazole skeleton. Furthermore, on the basis of single-crystal data, noncovalent interactions were analyzed to comprehensively study their structure-property relationships. Compound 2b is highly stable, exhibiting a decomposition temperature of 324 °C, an impact sensitivity of >40 J, and a friction sensitivity of >360 J, thereby demonstrating its potential application as a heat-resistant and insensitive explosive. Meanwhile, 3b with its superior detonation velocity (9114 m s-1) and pressure (35.8 GPa) and favorable stability (Td = 226 °C, IS = 20 J, FS = 280 N), exhibits a performance superior to that of RDX. This work provides insights into the combination of molecular design and crystal stacking for generating new energetic materials.
- Liu, Yang,Xu, Yuangang,Sun, Qi,Lu, Ming
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p. 6093 - 6099
(2019/10/22)
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- NOVEL FURAZAN-3-CARBOXYLIC ACID DERIVATIVES AND USE THEREOF IN TREATMENT OF CANCER
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A furazan-3-carboxylic acid derivative or pharmaceutically acceptable salt thereof for use in treatment of acute myeloid leukemia.
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Paragraph 0092; 0093
(2018/04/19)
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- Crystal structures of the "two" 4-aminofurazan-3-carboxylic acids
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The crystal structures of the two compounds reported to be 4-aminofurazan-3-carboxylic acid have been determined. The compound reported by Sheremetev et al. (J Heterocycl Chem 2005, 42, 519) is the actual 4-aminofurazan-3-carboxylic acid. The compound reported by Meyer (Org Prep Proced Int 2004, 36, 361) is the interesting complex formed from a molecule of the acid and a molecule of the potassium salt of the acid..
- Willer, Rodney L.,Storey, Robson F.,Frisch, Mark,Deschamps, Jeffery R.
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experimental part
p. 227 - 231
(2012/05/05)
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- Synthesis and X-ray study of novel azofurazan-annulated macrocyclic lactams
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Reaction of 1,4-di-(3-aminofurazan-4-oyl)piperazine 4 with dibromoisocyanurate (DBI) affords azofurazan-annulated macrocyclic lactam 7; the X-ray structure of the macrocycle 7 is reported. The synthesis was started with 3-aminofurazan-4-carboxylic acid 1. A one-pot method for preparation of the amino acid was elaborated from commercially available cyanoacetic ester. Amides of the acid have been prepared via the esterification and subsequent amination.
- Sheremetev, Aleksei B.,Aleksandrova, Nataliya S.,Dmitriev, Dmitrii E.,Averkiev, Boris B.,Antipin, Mikhail Yu.
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p. 519 - 525
(2007/10/03)
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- AMINO-GROUP EXCHANGE AND RING-CLEAVAGE REACTIONS IN FUSED 1,2,6-THIADIAZIDINE DIOXIDE DERIVATIVES
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Reactions of 7-amino-4H-furazanothiadiazine 5,5-dioxide (1) and its 4-methyl derivative (2) with nucleophilic agents under different conditions, are described.Besides the products resulting from the displacement of the 7-amino group, those p
- Fernandez-Resa, Piedad,Goya, Pilar,Nieves, Rosa,Ochoa, Carmen,Stud, Manfred
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p. 2351 - 2353
(2007/10/02)
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