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4 catalysts
Published in Binoy K. Saikia, Advances in Applied Chemistry and Industrial Catalysis, 2022
Wei Liu, Kun Chen, Zhengzheng Zhang, Huanming Liu, Na Li, Shaohua Jin, Siwei Zhao
2, 4, 6, 8, 10, 12-Hexanitro-2, 4, 6, 8, 10, 12-hexaazaiso wurtzitane (HNIW or CL-20) is the highest-energy explosive that is currently produced and applied in engineering applications, and its synthesis has always been the focus of attention by scientists from all over the world. Although many synthetic methods of CL-20 had been found, the most concise and economical synthesis route is still the routes: (1) the synthesis of 2, 4, 6, 8, 10, 12-hexabenzyl-2, 4, 6, 8, 10, 12-hexaazaiso wurtzitane (HBIW) by condensation of glyoxal and benzamide, (2) HBIW undergoes hydrogenolysis and nitration to synthesize CL-20 (Koskin 2017; Simakova 2012). These routes remove the benzyl group by hydrogenolysis, which uses H2 as a reducing agent and can reduce the cost of this route. However, precious metals of Pd are necessary as a catalyst for the hydrogenolysis of HBIW. At the same time, the catalyst cannot be reused resulting in an increase in the production cost of CL-20 and limiting its application. Therefore, the catalysts for the use of hydrogenolysis of HBIW have always been a research hotspot.
Synthetic Methods for High-Energy Organofluorine Compounds
Published in Mark J. Mezger, Kay J. Tindle, Michelle Pantoya, Lori J. Groven, Dilhan M. Kalyon, Energetic Materials, 2017
Chapman synthesized HNFX in a multistep process starting from the readily available p-nitrobenzenesulfonamide and epichlorohydrin.12–16 HNFX has a density of 1.807 g cm−3, as compared to a density of 1.65 g cm−3 for TNT, and therefore is expected to be superior to TNT as a high-energy material. Although molecular dynamic-based computations have suggested that for HNFX, although multiple polymorphs with various densities are possible, multiple recrystallization attempts yielded only one type of polymorph, that is, the low-density Ci R-3 polymorph, thus limiting the application areas for HNFX.21 This is unlike other energetic materials such as CL-20 (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane), which exhibits multiple polymorphs.21 For comparison, the densities of the well-known high-energetic materials RDX (1,3,5-trinitroperhydro-1,3,5-triazine), HMX, CL-20, and TNT are 1.81, 1.91, 2.04, and 1.65 g cm−3, respectively. On the other hand, the densities of the nonenergetic compounds such as trifluorotoluene (d = 1.19 g cm−3) are much lower. The higher densities translate into the higher detonation pressures and detonation speeds for the energetic materials. A single-crystal X-ray diffraction of the HNFX shows channel-like cavities in its unit cell.12
Formation of Nanosized Aluminum and Its Applications in Condensed Phase Reactions
Published in Claudia Altavilla, Enrico Ciliberto, Inorganic Nanoparticles: Synthesis, Applications, and Perspectives, 2017
Jan A. Puszynski, Lori J. Groven
During the past decade, a significant research effort has been made to understand the reactivity of elemental nanopowders, such as aluminum, boron, silicon, and several transition metals with different oxidizers. The research effort has also been on investigation of these fuel particles as an energetic enhancement of secondary energetic systems. Energetic materials are a subclass of reactive materials containing both fuel and oxidizer. These materials can be further classified as homogeneous or heterogeneous systems, depending on whether the oxidizer is chemically or physically linked to the fuel. These types of energetic materials are commonly used as propellants, explosives, or pyrotechnics. Homogeneous energetic materials are based on monomolecular compounds, such as TNT, RDX, HMX, and CL-20 (Dreizin 2009). The maximum energy released by these compounds during the combustion process is 50%–500% lower than the energy generated by the combustion of elemental reactants. For example, the oxidation of aluminum or boron generates approximately 30 kJ/g or 58 kJ/g, respectively, compared to 10 kJ/g for HMX energetic material. In order to take advantage of the large energy associated with the oxidation of elemental powders in energetic systems, it is necessary to increase the combustion front velocity by two to three orders of magnitude. Traditionally used micron-sized powders in thermite mixtures are characterized by very low combustion front velocities, only a few meters per second. Therefore, efforts to reduce the average particle size of a fuel reactant are necessary to obtain much faster reaction rates.
An overview over dinitramide anion and compounds based on it
Published in Indian Chemical Engineer, 2020
HNIW ([C6H6N6(NO2)6], hexanitro hexaazaisowurtzitane) or CL-20 is the highest energy compound known till date and is a member of nitroamine family. It also possesses the highest density of any known organic compound. CL-20 is a white powder with onset decomposition temperature of 215°C. It is also compatible with most of the oxidisers and binders, such as research development explosive, high melting explosive, ammonium perchlorate (AP), isocyanates, glycidylazide polymer and hydroxyl terminated poly butadiene (HTPB) [5]. Thus, CL-20 as an oxidiser when formulated with available energetic binders than it can outperform the conventional AP/HTPB-based solid propellants in respect of high specific impulse, minimum smoke and improved ballistic range.
Right on target: using plants and microbes to remediate explosives
Published in International Journal of Phytoremediation, 2019
Elizabeth L. Rylott, Neil C. Bruce
A comparatively recent addition to the nitramine class, is the cyclic nitroamine compound 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20; China Lake compound #20). This compound is being tested as a propellant because it has higher energy per mass and energy density levels than the currently used HMX. Also, unlike the bright flame and dense smoke trails produced by aluminium-based propellants, CL-20-based propellants are described as smokeless. Testing from 2000 to 2010 (reviewed by Crocker et al. 2006; Rylott and Bruce 2009; Rylott, Lorenz, et al. 2011) found acute and chronic toxicities for CL-20 in both invertebrates and vertebrates, with CL-20 now described as a neurotoxin (Gong et al. 2012). In plants and microorganisms, CL-20 causes little toxicity, and although biodegradation rates in the soil are low, mineralization by fungi and bacteria has been demonstrated. Costs remain prohibitively high for wide-scale production of CL-20 (Chaturvedi and Dave 2015), and there has been little scientific research in this area in recent years.
Combustion of Composite Propargyl-Terminated Copolyether Propellant Containing Ammonium Dinitramide
Published in Combustion Science and Technology, 2020
Li Gong, Xuyuan Zhou, Yanpei Guo, Yuping Li, Jianmin Li, Rongjie Yang
Ammonium perchlorate (AP) is a classical oxidizer in composite propellants. However, the combustion of AP could produce hydrogen chloride (HCl). ADN could become the alternative for AP as its molecular structure is endowed with high nitrogen, high oxygen and halogen-free contents (Lempert et al., 2009). CL20 is one of the best high energetic density compounds and benefits the total energy release of propellants by substituting hexahydro-1,3,5-trinitro-s-triazine (RDX) (Nielsen et al., 1998).