School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China.
Xi'an Modern Chemistry Research Institute, Xi'an 710065, China.
Molecules. 2021 Nov 19;26(22):7004. doi: 10.3390/molecules26227004.
Dinitropyrazole is an important structure for the design and synthesis of energetic materials. In this work, we reported the first comparative thermal studies of two representative dinitropyrazole-based energetic materials, 4-amino-3,5-dinitropyrazole (LLM-116) and its novel trimer derivative (LLM-226). Both the experimental and theoretical results proved the active aromatic N-H moiety would cause incredible variations in the physicochemical characteristics of the obtained energetic materials. Thermal behaviors and kinetic studies of the two related dinitropyrazole-based energetic structures showed that impressive thermal stabilization could be achieved after the trimerization, but also would result in a less concentrated heat-release process. Detailed analysis of condensed-phase systems and the gaseous products during the thermal decomposition processes, and simulation studies based on ReaxFF force field, indicated that the ring opening of LLM-116 was triggered by hydrogen transfer of the active aromatic N-H moiety. In contrast, the initial decomposition of LLM-226 was caused by the rupture of carbon-nitrogen bonds at the diazo moiety.
二硝戊吡嗪是设计和合成含能材料的重要结构。在这项工作中，我们报告了两种有代表性的基于二硝戊吡嗪的含能材料，4-氨基-3,5-二硝戊吡嗪（LLM-116）及其新型三聚体衍生物（LLM-226）的首次比较热研究。实验和理论结果都证明了活性芳香族 N-H 部分会导致所得到的含能材料的物理化学性质发生惊人的变化。两种相关的二硝戊吡嗪基含能结构的热行为和动力学研究表明，三聚化后可以实现令人印象深刻的热稳定，但也会导致热量释放过程不那么集中。对热分解过程中凝聚相体系和气态产物的详细分析，以及基于 ReaxFF 力场的模拟研究表明，LLM-116 的环开反应是由活性芳香族 N-H 部分的氢转移引发的。相比之下，LLM-226 的初始分解是由重氮部分的碳-氮键断裂引起的。
