Zhu Shuangfei, Yang Wei, Gan Qiang, Cheng Nianshou, Feng Changgen
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.
Phys Chem Chem Phys. 2022 Jan 19;24(3):1520-1531. doi: 10.1039/d1cp02881b.
Exploration of the initial reactions of H-free and nitro-free energetic materials could enrich our understanding of the thermal decomposition mechanism of various energetic materials (EMs). In this work, two furoxan compounds, 3,4-dinitrofurazanfuroxan (DNTF) and benzotrifuroxan (BTF), were investigated to shed light on the decay mechanism of furoxan compounds based on the combination of self-consistent charge density functional tight binding and molecular dynamics simulations. The results show that DNTF and BTF decay a unimolecular mechanism, and the transformation of the furoxan ring into a nitro group is suggested as a novel initial channel. Five initial steps of DNTF thermal decomposition are observed, including NO loss and the N(O)-O bond cleavage of the central and peripheral rings. The bond cleavage of peripheral rings dominates the decay at low temperatures, while the central ring opening and C-NO dissociation govern the high temperature decay. Besides, NO, CO and NO fragments are mainly yielded at high temperatures, while CON is dominant at low temperatures. The three-stage characteristic of the exothermic BTF decay is described under programmed heating conditions for the first time. Four initial steps of BTF thermal decomposition were identified, including furoxan ring opening reactions and the breakage of the 6-membered ring C-C bond. The cleavage of the N(O)-O bond is dominant in the initial step of BTF decomposition under different heating conditions, and the frequency increases with increasing temperature. In addition, the amounts of CON, ON and CO are higher at high temperatures, while CON shows an opposite trend. The findings of this work provide deep insights into the complicated sensitivity mechanism of EMs.
探索无氢和无硝基含能材料的初始反应，有助于丰富我们对各种含能材料（EMs）热分解机理的理解。在这项工作中，基于自洽电荷密度泛函紧束缚和分子动力学模拟相结合的方法，研究了两种呋咱化合物3,4-二硝基呋咱基氧化呋咱（DNTF）和苯并三呋咱（BTF），以阐明呋咱化合物的分解机理。结果表明，DNTF和BTF按单分子机理分解，呋咱环向硝基的转变被认为是一种新的初始通道。观察到DNTF热分解的五个初始步骤，包括NO损失以及中心环和外围环的N（O）-O键断裂。低温下外围环的键断裂主导分解，而高温下中心环开环和C-NO解离起主导作用。此外，NO、CO和NO片段主要在高温下产生，而CON在低温下占主导。首次在程序升温条件下描述了放热的BTF分解的三阶段特征。确定了BTF热分解的四个初始步骤，包括呋咱环开环反应和六元环C-C键的断裂。在不同加热条件下，N（O）-O键的断裂在BTF分解的初始步骤中占主导，且频率随温度升高而增加。此外，CON、ON和CO的量在高温下较高，而CON则呈现相反趋势。这项工作的发现为深入了解含能材料复杂的感度机理提供了见解。
