合成黑索今中副产物3,5-二硝基-1-氧-3,5-二氮杂环己烷的晶体结构及热分解动力学（英文）

Crystal Structure and Thermal Decomposition Kinetics of Byproduct of Synthesis of RDX: 3,5-Dinitro-1-oxygen-3,5-diazacyclohexane

直接法硝解乌洛托品制备黑索今的过程中合成了一种新型的环形副产物,采用硅胶柱层析法分离得到3,5-二硝基-1-氧-3,5-二氮杂环己烷,洗脱剂为:丙酮/二氯甲烷,梯度洗脱.以丙酮为溶剂培养得到了3,5-二硝基-1-氧-3,5-二氮杂环己烷单晶,用元素分析、傅里叶变换红外(FTIR)光谱、核磁共振氢谱(NMR)以及质谱(MS)对其结构进行了表征,用X射线单晶衍射仪测定了其晶体结构.结果表明,晶体C3H6N4O5分子量为178.12,属于单斜晶系,空间群P121/n1,晶胞参数:a=0.58128(13)nm,b=1.72389(14)nm,c=0.71072(6)nm,β=112.056°,V=0.66006(16)nm3,Z=4,DC=1.792 g cm–3,μ=0.17 mm–1,F(000)=368.0,最终偏差因子R=0.0397.用同步热分析仪技术研究了3,5-二硝基-1-氧-3,5-二氮杂环己烷的热行为,DSC曲线上在383.15和519.05 K分别有一个尖锐的熔化吸热峰和分解放热峰.另外,根据Kissinger方程及Flynn-Wall-Ozawa方程和不同升温速率下的TG曲线计算得到了该化合物的热分解动力学参数(活化能和指前因子),利用Coats-Redfern法研究了该物质的热分解机理.结果表明:3,5-二硝基-1-氧-3,5-二氮杂环己烷是一种低熔点、热稳定性好的化合物.Kissinger方程计算其活化能为212.32 k J mol–1,指前因子为6.20×1020 s–1,Flynn-Wall-Ozawa方程计算其活化能为210.39 k J mol–1,该物质的热分解动力学方程为G(α)=(1–α)–1–1,反应级数为2.

A new cyclic byproduct was formed during hexahydro-1,3,5-trinitro-1,3,5-triazine（RDX）preparation by direct nitration. Silicone column chromatography with acetone and dichloromethane in various ratios as the eluent was used to separate 3,5-dinitro-1-oxygen-3,5-diazacyclohexane from the product mixture. A single crystal of 3,5-dinitro-1-oxygen-3,5-diazacyclohexane was grown from acetone,and characterized using elemental analysis, Fourier-transform infrared（FTIR） spectroscopy, 1H nuclear magnetic resonance（NMR） spectroscopy, and mass spectrometry（MS）. Its structure was determined using an X-ray single-crystal diffractometer. The results indicate that the crystal molecular weight is178.12. It belongs to the monoclinic system with the space group P121/n1, a = 0.58128（13） nm, b =1.72389（14） nm, c = 0.71072（6） nm, β = 112.056°, V = 0.66006（16） nm3, Z = 4, DC = 1.792 g cm–3, μ =0.17 mm–1, and F（000） = 368.0; the final deviation factor R is 0.0397. Differential scanning calorimetrythermogravimetry（DSC-TG） was used to investigate the thermal behavior of the title compound. Sharp peaks were observed at 383.15 K（melting） and 519.05 K（decomposition）. The kinetic parameters were obtained using the Kissinger and Flynn-Wall-Ozawa methods and the TG data at different heating rates.The Coats-Redfern method was used to study the thermal decomposition mechanism of 3,5-dinitro-1-oxygen-3,5-diazacyclohexane. The results show that the title compound is a low-melting-point compound with good stability; its apparent activation energy and pre-exponential factor, calculated using the Kissinger equation, are 212.32 k J mol–1 and 6.20 × 1020 s–1, respectively. The apparent activation energy, calculated using the Flynn-Wall-Ozawa equation, is 210.39 k J mol–1. G（α） =（1 – α）–1 – 1（n = 2） obtained using CoatsRedfern method is regarded as the most appropriate thermal decomposition kinetic equation.