摘要
为了合成平面型的高能钝感富氮类含能化合物,以6‑(3,5‑二甲基吡唑)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪(1)为底物,与2,6‑二氨基‑3,5‑二硝基吡嗪(2)在碱性条件下反应,合成了—NH—桥联的基于稠杂环体系的6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑1,2,4‑三唑[4,3‑b][1,2,4,5]四嗪(3),收率为81.3%。采用核磁、红外、X射线衍射等分析手段对化合物3的结构进行表征;利用差示扫描量热(DSC)研究了化合物3的热分解过程,其初始分解温度高达254.6 ℃;采用Gaussian 09 D.01和Explo5 V6.05.02软件计算化合物3的爆速和爆压分别为7568 m·
设计制备具有高能量密度、高稳定性和低感度的化合物一直是含能材料领域的主要研究内容。在新型含能化合物的分子设计中,将不同的取代基通过桥联的方式进行连接,从而提高爆轰性能和稳定性,是一种行之有效的手段,其中以—(CH2)n
构造平面型的分子结构也是得到高密度,低感度的含能材料的方法之
本研究拟以—NH—为桥,连接两个富氮模块,形成平面型含能分子,同时在富氮模块上引入邻位的—NO2和—NH2,从而得到高能钝感的含能化合物。以6‑(3,5‑二甲基吡唑)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪(化合物1)为底物,与2,6‑二氨基‑3,5‑二硝基吡嗪(化合物2)在碱性条件下反应,合成了‑NH‑桥联的具有稠杂环体系的6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑1,2,4‑三唑[4,3‑b][1,2,4,5]四嗪(化合物3),该化合物含有邻位的—NO2和—NH2官能团。对该化合物的分子进行结构表征与晶体分析,研究其分子间堆积方式对化合物性能的影响,并且计算其爆轰性能,探究其作为含能材料的潜质。
Bruker Avance Ⅲ 500 MHz数字化核磁共振仪,DSC‑25型差示扫描量热仪,Thermo Nicolet AVATAR 370红外光谱仪,2000 Bruker‑AXS X‑射线单晶衍射仪,Vario MICRO cube Elementar Analyser元素分析仪,Micromeritics全自动气体置换法真密度仪ACCUPYCII1345,FSKM 10 BAM摩擦感度仪,BFH 12 BAM撞击感度仪。
碳酸钾(分析纯),出自阿拉丁;DMF,36%盐酸,乙腈,乙醚,均为分析纯,出自沪试;6‑(3,5‑二甲基吡唑)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪(1),2,6‑二氨基‑3,5‑二硝基吡嗪(2)参照文献[
合成过程如
Scheme 1 Synthetic route of compound 1 and 3
利用乙腈作为溶剂将6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑1,2,4‑三唑[4,3‑b][1,2,4,5]四嗪(化合物3)配制成饱和溶液,于室温下缓慢挥发得到符合测试标准的单晶。选取尺寸为0.19 mm×0.13 mm×0.06 mm的单晶于2000 Bruker‑AXS X‑射线单晶衍射仪上,采用经石墨单色化的MoKα射线(λ=0.143 m
3·CH3CN晶体的分子结构和堆积图分别为
图1 3·CH3CN分子结构图
Fig.1 Molecular structure of 3·CH3CN
从
图2 化合物3·CH3CN沿b轴的堆积方式
Fig.2 Packing diagram of 3·CH3CN viewed from b axis
图3 化合物3的分子间和分子内氢键
Fig.3 Inter‑/intra‑ molecular hydrogen bonds of compound 3
采用差示扫描量热仪研究化合物3的热稳定性(氮气气氛,密封盘,升温速率5 ℃·mi
图4 化合物3的DSC曲线(5 ℃·mi
Fig.4 DSC curve of 3 at 5 ℃·mi
根据所得的生成焓(757.2 kJ·mo
Note: Td is the thermal decomposition temperature (onset) under nitrogen gas (DSC, 5 ℃·mi
(1)含有氨基和硝基官能团的平面杂芳环化合物通常具有高能钝感的优异性能,再通过—NH—键桥联高氮的稠环结构,设计合成了一种具有平面型结构的含能化合物。
(2)以6‑(3,5‑二甲基吡唑)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪为底物,通过亲核取代反应得到6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪,并采用核磁、红外、元素分析和X射线单晶衍射进行结构表征,6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪分子属于单斜空间群P21/c,实测密度为1.70 g·c
(3)6‑(2,6‑二氨基‑3,5‑二硝基吡嗪)‑[1,2,4]三唑[4,3‑b][1,2,4,5]四嗪较高的分解温度(255
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