Low-migratory ionic ferrocene-based burning rate catalysts with high combustion catalytic efficiency
Low-migratory ionic ferrocene-based burning rate catalysts with high combustion catalytic efficiency
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DOI：
10.1039/c4nj01216j
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发表时间：
2015
影响因子：
3.3
通讯作者：
Xuelin Liu;Wei‐qiang Zhang;Guofang Zhang;Ziwei Gao
中科院分区：
文献类型：
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作者：
Xuelin Liu;Wei‐qiang Zhang;Guofang Zhang;Ziwei Gao
烷基取代二茂铁对复合固体推进剂的燃烧具有良好的催化作用。然而，这些非极性和挥发性的二茂铁，迁移到推进剂的表面，这将改变设计的燃烧参数，更严重的是引起意外爆炸。为了解决这一问题，合成了12种含有硝酸根和苦味酸根的甲基咪唑和甲基三唑取代基的二茂铁衍生物作为新型离子型二茂铁基燃速催化剂。化合物的结构经1HNMR、13 CNMR和元素分析确证。其中10个通过单晶X射线衍射进行了表征。化合物2和3分别属于单斜晶系P2（1）/n和P2（1）/c空间群。化合物4·H2O、6·12 H2O、8-10和12的晶体结构属于三斜晶系空间群P。化合物7和11的晶体结构分别属于Pna 21和Pna 2（1）斜方晶系空间群。循环伏安法研究表明，所有的化合物表现出准可逆的氧化还原系统。迁移研究证实，这些离子型二茂铁的迁移比2，2-双（乙基二茂铁基）丙烷慢得多。化合物的迁移趋势取决于离子二茂铁的分子结构，并且杂环中较短的烷基链长度导致较慢的迁移速率。通过TG和DSC分析确定了它们的高热稳定性（峰值温度>172 °C）。采用DSC方法研究了新型燃速催化剂对高氯酸铵（AP）的热降解性能。当硝酸盐（1-6）和苦味酸盐（7-12）分别为4wt%和5wt%时，AP的分解峰温度显著左移，放热显著增加。在其阳离子中具有三唑环的离子化合物的催化活性高于其具有咪唑环的相应类似物，并且硝酸盐的催化活性通常高于其苦味酸盐对应物。
Alkyl substituted ferrocenes can catalyze the burning of composited solid propellants efficiently. These non-polar and volatile ferrocenes, however, migrate to the surface of the propellants during prolonged storage, which would alter the designed burning parameters, and more seriously cause unexpected explosions. To tackle this problem, twelve ionic ferrocene derivatives bearing methylimidazolium and methyltriazolium substituents with nitrate and picrate anions as new ionic ferrocene-based burning rate catalysts were synthesized. The compounds were fully characterized by 1H NMR, 13C NMR and elemental analysis. Ten of them were characterized by single-crystal X-ray diffraction. Compounds 2 and 3 crystallize in the monoclinic space group P2(1)/n and P2(1)/c, respectively. Compounds 4·H2O, 6·1/2H2O, 8–10 and 12 crystallize in the triclinic space group P. Compounds 7 and 11 crystallize in the orthorhombic space group Pna21 and Pna2(1), respectively. Cyclic voltammetry investigations revealed that all the compounds exhibit quasi-reversible redox systems. Migration studies confirmed that the migration of these ionic ferrocenes is much slower than that of 2,2-bis(ethylferrocenyl)propane. The migration trend of the compounds is dependent on molecular structures of the ionic ferrocenes and that shorter alkyl chain lengths in the heterocyclic rings lead to slower migration rates. Their high thermal stability was determined by TG and DSC analyses (peak temperatures >172 °C). The thermal degradation of ammonium perchlorate (AP) catalyzed by the new burning-rate catalysts was evaluated by DSC methods. In the presence of nitrate (1–6) in 4 wt% or picrate (7–12) in 5 wt%, the peak decomposition temperature of AP shifts left significantly while the released heat increases dramatically. The catalytic activity of an ionic compound with a triazole ring in its cation is higher than its corresponding analog with an imidazole ring and the catalytic activity of a nitrate is generally higher than its picrate counterpart.