Thomas Anna E, Chambreau Steven D, Redeker Neil D, Esparza Alan A, Shafirovich Evgeny, Ribbeck Tatjana, Sprenger Jan A P, Finze Maik, Vaghjiani Ghanshyam L
Department of Aeronautics and Astronautics , Stanford University , Stanford , California 94305 , United States.
ERC Inc. , Air Force Research Laboratory, AFRL/RQRP , Edwards Air Force Base , California 93524 , United States.
J Phys Chem A. 2020 Feb 6;124(5):864-874. doi: 10.1021/acs.jpca.9b09242. Epub 2020 Jan 24.
In this study, in situ infrared spectroscopy techniques and thermogravimetric analysis coupled with mass spectrometry (TGA-MS) are employed to characterize the reactivity of the ionic liquid, 1-butyl-3-methylimidazolium dicyanoborohydride (BMIMDCBH), in comparison to the well-characterized 1-butyl-3-methylimidazolium dicyanamide (BMIMDCA) ionic liquid. TGA measurements determined the enthalpy of vaporization (Δ) to be 112.7 ± 12.3 kJ/mol at 298 K. A rapid scan Fourier transform infrared spectrometer was used to obtain vibrational information useful in tracking the appearance and disappearance of species in the hypergolic reactions of BMIMDCBH and BMIMDCA with white fuming nitric acid (WFNA) and in the thermal decomposition of these energetic ionic liquids. Attenuated total reflectance measurements recorded the infrared spectra of the reactant sample (BMIMDCBH) and the liquid reaction products after reacting with WFNA. Computational chemistry efforts, aided by the experimental results, were used to propose key reaction pathways leading to the hypergolic ignition of BMIMDCBH + WFNA. Experimental results indicate that the hypergolic reaction of BMIMDCBH with WFNA generates both common and unique intermediates as compared to previous BMIMDCA + WFNA investigations: nitrous oxide was generated during both hypergolic reactions indicating that it may play a crucial role in the hypergolic ignition process, NO was generated in significantly higher concentrations for BMIMDCBH than for BMIMDCA, CO was only generated for BMIMDCA, and HCN was only generated during thermal decomposition and hypergolic ignition of BMIMDCBH.
在本研究中，采用原位红外光谱技术以及热重分析与质谱联用（TGA-MS）来表征离子液体1-丁基-3-甲基咪唑二氰基硼氢化物（BMIMDCBH）的反应活性，并与已充分表征的1-丁基-3-甲基咪唑二氰胺（BMIMDCA）离子液体进行比较。TGA测量确定在298K时蒸发焓（Δ）为112.7±12.3kJ/mol。使用快速扫描傅里叶变换红外光谱仪获取振动信息，这些信息有助于追踪BMIMDCBH和BMIMDCA与发烟硝酸（WFNA）发生自燃反应时物质的出现和消失情况，以及这些含能离子液体的热分解过程。衰减全反射测量记录了反应物样品（BMIMDCBH）以及与WFNA反应后的液体反应产物的红外光谱。借助实验结果，通过计算化学方法来推测导致BMIMDCBH + WFNA自燃点火的关键反应途径。实验结果表明，与之前对BMIMDCA + WFNA的研究相比，BMIMDCBH与WFNA的自燃反应产生了一些常见和独特的中间体：两种自燃反应过程中均产生了一氧化二氮，这表明它可能在自燃点火过程中起关键作用；BMIMDCBH产生的NO浓度明显高于BMIMDCA；CO仅在BMIMDCA反应中产生；HCN仅在BMIMDCBH的热分解和自燃点火过程中产生。
