低场MRI原位研究离子液体合成及相态变化

离子液体作为一个平台化合物已经在诸多领域得到广泛应用，但离子液体的生产成本仍然是限制其进一步工业化推广的瓶颈之一。深入研究反应动力学、反应传递耦合规律对优化离子液体合成工艺/关键设备，降低大规模离子液体制备成本至关重要。本研究用一个原位低场磁共振成像(MRI)设备实时监测ILs合成过程中的反应动力学和相态变化。通过建立双组分分析模型，即1H低场核磁共振(LF-NMR)弛豫法对反应体系中的各个组分进行定量分析，并采集MRI图像记录相位分离和倒置过程，系统考察了卤代烷烃的链长、卤素种类、搅拌速度、反应温度等对咪唑类离子液体反应动力学的影响规律。对溴丁烷、甲基咪唑合成溴代1-丁基-3-甲基咪唑类离子液体合成过程中相态变化进行了实时动态观测。本研究为检测离子液体反应过程及有机溶剂中离子液体的残余量提供一种快速、便利、无损的检测方法，有望利用低场MRI对离子液体系统中传质和反应动力学的结合研究做进一步探索。

Studies on reaction kinetics and phase changes during the synthesis of ionic liquids using an in-situ low-field MRI spectrometer

Ionic liquids (ILs) have a wide range of applications due to their many beneficial properties. However, the production cost of ILs is still high, which is limiting further industrialization. Hence, in-depth studies of the reaction kinetics and phase changes are essential to optimize the synthesis processes for ILs and the key equipment involved. An in-situ low-field magnetic resonance imaging (MRI) device was used to monitor the reaction kinetics and phase changes that occurred during the synthesis of ILs in real time. Quantitative analysis of the ILs components in the reaction system was performed using an established two-component analysis model via 1H low-field nuclear magnetic resonance (LF-NMR) relaxometry data. This analysis allowed investigating the effects of haloalkanes chain length, halogen species, stirring speed, and temperature on the reaction kinetics of the synthesis of imidazole-based ILs. Through the detected spatiotemporal T2 distributions of the phases state during the solvent-free synthesis of the 1-buty-3-methylimidazole (C4mim]Br) IL by reacting 1-bromobutane (BuBr) with 1-methylimidazole (MIM). This study provided a set of fast, convenient, and non-destructive technical means for the detection of different aspects of the synthesis of ILs, including detection of the residual amount of ILs in organic solvents. Meanwhile, further exploration of using low-field MRI to study the combined mass transfer and reaction kinetics in ILs systems as the studied ones could be expected.