The kinetics of the Beckmann rearrangement of cyclohexanone oxime (CHO) catalyzed by trifluoroacetic anhydride (TFAA) and trifluoroacetic acid (TFA) is proposed in this work. The effects of experimental parameters on the reaction rate are studied in microreactors, including CHO concentration, TFAA concentration, temperature, and caprolactam (CPL) concentration. The reaction is verified as first-order, and the reaction rate shows a linear relationship with the TFAA concentration and decreases with increasing CPL concentration. In situ Fourier transform infrared spectroscopy (FTIR) is adopted to study the reaction mechanism and quantitative equilibrium relationship of CPL with TFAA. The reaction enthalpy between CPL and TFAA is determined as −17.4 kJ mol^–1. Based on the experimental results, a reaction mechanism is proposed, and a kinetic model is established, which is in good agreement with the experimental data. The rate-determining step is identified to be the rearrangement of trifluoroacetyl cyclohexanone oxime to trifluoroacetyl caprolactam, and the activation energy is determined as 87.7 kJ mol^–1. The TFAA/TFA catalytic system allows high conversion and reaction rate compared with other organic acids.

中文翻译：

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三氟乙酸酐在微反应器中有机催化贝克曼重排环己酮肟

本文提出了三氟乙酸酐 (TFAA) 和三氟乙酸 (TFA) 催化的环己酮肟 (CHO) 的贝克曼重排动力学。在微反应器中研究了实验参数对反应速率的影响，包括 CHO 浓度、TFAA 浓度、温度和己内酰胺 (CPL) 浓度。该反应被验证为一级反应，反应速率与TFAA浓度呈线性关系，并随着CPL浓度的增加而降低。采用原位傅里叶变换红外光谱（FTIR）研究了CPL与TFAA的反应机理和定量平衡关系。CPL 和 TFAA 之间的反应焓确定为 -17.4 kJ mol ^–1. 根据实验结果提出了反应机理，建立了与实验数据吻合较好的动力学模型。确定速率的步骤是三氟乙酰环己酮肟重排为三氟乙酰己内酰胺，活化能确定为 87.7 kJ mol ^–1。与其他有机酸相比，TFAA/TFA 催化体系具有较高的转化率和反应速率。