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 TFAA concentration and decreases with the increasing of CPL concentration. The in-situ FTIR is adopted to study the reaction mechanism and quantitative equilibrium relationship of CPL with TFAA. Based on the experimental results, a reaction mechanism is proposed and a kinetics model is established, which is in good agreement with the experimental data. The TFAA/TFA catalytic system allows high conversion and reaction rate compared with other organic acids.

An efficient method for the Beckmann rearrangement of cyclohexanone oxime (CHO) catalyzed by trifluoroacetic anhydride (TFAA) is proposed in this work. The effects of experimental parameters on the reaction rate are studied, including CHO concentration, TFAA/CHO ratio, temperature, and CPL concentration. The reaction rate shows a linear relationship with TFAA/CHO ratio and reduces with the increasing of CPL concentration. Based on the experimental data and the study of in-situ FTIR, a reaction mechanism is proposed and the equilibrium relationship between CPL and TFAA is established. A rate constant model is developed and is in good agreement with the experimental results. The TFAA/TFA catalytic system allows high conversion and reaction rate compared with other organic acids.

The nitration of chlorobenzene with concentrated mixed acids is a fast and highly exothermic process, which suffers from considerable mass transfer resistance and poor heat transfer rates. The reaction kinetics has not been thoroughly reported before. In this work, a continuous-flow microreactor system and a homogeneous reaction condition were proposed to obtain accurate chlorobenzene nitration kinetics data at high mixed acid concentrations. A general model for predicting the observed reaction rate constants was established. With a new method for estimating the equilibria associated with HNO3 in aqueous sulfuric acid, the rate constants based on nitronium ion and activation energies were obtained. Compared with batch reactors, the continuous-flow microreactor system allows for a sufficient heat transfer efficiency and accurate residence time control, making it possible to study the reaction performance more quickly and sensitively. This work may provide a reliable reference for the kinetic study of similar processes.