Improved efficiency of continuous conversion of alcohols to chlorides in flow microreactors with DESs/HCl via predictive fluid model

Abstract

The efficient and safe synthesis of chlorides is attractive in pharmaceutical chemicals yet presents challenges. Herein, a novel route has been developed for the conversion of alcohols into the corresponding alkyl chlorides in continuous flow microreactor. Meanwhile, the system utilizes deep eutectic solvents (DESs) hydrochloride solutions (DESs/HCl) as both solvents and catalysts for this reaction. The results suggest that the premixed mode continuous flow microreactor using DESs/HCl can significantly improve the harsh reaction conditions in the synthesis reaction of chlorides. Furthermore, tuning the HCl concentration under 383 K and 30 min conditions significantly increased the yields of n-Butanol chloride and Benzyl chloride to 86 % and 98 %, respectively. This work shows the great application potential of the continuous flow microreactor combined with DESs/HCl to convert alcohols into corresponding alkyl chlorides or aryl chlorides. Besides, the fluid model and HCl absorption kinetics were established based on the calculated diffusion coefficients (D_R), Damköhler number (Da), Bodenstein number (Bo), residence time (τ), and experimental results. The flow model of the mixture of DESs/HCl and alcohols in the microreactor was a plug flow, which is beneficial for improving the efficiency of this reaction.