Photothermal synergistic chlorination of ethylene carbonate in a solvent-free microchannel reactor

• This study established a selective C-H chlorination reaction system for ethylene carbonate (EC) through the synergistic photothermal effect of liquid chlorine and BPO initiator, effectively overcoming the bottleneck issues of prolonged reaction cycles and low chlorine resource utilization in traditional processes. Based on the solvent-free green synthesis concept, a novel preparation process for chlorinated ethylene carbonate (CEC) with inherent safety was developed, providing a feasible technical solution for large-scale production. • The adoption of a microchannel reactor enables precise manipulation of reaction feedstocks in a confined space, ensuring accurate reactions while avoiding back-mixing phenomena. Additionally, the excess heat generated during the process can be efficiently removed, creating reliable external conditions for improving product purity and significantly enhancing the yield and selectivity of the target product. This not only accelerates the chlorination process but also mitigates the safety concerns associated with liquid chlorine to some extent. • Using BPO as a radical initiator and Cl₂ as the chlorine source, the chlorination of EC to synthesize CEC was successfully carried out in a microchannel reactor under UV irradiation. The optimal process parameters were determined to be a reaction temperature of 85°C, Cl₂ to EC molar ratio of 0.48:1, residence time of 18.5 min, three cycles, wavelength of 254 nm, light intensity of 120 W, and BPO initiator concentration of 1.5 wt%. Under these conditions, the EC conversion reached 99.5%, and the CEC yield was 84.1%. The photothermal chlorination of ethylene carbonate (EC) using liquid chlorine and benzoyl peroxide (BPO) initiator offers a green approach to C-H chlorination. However, batch reactors present challenges including prolonged reaction times and low chlorine utilization efficiency. These limitations may be effectively overcome through microchannel reactor technology. This study developed a green, safe process for selectively chlorinating EC to chloroethylene carbonate (CEC). In the microchannel reactor, liquid chlorine served as chlorinating agent and BPO as initiator under UV irradiation. After parameter optimization, the optimal conditions achieved 99.5% EC conversion and 84.1% CEC yield.