Electrochemical Synthesis of Aryl Chlorides Using HCl as the Chlorine Source

Hydrochloric acid (HCl) is abundantly generated as the byproduct in the chemical industry. The recycling of chloride from HCl is related to intensive energy input and resource consumption. European Commission Joint Research Centre stated that the production and utilization of chlorine are indicative of the development level of the chemical industry. To utilize HCl in a green way, an unprecedented, straightforward, and simple electrosynthesis method has been employed to produce chlorinated aromatics. The control experiments indicated that the reaction underwent a free radical pathway and that the mass transfer was crucial for the reaction. Further, a microchannel flow electroreactor was further used to scale up the reaction. To overcome the hydrophobic obstacle of the graphite electrode surface, a hydrophilic modification method with nitric acid was used. After the modification, the content of the O element of the graphite increased from 1.1 to 2.3%, the C–O–C unit increased from 10.9 to 16.2%, and the O–C═O unit increased from 27.1 to 28.2%. Thus, the desired product was afforded with satisfactory yields under the modified electrode.