Electrochemical Reactor Design and Operation for the Simons Fluorination of Methyl Sulfonyl Fluoride

The key problems in the process for the industrialization of the Simons electrochemical fluorination of methyl sulfonyl fluoride (CH 3 SO 2 F) to trifluorometan-sulfonyl fluoride (CF 3 SO 2 F), such as reactor design and optimization of the process are discussed. Based on recent developments, the nickel fluorinating agent mediated mechanism in the Simons electrochemical fluorination of CH 3 SO 2 F to CF 3 SO 2 F is proposed. It is shown that the yield and current efficiency of the product mainly depend on the operating current density and the mass tranport rate. Thus useful rules to optimize the process of electrochemical fluorination in anhydrous hydrogen fluoride (HF) for reactor design and operation for the Simons fluorination of CH 3 SO 2 F are formulated for the solid-liquid heterogeneous reaction system. In order to improve the yield and current efficiency as well as reduce the produce rate of the free fluorine (F 2 ), an effective method is proposed to improve the mass transfer and reduce current density. A three-dimensional electrode electrochemical reactors is designed with a large specific surface area, which can significantly reduce the operating intrinsic current density, and effectively improve mass transfer with a large specific surface area, increase the concentrations of CH 3 SO 2 F on the reaction surface of the anode. The three-dimensional electrode electrochemical reactors fundamentally reduce the likelihood of fluoride chemical reaction, and raise the production efficiency of electrochemical reactor. The experimental result shows that the product molar yield is more than 85% and current efficiency is more than 90% using 20 mesh metal nickel net as anode materials at 15-25% CH 3 SO 2 F in HF, operation temperature 0 to 15 °C and apparent operating current density between 1000-1600 A/m 2 . Key words : Simons electrochemical fluorination, electrochemical reactor design, methyl sulfonyl fluoride, trifluorometansulfonyl fluoride.