关键词: Simons电化学氟化, CH₃SO₂F, 氟化过程机理

Abstract:

The characteristics and mechanism for the Simons electrochemical fluorination processes were investigated during the electrochemical fluorination of CH₃SO₂F to CF₃SO₂F. The results showed that the reaction mechanism for the electrochemical fluorination of organic compounds to organic fluorides was the same as that of chemical fluorination processes using fluorinating agents such as CoF₃. The electrochemical fluorination in anhydrous HF was a heterogeneous process, and nickel fluorides on the surface of the nickel anode played the role of a mediator in the Simons process to transfer oxidation potential from the anode to the substrate and fluorine from HF to the organic substance. Nickel fluorides were formed electrochemically on the surface of the nickel anode by oxidation of Ni in anhydrous HF to a high valence (with the oxidation stage more than +2) nickel fluorides. The fluorinating agents in electrochemical fluorination processes were NiF_n（n≥3）, high valences of nickel produced at the anode, which is much more reactivie than CoF₃ and instable under the experimental conditions. The decomposion of NiFn to F2 would take place, and NiF_n could also react with organic fluoride. Because F₂ is a strong fluorinating agent, NiF_n could be decomposed into low molecular weight organic compounds fluorinated products, leading to low current efficiency in process yield and by-products. Therefore, an effective method to improve the process is by increasing the molar ration of organic matter to NiF_n on the anode/electrolyte interface.