Development of a Split Bipolar Electrode System for Electrochemical Fluorination of Triphenylmethane

To overcome the problem of electrochemical fluorination methods using a large amount of supporting electrolytes and fluorine sources, we employed a split bipolar electrode (s‐BPE) system, in which electrode reactions occur in a low concentration of supporting electrolyte and electricity is monitored. We optimized the electrochemical parameters for the s‐BPE system using a U‐shaped electrochemical cell and investigated the electrochemical fluorination of triphenylmethane as a model substrate in the presence of potassium fluoride (KF) or cesium fluoride (CsF) as a supporting electrolyte and a fluorine source dissolved by the help of poly(ethylene glycol) (PEG) additive. The fluorination of triphenylphoshine was also examined under the optimized conditions. Electrochemical fluorination of triphenylmethane is carried out using a low concentration (1 mM) of CsF on a split bipolar electrode (s‐BPE) system, in which currents and charges passed through the BPE could be monitored. Such an operation in low concentration of supporting electrolyte for organic electosynthesis is an ideal method in terms of waste reduction and easy separation process.