Synthesis of Benzoic Acids from Electrochemically Reduced CO2 Using Heterogeneous Catalysts

A method for the synthesis of benzoic acids from aryl iodides using two of the most abundant and sustainable feedstocks, carbon dioxide (CO2) and water, is disclosed. Central to this method is an effective and selective electrochemical reduction of CO2 to CO, which mitigates unwanted dehalogenation reactions occurring when H2 is produced via the hydrogen evolution reaction (HER). In a 3-compartment set-up, CO2 was reduced to CO electrochemically by using a surface-modified silver electrode in aqueous electrolyte. The ex-situ generated CO further underwent hydroxycarbonylation of aryl iodides by MOF-supported palladium catalyst in excellent yields at room temperature. The method avoids the direct handling of hazardous CO gas and gives a wide range of benzoic acid derivatives. Both components of the tandem system can be recycled for several consecutive runs while keeping a high catalytic activity.