ELECTROCHEMICAL REDUCTION OF SUBSTITUTED ANTHRACENES

A systematic investigation of the electrochemical reduction of substituted anthracenes in N,N-dimethylformamide has unveiled the reductive properties of the aromatic compounds. For the anthracenes with a reversible first reduction, the redox potential exhibits linearity vs sigma value of the Hammett equation. For anthracenes with an irreversible first reduction, the electron transfer and chemical reaction occur via either a sequential or a concerted pathway. When the irreversible first reduction occurs at a potential more negative than E1/2 calculated from the sigma value, the reaction occurs via a sequential pathway, such as for 9-chloroanthracene. When the irreversible first reduction occurs at a potential more positive than the expected E1/2, the reaction occurs via a concerted mechanism of electron transfer and bond breaking, such as for 9-chloromethylanthracene. The displacement of the halide results in the parent polyaromatic hydrocarbons, as indicated by the spectroelectrochemical method.