ELECTROCHEMICAL SULFUR-DIOXIDE REDUCTION AT SMOOTH PLATINUM-ELECTRODES IN MIXED-SOLVENTS

The reduction of sulfur dioxide was studied at platinum electrodes in sulfolane, acetonitrile, dimethylacetamide, and mixtures of these solv ents with lithium bromide and lithium perchlorate as the base electrol ytes. It was shown that the electron-donor and electron-acceptor prope rties of the solvents influence, both the electrochemical step and sub sequent reactions. The electrochemical step and the dimerization of th e primary radical-anions become slower with increasing basicity of the solvents. Anions having high donor power have an activating effect on the electrochemical step. The high sensitivity of the electrochemical system to the donor-acceptor properties of the medium can be used for a deliberate control of cathodic sulfur dioxide reduction.