Electrosynthesis of adiponitrile in undivided cells

Abstract

It has been shown that adiponitrile can be synthesized in undivided cells under favourable conditions. Because of strong decomposition of the quaternary ammonium salt support electrolyte, its concentration must be kept at a very low level. To avoid excessive resistance of the cell, the distance between the electrodes must then be smaller than 0·5 mm. We have developed various types of such cells. The ‘capillary gap cell’ is simple in design and can be readily scaled up. Continuous operation is possible. Yields of about 90% of adiponitrile have been obtained. The energy consumption is less than 3 kWh/kg product. Work up of the solutions is greatly facilitated by the low salt concentrations. It has been shown that the anodic oxidation of isopropanol, which is used as cosolvent, is strongly influenced by the acrylonitrile present. A substantial portion of the isopropanol is oxidized to CO₂.