tetraethylammonium p-toluenesulfonate 24 h; Ambient temperatureelectrolysis in a divided cell, immersed platinum foil electrodes, a constant applied voltage of 3 V (cell voltage: ca. 1.3 V vs. Ag/AgCl; current: 2.0-2.5 mA);

With  toluene-4-sulfonic acid in  benzene  Heating;