Dimethylpyrrolidinium amalgam formation and catalysis of organic electroreductions

Abstract The cathodic reduction of several tetraalkylanunonium cations on mercury in DMF with 0.1 M tetrabutylainmonium fluoroborate as the supporting electrolyte was investigated and dimethylpyrrolidinium (DMP + ) was chosen as a representative for an intensive study. It was shown that DMP + reacts by a reversible one-electron process forming an insoluble material best described as an amalgam. The material has a half life of 6.3 h at 5°C and consequently reacts with the solvent, yielding dimethylamine and regenerating DMP + . It was also shown that DMP + is a catalyst for the reduction of cyclohexanone. The catalytic nature of the DMP + reactions with DMF and cyclohexanone and the possible involvement of reduced tetraalkylammonium intermediates in other organic electroreductions are discussed.