Electrocatalytic Dealkylation of Amines Mediated by Ferrocene

Abstract

The homogeneous catalytic oxidation of dicyclohexylamine (DCHA), N,N-dimethylcyclohexylamine (DMCHA) and N,N-dicyclohexylmethylamine (DCHMA) has been investigated in the presence of electrochemically generated ferrocenium ions as the catalyst. Mechanistic details for this electrocatalytic process have been scrutinized with the use of cyclic voltammetry, bulk electrolysis, and digital simulations techniques. A one-electron catalytic process between ferrocene and the respective amines was observed. The products obtained from bulk electrolysis were isolated and identified by FTIR, 1H and 13C NMR spectroscopy, and mass spectrometry. Both DCHMA and DMCHA proceed to yield a secondary amine product by the elimination of one methyl group. In the absence of this group, as in the case of DCHA, the cycloalkyl group is then eliminated. The catalytic efficiency and the second-order rate constants were estimated and found to follow the order DCHA ≪ DMCHA < DCHMA. The results presented in this work should open up a new avenue to achieve simple, low-cost, and efficient amine oxidation, which could be useful in several areas of chemistry.