Electrosynthesis of hindered alkyl diamines: evidence for an electrocatalytic anodic mechanism

The electrosynthesis of highly hindered secondary alkyl diamines through the formation of C-N bonds has been successfully performed in one-pot under mild conditions using an environmentally friendly method. The electrochemical behavior of four hindered secondary alkyl amines (di-tert-butylamine (1), tert-amyl-tert-butylamine (2), di-tert-amylamine (3) and tert-amyl-tert-octylamine (4)) is described. Effects not only of the initial concentration of the corresponding di-tert-akylamine but also of the time on the initial oxidation scan are reported for the first time for the electrochemical behavior of an aliphatic amine. Moreover, valuable mechanistic information has been provided from analysis of the intermediate species and final products generated when electrochemical oxidation was performed. An electrocatalytic mechanism based on the propagation of free radical species leading to highly hindered diamines has been tentatively proposed. The key role played by the radical cation as the intermediate initiator involved in the subsequent propagation cycle has been demonstrated.