Traces of Elements in the Electrochemical Reductive Amination of Acetone: Uncovering Bi as Substitute for Pb

Abstract

ABSTRACT Amines are broadly utilized as solvents, pharmaceuticals, herbicides, or materials. A benign synthesis route to produce amines from carbonylic substrates is the electrochemical reductive amination, whereby electrons combined with a green proton source like water serve as formal reducing agent. Surprisingly, investigating various p‐block elements as mediator for the electrochemical conversion of acetone in presence of methylamine revealed that only elements of the sixth period show an activity. Building up on these findings and the general low toxicity of Bi compared to Tl or Pb, the electrochemical hydrogenation of N ‐methylpropan‐2‐imine was optimized by studying the effect of Bi concentration, reaction temperature, and cathode material. Thus, this work highlights Bi as innovative mediator for the electrochemical reductive amination, whereby in presence of a few ppm‐amounts of Bi at ambient temperatures high amine yields are achievable.