An atom-efficient electrosynthesis strategy for organic halides

Existing organic halide synthesis routes typically employ elemental halogens ( X 2 , X = Cl or Br), leading to low atom economy and significant environmental pollution. In this work, we developed an atom efficient electrosynthesis and separation strategy for halogenation reagents — N -chlorosuccinimide (NCS) and N -bromosuccinimide (NBS) — at high current densities. Faradic efficiency (FE) of 91.0% and 81.3% was achieved for NCS and NBS generation on RuO x /TiO 2 /Ti in a batch cell, respectively. Electrosynthesis of NCS likely involves both heterogeneous catalytic and homogeneous tandem pathways, while NBS is likely formed in a Langmuir-Hinshelwood mechanism with a proton-coupled electron transfer as the rate-determining step. A coupled continuous electrocatalytic synthesis and in situ separation setup was developed for the efficient production of NCS and NBS, which yielded 0.77 g of NCS in 12000 s and 0.81 g of NBS in 15000 s, both with relative purity exceeding 95%. The halogenation of acetone using NCS and NBS enabled gram-scale production of the key intermediate in organic synthesis, 1-halogenacetone, with over 95% recovery of succinimide. This study developed an atom-efficient electrochemical strategy for synthesizing high atom-efficiency halogenation reagents-NCS and NBS-at high current density, achieving 91.0% and 81.3% FE respectively. A continuous electrosynthesis system can produce garm-scale NCS and NBS with > 95% purity.