Abstract: Existing organic halide synthesis routes typically employ elemental halogens (X₂, X = Cl or Br), leading to low atom economy and significant environmental pollution. In this work, we developed an atom efficient electrosynthetic 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/TiO₂/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-determing 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 syhthesis, 1-halogenacetone, with over 95% recovery of succinimide.

Key words: Electrocatalysis, Process intensification, Halogenation reaction, Organic halides synthesis, N-chlorosuccinimide, N-bromosuccinimide