Low-Temperature Flow Electrolysis for Efficient Trichloromethylation Aided by Electrogenerated Base

Abstract

This study introduces a novel low-temperature electrochemical flow reactor for the efficient trichloromethylation of benzaldehyde using electrogenerated bases (EGBs). The setup achieved precise temperature control by leveraging a Peltier-cooled system and a divided flow reactor with carbon-felt electrodes without requiring external cooling baths. Optimization of reaction parameters, including flow rate, temperature, and charge passed, resulted in a maximum yield of 67 % for 2,2,2-trichloro-1-phenylethanol, demonstrating significantly enhanced stability and reactivity of EGBs. This system exhibits a productivity of 1.01 mmol h⁻¹, which is 6.7 times higher than that of a prior microflow reactor approach, and successfully scales up to reactions involving 5 mmol of substrate. Cooling was identified as a critical factor in stabilizing the reactive intermediates, while further experiments confirmed the inefficacy of external cooling components alone. This robust and scalable reactor design highlights the potential for advancing low-temperature electrochemical synthesis and unlocking new reaction pathways.