Fig. 3
From: Scalable carbon dioxide electroreduction coupled to carbonylation chemistry
Design of electrochemical CO2 reduction equipment, precision studies for CO production and adaptation to a Pd-catalysed carbonylative coupling. a The individual parts include (i) a double chamber reactor, (ii) silicon and Teflon seals with appropriate holes for electrodes, (iii) lids for the two chambers, (iv) stainless-steel working electrode (surface area = 24 cm2) and counter electrode (surface area = 7.5 cm2) separated by a Teflon spacer, (v) galvanostat (ElectroWare), (vi) molecular electrocatalyst, FeTPP, for CO2 reduction and (vii) the Buchwald 4th generation Pd(0)-precatalyst (Xantphos Pd G4) for aminocarbonylation. b The whole set-up assembled and running. c Illustration of reaction conditions for the CO2 reduction to CO and the subsequent aminocarbonylation between aryl iodide 2 and amine 3 for the preparation of moclobemide 1. d Individual reactions for the precision studies were achieved with 3.0 mmol aryl iodide, 6.0 mmol amine, 5 mol% Xantphos Pd G4, and 6.0 mmol DABCO in the chemical reaction chamber, and CO2 saturated 0.1 M TBABF4/DMF in the electrochemical chamber. Reactions were run with the ElectroWare set to prepare from 0.25, 0.5, 1.0, 1.5, 2.0 to 2.5 mmol CO. The yield of moclobemide produced was determined by high-performance liquid chromatography (HPLC) analysis in comparison to an internal standard (Supplementary Methods). The error bars represent the s.d. for two independent measurements. e Demonstration of the reusability of the same set-up as employed in d by repeating the reaction sequence and analysis multiple times. The ElectroWare was set to produce 0.5 mmol CO and the yield of the moclobemide (orange column) generated was determined by HPLC analysis of an aliquot from the chemical reaction chamber. After each experiment, the electrodes were removed and cleaned. Some minor reduction of 1-chloro-4-iodobenzene (2) to chlorobenzene (blue column) was observed for runs 3–5
