Scaling out of electrolyte free electrosynthesis in a micro-gap flow cell

The electro-reductive coupling of activated olefins and benzyl bromide derivatives has been selected to compare the performance of single and multiple channel (scaled-out) micro-gap electrochemical flow reactors. Two working electrode configurations were evaluated; in the first a single set of electrodes was used in conjunction with a multiple flow manifold to give two and four separate flow channels; in the second independent electrodes were used within the same flow manifold. Problems with shunt currents and Joule heating in the first configuration meant that only the second configuration was reliable, giving results comparable to those obtained for the single flow cell. Excellent yields of the coupling products such as 2-benzyl-succinic acid dimethyl ester and derivatives were obtained. This demonstrates micro reactor scale-out for unsupported electrosyntheses.