Paired Electrosynthesis at Interdigitated Microband Array Electrodes without Intentionally Added ElectrolyteC-C Coupling of Dicyanobenzenes with Methanol

The formation of substituted benzyl alcohols from dicyanobenzenes and methanol (C-C coupling) is demonstrated as a model system for paired electrosynthesis and investigated at interdigitated microband array electrodes in a microreactor with/without intentionally added supporting electrolyte. A Pt-Pt microband array with 5 μm bands separated by 5 μm gaps is employed in a dimethyl sulfoxide (DMSO) solvent. Yields are optimized to approximately 50% at the point of 100% conversion. The mechanism is investigated by employing isotope labeling (CD ₃OD, CH ₃OD, d ₆-DMSO, ¹³CH ₃OH). The methylene group ( ¹²C or ¹³C) is obtained with H ₂, D ₂, and DH substitution patterns, and a hypothesis for a corresponding mechanism is discussed aided with density functional theory (DFT) calculations. Implications for sustainable electrosynthesis at paired microband electrodes are discussed.