Electrochemical Reduction of 4-Nitrobenzyl Phenyl Thioether for Activation and Capture of CO2

Altres ajuts: Acord transformatiu CRUE-CSICIn this work, a new simple molecule, 4-nitrobenzyl phenyl thioether (1), is prepared and used for controlling and tuning CO reactivity in function of the electrode potential. The first part of the study is devoted to determining the electrochemical reduction mechanism of 1 in N,N-dimethylformamide under nitrogen. The compound shows a first reversible one-electron transfer process, whereas the reaction cleavage of the C−S bond takes place after a second electron transfer process through a stepwise mechanism (thermodynamic and kinetic parameters are conveniently determined). In the second part of the study, the inert atmosphere was replaced by a CO atmosphere. At low potential values, compound 1 acts as a redox mediator that allows the reduction of CO at ca. −1.2 V vs. SCE. The electrochemical generation of 1 at more negative potential values leads to a C−S bond cleavage reaction that yields the corresponding nitrobenzyl and thiosulfate anions, which react with CO. The nitro aromatic anion derivative makes it possible to obtain electrocarboxylated derivatives, whereas the thiophenolate anion captures CO reversibly. Hence, this research opens a new way of tuning and controlling the reaction processes associated with CO from homogenous catalysis at low negative potentials, to electrocarboxylation processes passing to CO reversible electrochemically triggered adsorption processes