Electrochemical behavior of cinnamic acid associates on carbositall electrode in dimethylformamide in the presence of external proton donors

The electroreduction (ER) of trans-cinnamic acid (CA) and its associates in an aprotic solvent, dimethylformamide (DMF), in the presence of proton donors: weak (H2O) and moderate (acetic acid AcOH) and also with addition of R4NOH (R = Et; Bu) to the CA solution in DMF is studied by the methods of cyclic voltammetry (CVA) and chronoamperometry on a cathode with the high hydrogen overpotential—carbositall. The electrochemical behavior of AcOH in DMF and in the mixture 16% H2O–DMF is examined. The results obtained show that CA associates in DMF can include AcOH (or H2O) molecules to form sufficiently stable mixed associates. The anionic species that appear at the reduction of such associates decompose with abstraction of the original CA, which results in the appearance of inverted, i.e., cathodic peaks at ca. -2.0 V in the anodic CVA branch. A comparative study of methyl cinnamate is carried out under similar conditions on the carbositall electrode. In contrast to CA, the behavior of methyl cinnamate in DMF in the presence of a proton donor (AcOH) corresponds to the classical ER scheme for α,β-unsaturated esters.