Electrochemical Assessment of EC and ECE Mechanisms for Caffeic Acid in the Presence of Aromatic Amines

In this work, electrochemical behavior of caffeic acid (CA) in the absence and presence of aromatic amines such as 4-amino-1,3- dimethyluracil (4A-DMU), p-toluidine (p-TI) and sulfacetamide (SA) has been investigated using cyclic voltammetry technique in 0.15 M sodium acetate solution/ethanol (80:20, v/v) mixture. The effect of different parameters such as concentration and scan rate indicated that the oxidation mechanism of caffeic acid (CA) in the presence of aromatic amines can be EC and ECE. At the working electrode surface, CA is oxidized to correponding o-benzoquinone (CAOX) through two electrons and two protons process. The Michael-type addition reaction has occurred between o-benzoquinone and aromatic amines. In the second cycle, compared to CA oxidation peak, a new oxidation peak appear in negative potentials because of the electron-donating properties of amines. The cyclic voltammetry technique can recognize chemical and electrochemical processes in solution and electrode surface, respectively.