Mechanistic Study and Computational Analysis of the Electrochemical Oxidation of Caffeic Acid in the Presence of Different Nucleophiles

Beiginejad, Hadi; Shojaeie, Seyed Abdollah

doi:10.22034/abec.2025.739011

Mechanistic Study and Computational Analysis of the Electrochemical Oxidation of Caffeic Acid in the Presence of Different Nucleophiles

Document Type : Original Article

Authors

Hadi Beiginejad

Seyed Abdollah Shojaeie

Department of Applied Chemistry, Faculty of Science, Malayer University, Malayer 65174, Iran

10.22034/abec.2025.739011

Abstract

The electrochemical oxidation of caffeic acid in the presence of p-toluenesulfinic acid, methyl-Meldrum’s acid, phenyl-Meldrum’s acid, barbituric acid, and Meldrum’s acid as nucleophiles was investigated using experimental and theoretical approaches. Experimental studies were conducted using cyclic voltammetry, linear sweep voltammetry, and controlled-potential coulometry. Theoretical calculations were performed using density functional theory (DFT) at the BP86 level with the 6-31G (d,p) basis set. The results indicate that the electrochemical oxidation of caffeic acid in the presence of p-toluenesulfinic acid, methyl-Meldrum’s acid, and phenyl-Meldrum’s acid follows an EC mechanism, where E denotes an electrochemical step and C represents a subsequent chemical reaction. In contrast, the oxidation of caffeic acid in the presence of barbituric acid and Meldrum’s acid proceeds via an ECEC mechanism. To elucidate the origin of these mechanistic differences, computational studies were conducted. The results obtained using a general thermodynamic cycle demonstrate that the reaction pathway depends on the Gibbs free energy change (ΔG) of the electrochemical oxidation step, which determines whether the species generated at the electrode surface undergoes subsequent electrochemical or chemical reactions.

Keywords

Electrochemical oxidation

Controlled-potential coulometry

Caffeic acid

&Delta

G_tot

Subjects