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Electrochemical oxidation of some p-aminophenol derivatives (1–5) in acidic solutions has been investigated both experimentally and theoretically to provide insight into the influence of some factors on the hydrolysis reaction rate. The result of this work shows that the electrogenerated p-quinoneimines participate in the hydrolysis reaction and are converted to the p-benzoquinone. The hydrolysis reaction rate strongly depends on the structure of the p-aminophenols and solution's pH. In this work, the observed homogeneous rate constants of hydrolysis (kobshyd) of p-quinoneimines were determined using digital simulation technique. The effect of different parameters such as: change of Gibbs free energy (ΔG) of the electrochemical oxidation of para-aminophenol derivatives (1–5), charge of reaction site, N–C4 bond order (Wiberg Bond Indices, WBIs) and the nature of substituted group, on the hydrolysis rate constant were also studied. All calculations were performed using Density Functional Theory (DFT) both BP86 and B3LYP levels of theory and 6-311G (p,d) basis set. The results showed that the N–C4 bond order and charge on the reaction site play significant roles in hydrolysis reaction's rate.

Some new sulfonamide derivatives were synthesized in aqueous solutions via anodic oxidation of 2,5-diethoxy-4-morpholinoaniline in the presence of arylsulfinic acids using a commercial carbon anode. In addition, the formation mechanism of the products was discussed. The obtained data show that the electrogenerated quinone diimine undergoes a Michael-type addition reaction with arylsulfinic acids to yield the respective sulfonamide derivatives. In this work, two different types of products (mono- and disulfone derivatives) in the same precursor could be isolated just by controlling the exerted potentials.

Electrochemical oxidation of some catechol and hydroquinone derivatives has been investigated both experimentally and theoretically to bring hints into the connection of thermodynamic and oxidation potential. The theoretical results were calculated at DFT (B3LYP, BP86) levels of theory and 6–311G (p,d) basis sets. In this study we focus on the mechanisms of the electrochemical oxidation of catechol in the presence of various nucleophiles. A general thermodynamic cycle, which is proposed to calculate ΔG of oxidation of the intermediates and products, introduces thermodynamic as one of the important parameters on the reaction mechanisms. The results of this work show that electrochemical oxidation potential of studied compounds is directly dependent on the ΔG of electrochemical oxidation. Also it was found that depending on the ΔG of electrochemical oxidation, the products which are produced on the surface of electrode will participate in the electrochemical or chemical following reactions. Finally we can consider several mechanisms in the electrochemical oxidation of catechol in the presence of different nucleophiles.

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