The mechanism of electrochemical oxidation of p-phenylenediamine and 4-aminophenol in the presence of malononitrile, as a nucleophile is studied in a phosphate buffer solution (0.15M) mixed with ethanol (v:v) using the cyclic voltammetry, controlled-potential coulometry and UV-spectroscopy methods. The results obtained indicate that the oxidation form of p-phenylenediamine and 4-aminophenol participate in the 1,4-michael addition reactions with malononitrile via the ECECCC mechanism (E: electrochemical and C: chemical) for the electrochemical synthesis of new indole derivatives with good yield under controlled potential conditions. The products obtained were characterized after purification by the FT-IR, 1 H NMR, 13 C NMR, mass spectroscopy and elemental analysis.
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