Electrochemical Behavior of Quinoxalin-2-one Derivatives at Mercury Electrodes and Its Analytical Use

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Zimpl, Milan ; Skopalova, Jana ; Jirovsky, David ; Bartak, Petr ; Navratil, Tomas ; Sedonikova, Jana ; Kotoucek, Milan (2012)
  • Publisher: The Scientific World Journal
  • Journal: The Scientific World Journal, volume 2,012 (issn: 2356-6140, eissn: 1537-744X)
  • Related identifiers: doi: 10.1100/2012/409378, pmc: PMC3361246
  • Subject: Research Article | Science (General) | Q1-390 | Article Subject

Derivatives of quinoxalin-2-one are interesting compounds with potential pharmacological activity. From this point of view, understanding of their electrochemical behavior is of great importance. In the present paper, a mechanism of electrochemical reduction of quinoxalin-2-one derivatives at mercury dropping electrode was proposed. Pyrazine ring was found to be the main electroactive center undergoing a pH-dependent two-electron reduction process. The molecule protonization of nitrogen in the position 4 precedes the electron acceptance forming a semiquinone radical intermediate which is relatively stable in acidic solutions. Its further reduction is manifested by separated current signal. A positive mesomeric effect of the nonprotonized amino group in the position 7 of the derivative III accelerates the semiquinone reduction yielding a single current wave. The suggested reaction mechanism was verified by means of direct current polarography, differential pulse, cyclic and elimination voltammetry, and coulometry with subsequent GC/MS analysis. The understanding of the mechanism was applied in developing of analytical method for the determination of the studied compounds.
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