Investigation on the electrochemical degradation and mechanism of p-nitrochlorobenzene in aprotic media containing CO2

Abstract

The electrochemical behavior of p-nitrochlorobenzene (PNCB) in the aprotic solvent was investigated by cyclic voltammetry, bulk electrolysis, and in situ FT-IR spectroelectrochemistry. In the absence of CO2, the electrochemical behavior of PNCB is reversibly one-step single-electron transfer during the scan between -0.4 and -1.4 V, but with adding CO2, it is transformed into completely irreversible 4-electrons transfer process. The only electrolysis product indicating high selectivity in the presence of CO2 is confirmed as 4,4′-dichloroazobenzene (DAB) by X-ray single crystal diffraction, 13C-NMR, 1H-NMR and FTIR. In the absence of proton donor, the electrochemical degradation of PNCB at low potential is achieved, and CO2 is electrochemically converted to CO32− simultaneously. Based on cyclic voltabsorptometry (CVA) and derivative cyclic voltabsorptometry (DCVA) techniques, double potential step time-resolved IR scanning electrochemical technique (DPS TR IRSEC) was developed to illustrate the adsorption behavior of CO2 in the electrochemical reduction process. Therefore, a new electrochemical mechanism of PNCB in the presence of CO2 has been proposed based on the above results, which will be beneficial for theoretical research. The electrochemical degradation method is a promising and green chemical process for the degradation of chloronitrobenzene compounds (CNBs).