Effect of Electron-Donating Groups on the Electrochemical Degradation of Aromatic Nitro Compounds in Aprotic Media Containing CO₂

Abstract

The electrochemical degradation of p-nitrochlorobenzene in aprotic media containing CO2 is reported. Little is known about the effects of electron-donating groups on electrochemical degradation of aromatic nitro compounds. Accordingly, electrochemical behavior of nitrobenzene (NB), para-nitrotoluene (PNT), and para-nitroanisole (PNA), in an aprotic solvent containing CO2, was investigated by cyclic voltammetry (CV), in situ Fourier transform infrared (FT-IR) spectroscopy, and potenstiostatic electrolysis. It was established that their electrochemical reduction was an irreversible four-electron transfer process. Based on cyclic voltabsorptometry (CVA), derivative cyclic voltabsorptometry (DCVA), and chronoamperometry (CA), a mechanism of electroreduction of aromatic nitro compounds in the presence of CO2 was proposed. The products of potenstiostatic electrolysis, in the presence of CO2, were characterized by X-ray single-crystal diffraction, 13C NMR, and 1H NMR. NB and PNT gave only the corresponding azo compound with a 99% conversion rate. However, the conversion rate of PNA was lower (78%) due to the effect of the strong electron-donating methoxy group. The intermediate reduction product 4,4′-dimethoxyazoxybenzene was formed along 4,4′-dimethoxyazobenzene. In the process, CO2 was converted to CO3 2–. This constitutes a new way of carbon sequestration.

Alloying promotion of Pd-based metallenes in electrocatalytic hydrogenation of functionalized nitroarenes

“…S5, ESI †), which showed a new cathodic peak at 0.05 V vs. RHE corresponding to the stepwise reduction of nitro. 39,40 Such cathodic reduction of 4-NS before the HER conrms its thermodynamic priority, in which electrons can be used to reduce nitroarenes with chemisorbed H* or via a proton-coupled-electron transfer (PCET) process. 18,41 The reduction of 4-NS can produce 4-VA and 4-ethylnitrobenzene (4-EN) via selectively hydrogenating nitro and vinyl groups, respectively, both of which would be further reduced to 4-EA.…”

A Green and Efficient Synthesis Method of Benzo[c]cinnolines: Electrochemical Reduction of 2,2’‐Dinitrobiphenyl in the Presence of CO2

“…Jih Ru Hwu [16] investigated conversion of nitroaromatic hydrocarbons into intramolecular coupling azoxy compounds by three sequential 1,2 eliminations with sodium bis (trimethyl) amide as a deoxidizer in the proton inert solvent THF. In our group, intermolecular coupling of mononitro compound to form azonic compound have been realized during electrochemical reduction of mononitro compound in a proton inert solvent in the presence of CO 2 [17] . Inspired by these previous works, we speculate whether CO 2 can be used as a deoxidizer to electrochemically reduce DNBP to BC, as an intramolecular coupling product.…”