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. 2022 Nov 4;3(4):101817.
doi: 10.1016/j.xpro.2022.101817. eCollection 2022 Dec 16.

Electrochemical reduction of nitrobenzene via redox-mediated chronoamperometry

Athanasios D Stergiou  1 , Daniel H Broadhurst  2 , Mark D Symes  3
Affiliations

Electrochemical reduction of nitrobenzene via redox-mediated chronoamperometry

Athanasios D Stergiou et al. STAR Protoc. .

Abstract

Anilines are important feedstocks for pharmaceuticals, dyes, and other materials, but traditional approaches to their syntheses usually lack selectivity and environmental sustainability. Here, we describe the selective reduction of nitrobenzene to aniline under mild conditions, using water as the ultimate source of the required protons and electrons. We describe the electrochemical cell assembly, and detail steps for electrochemical reduction followed by organic extraction and analysis of the extracts using NMR. For complete details on the use and execution of this protocol, please refer to Stergiou and Symes (2022a).

Keywords: Chemistry; Material sciences; NMR.

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Conflict of interest statement

A.D.S. and M.D.S. have filed a patent related to this work (EP22386046.1.).

Figures

None
Graphical abstract
Figure 1
Figure 1
Custom-made two-compartment electrochemical H-cell
Figure 2
Figure 2
Teflon tape used at the threading of the compartment joint to prevent leakage
Figure 3
Figure 3
Overall diagram of the components of the electrochemical reaction, with parts labeled as follows (A) Working side of the H-cell. (B) Counter side of the H-cell. (C) Sealing ring with Nafion membrane. (D) H-cell connector. (E) Teflon tape. (F) BioLogic SP-150 potentiostat. (G) Syringe needle for N2 purge. (H) Ag/AgCl reference electrode. (I) Working and counter electrodes. (J) Stirring bar.
Figure 4
Figure 4
Representation of the two-compartment cell during the mediated electrolysis of nitrobenzene
Scheme 1
Scheme 1
Overall reaction for the reduction of nitrobenzene via the use of the phosphotungstic acid redox mediator
Figure 5
Figure 5
Chronoamperometry parameters used in the reduction of nitrobenzene in the EC-Lab software
Figure 6
Figure 6
Reduction of nitrobenzene (A–C) 1H NMR spectra as follows; the nitrobenzene starting material (A), a sample of pure aniline used as a standard (B), and the spectrum of the electrocatalytic reaction medium after extraction and concentration (C). All spectra were obtained in CDCl3. Spectra B and C are essentially indistinguishable, showing clean conversion to aniline.
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