Investigating Comproportionation in Multielectron Transfers via UV–Visible Spectroelectrochemistry: The Electroreduction of Anthraquinone-2-sulfonate in Aqueous Media

• Published in: Analytical chemistry (Washington) Vol. 94; no. 35; pp. 12152 - 12158
• Main Authors: Romay, Luis, González, Joaquín, Molina, Ángela, Laborda, Eduardo
• Format: Journal Article
• Language: English
• Published: Washington American Chemical Society 06-09-2022
• Subjects: Analytical chemistry; Anthraquinone; Anthraquinones; Aqueous solutions; Cations; Chemistry; Diffusion layers; Kinetics; Light beams; Mass transport; Quantitative analysis; Signal processing; Sulfonates
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.2c02523

UV–vis spectroelectrochemistry is assessed as a tool for the diagnosis and quantitative in situ investigation of the incidence of comproportionation in multielectron transfer processes. Thus, the sensitivity of the limiting current chronoabsorptometric signals related to the different redox states to the comproportionation kinetics is studied theoretically for different working modes (normal and parallel light beam arrangements) and mass transport regimes (from semi-infinite to thin layer diffusion). The theoretical results are applied to the spectroelectrochemical study of the two-electron reduction of the anthraquinone-2-sulfonate in alkaline aqueous solution, tuning the thermodynamic favorability of the comproportionation reaction through the electrolyte cation. The quantitative analysis of the experimental results reveals the occurrence of comproportionation in the three media examined, showing different kinetics depending on the cationic species in solution.