Abstract
Abstract Electrochemical behaviour of Chocolate Brown HT azo dye has been exhaustively studied at a glassy carbon electrode in Britton-Robinson buffers differing in pH values from 2 to 12 using repetitive cyclic voltammetry to investigate both electrochemical pathways and predict the most likely reaction products. This study has confirmed and deepened recently discovered insights into the electrochemical properties of di-azo dyes, which indicate a two-stage electron-transfer–electron-transfer–chemical reaction (EEC) mechanism in the cathodic reduction pathway and an electron-transfer–chemical reaction–chemical reaction (ECC) mechanism in the anodic oxidation pathway. Both pathways lead to the breakdown of the Chocolate Brown HT molecule through cleavage of both azo groups, yielding two molecules of 4-aminonaphthalene-1-sulphonate and one molecule of 2,4-diamino-1,3-dihydroxy-5-hydroxymethylbenzene as the most likely electrochemical reduction products. Conversely, two molecules of 4-nitrosonaphthalene-1-sulphonate and one molecule of a 1,2-benzoquinone imine derivative represent the most likely electrochemical oxidation products. Finally, an assessment of the potential analytical implications of these findings from the molecular electrochemistry of Chocolate Brown HT is included as well. Graphical abstract