Electrochemical\nInvestigation of the Oxidation of\nPhenolic Compounds Using Hypervalent Iodine Oxidants

The chemical oxidation of simple phenolic compounds by\nthe hypervalent\niodine reagent [hydroxy(tosyloxy)iodo]benzene (HTIB) was investigated\nusing electrochemical and spectroscopic methods. HTIB oxidized phenol\nand benzenediol isomers hydroquinone (HQ), catechol, and resorcinol\nto form various quinone structures. HQ and catechol, two compounds\nthat show reversible electrochemical behavior, exhibited simple oxidative\nchemistry to their respective quinone structures that could be electrochemically\nreduced at a glassy carbon electrode. An HTIB:compound ratio of 2:1\nresulted in the complete chemical oxidation of these model compounds.\nHowever, phenol and resorcinol, two compounds that are known to readily\nfoul electrode surfaces upon their electrochemical oxidation, required\na 6:1 HTIB:compound ratio to achieve complete chemical oxidation.\nThe oxidation of resorcinol resulted in a compound that could not\nbe electrochemically reduced; however, the oxidation of phenol from\nHTIB resulted in an electrochemical redox couple that suggested the\npreferential formation of benzoquinone, with the possibility of some <i>o</i>-quinone also being produced. This work serves as a proof-of-concept\nmethod for the possible indirect electrochemical detection of phenolic\ncompounds.