Exploring the Use of Hypervalent Iodine Complexes to Aid in the Electrochemical Detection of Hydroquinones and Phenolic Compounds

Abstract:

Exposure to environmental hydroquinones and phenols that are used in certain industrial processes can cause detrimental effects to humans and animals if not disposed properly. It can be difficult to continuously detect these compounds, which makes it hard to safely dispose of them. Electrochemical detection of phenol is attractive due to its high sensitivity and potentially high selectivity. Unfortunately, the electrochemical oxidation of phenols is known to foul electrodes, thereby prohibiting continuous monitoring.
To avoid electrode fouling, this project focused on a preliminary proof of concept method to detect hydroquinones and phenols by using a hypervalent iodine complex to initially chemically oxidize the analyte of interest, which then can be detected by electrochemically reducing the resulting product. Hydroquinone was initially used as a model compound that readily oxidizes to its benzoquinone substituent through the iodine complex and can be detected when its reduced electrochemically. Additionally, the iodine complex used is an environmentally safe molecule that breaks down overtime i1nto its iodonium salts.
This presentation will investigate the mechanism involved in oxidizing hydroquinone and phenol, as well as other similar compounds such as catechol and resorcinol. This will involve FTIR, NMR, and electrochemical methods. Optimized reaction conditions will be presented to give the best results for the oxidation of the analyte and produce consistently accurate data upon electrochemical reduction. The reductions were preformed using a glassy carbon electrode in a pH 2.8 buffer with 1M KCl. This allows easy proton transfer during the reduction of the species in question.