Electrochemical and spectroscopic study of 2-iodobenzoic acid and 2-iodosobenzoic acid anodic oxidation in aqueous environment

Abstract

2-iodosobenzoic acid and especially IBX represent interesting selective and green hypervalent iodine oxidants. Mainly due to issues connected with their preparation, use of these compounds is limited to laboratory scale. From this point of view, the electrochemical synthesis represents interesting platform for inherently safer production of these highly valued oxidants. In order to provoke and allow more intense investigation in this direction, this work aimed to present basic aspects of electrochemical behaviour of these compounds in aqueous environment using several anode materials. A combination of various experimental approaches in combination with time-dependent density functional theory calculations allowed determining compounds speciation in a wide range of pH values. The most interesting in this sense is iodoxol ring opening after/during deprotonation of 2-iodosobenzoic acid to 2-iodosobenzoate. This process is accompanied by addition of water molecule to the iodine atom. Using voltammetry and controlled potential preparative batch electrolysis allowed constructing approximate form of Pourbaix diagram of the investigated compounds. Finally, diffusion coefficients of investigated compounds and anodic charge transfer coefficients of oxidation reactions were determined based on detailed analysis of linear voltammograms. The results provide a solid base for further investigation of electrochemical synthesis of 2-iodosobenzoic acid and IBX in aqueous environment.