Electrochemistry in tetrahydrofuran and at low temperature: protocol, procedures and methods

摘要

This review describes the protocol, procedures and methods for electrochemical studies in THF and at lowtemperature that have been developed in the course of the last 5 years in our laboratory. Electrochemical studiesin THF benefit from a large accessible potential window. In practice, it is however necessary to avoid the presence ofhumidity in the electrochemical cell. A specific reference electrode had to be designed for those measurements.Microelectrodes, the voltammetric response of which is negligibly affected by the resistivity of the medium, werepreferred to macroelectrodes. Moreover, a methodology has been developed for the quantitative analysis of bothvoltammetric and chronoamperometric curves obtained for the microelectrodes. The fitting of chronoamperometricmeasurements using the Shoup and Szabo's expression allows us to estimate the diffusion coefficient of the substrate.The modelling of the cyclic voltammograms measured over a large range of scan rates allows the confirmation of thediffusion coefficient of the substrate D_A,the determination of diffusion coefficient the electrogeneratedmolecule D_B,of the formal potential E~0_f,transfer coefficient a and of the standard heterogeneous rate constantfor the electron transfer K_o. Typically, systems are investigated at temperatures ranging from room temperature to192 K. Parameters obtained at various temperatures are used to extract, through Arrhenius plots, the activationenergies both for the diffusion coefficient E_A(D) and for the electron transfer reactionEA(ko)