Cryo-electrochemistry in tetrahydrofuran:: The electrochemical reduction of a phenyl thioether:: [(3-{[trans-4-(methoxymethoxy)cyclohexyl]oxy}propyl)thio]benzene

Cryo-electrochemistry in tetrahydrofuran (THF) with cyclic voltammetry and microdisc chronoamperometry has been applied to the reductive cleavage of the phenyl thioether: [(3-{[trans-4-(methoxymethoxy)cyclohexyl]oxy}propyl)thio]benzene, (RSPh) and has allowed the number of electrons participating in the reaction to be deduced from potential step experiments. Characteristic cyclic voltammograms and microdisc chronoamperometric experiments have been used to identify the products of the electrochemical reduction as trans-1-(methoxymethoxy)-4-propoxycyclohexane, (RH) and thiophenolate, (PhS-) which upon oxidation, rapidly dimerises to form diphenyl disulfide, (PhSSPh). In addition, preparative electrolysis confirms the proposed mechanism of reduction of RSPh as being a simultaneous two-electron reduction to give the products: trans-1-(methoxymethoxy)-4-propoxycyclohexane, (RH) and thiophenolate, (PhS-). Both chronoamperometric and voltammetric analyses performed at low temperature proved significantly advantageous over room temperature analyses. In particular, voltammetric waves and peaks were better resolved from the solvent window allowing accurate step potentials to well-defined steady-state plateaus used in chronoamperometric experiments, with voltammetric potential sweeps reversed without significant scanning into the solvent decomposition window. (c) 2006 Elsevier B.V. All rights reserved.