One-Electron Reduction of 2-Nitrotoluene, Nitrocyclopentane, and 1-Nitrobutane in Room Temperature Ionic Liquids: A Comparative Study of Butler–Volmer and Symmetric Marcus–Hush Theories Using Microdisk Electrodes

Abstract

The voltammetry for the reduction of 2-nitrotoluene at a gold microdisk electrode is reported in two ionic liquids: trihexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate ([P14,6,6,6][FAP]) and 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][NTf2]). The reduction of nitrocyclopentane (NCP) and 1-nitrobutane (BuN) was investigated using voltammetry at a gold microdisk electrode in the ionic liquid [P14,6,6,6][FAP]. Simulated voltammograms, generated through the use of Butler–Volmer theory and symmetric Marcus–Hush theory, were compared to experimental data, with both theories parametrizing the data similarly well. An experimental value for the Marcusian parameter, λ, was also determined in all cases. For the reduction of 2-nitrotoluene, this was 0.5 ± 0.1 eV in both solvents, while for NCP and BuN in [P14,6,6,6][FAP], it was 2 ± 0.1 and 5 ± 0.1 eV, respectively. This is attributed to the localization of charge on the nitro group and the primary nitro alkyl’s increased interaction with the environment, resulting in a larger reorganization energy.