Bmim ionic liquids as media for the electrochemical oxidation of 2,6-di-t-butylphenol

Abstract

The electrochemical oxidation of the substituted phenol 2,6-di-t-butylphenol is studied at platinum electrodes using a number of 1-butyl-3-methylimidazolium (bmim) ionic liquids (BF 4 , PF 6 and N(CF 3 SO 2 ) 2 ), and compared with the oxidation obtained using a traditional solvent/electrolyte system (CH 3 OH/CH 2 Cl 2 and LiClO 4 ). The electrolysis leads to anodic coupling, resulting in the corresponding diphenoquinone, which upon reduction produces the biphenol. Best results were obtained for the conventional solvent and electrolyte, where the oxidation was found to take place via an indirect method. It was found that the ionic liquids performed better upon dilution with a suitable solvent such as acetonitrile, yielding higher conductivities due to ion separation. Dilution studies were performed with acetonitrile, methanol, dichloromethane and acetone and the resulting increase in conductivity of the ionic liquid was in the order: acetonitrile [ methanol [ acetone [ dichloromethane. This trend is in line with the dielectric constant and the dipole moment of the solvent used. It was found that the electrolysis proceeded best in the following order: conventional solvent/electrolyte [ ionic liquid suitably diluted [ ionic liquid. Among the ionic liquids, best results were obtained for [bmim] [BF 4 ]. Cyclic voltammetry data was used to further explain the electrolysis as a function of dilution.

Coexistence of Substituted Phenols Reduces the Fouling Ability of Phenol in Non-aqueous Solvents

“…There have been several publications concerning with the electrooxidation of phenols in non-aqueous systems. The majority of substituted phenols form dimers as products of their electrooxidation typically the ones having one or more tert-butyl groups [1][2][3][4] and chlorophenols [5]. Previously, we found that some para-substituted phenol give reproducible current signal in acetonitrile on platinum electrode in 50 mM concentration [6].…”

Investigation of phenol electrooxidation in aprotic non-aqueous solvents by using cyclic and normal pulse voltammetry

“…Ionic liquids provide also an appropriate medium for electrooxidation processes due to their wide potential window. Some phenols showed reversible electrochemical behaviour using ionic liquids as solvent [29,30].…”

Studies of Phenol Electrooxidation Performed on Platinum Electrode in Dimethyl Sulphoxide Medium. Determination of Unreacted Phenol by the Effect of 4‐Vinylbenzenesulphonate on the Electrooxidation Process

“…Although water is mainly in focus as solvent due to its practical interest (development of permselective layer, corrosion protection, wastewater treatment) but numerous electrochemical investigations are found in literature carried out in organic solvents. When phenol is electrochemically oxidized presenting itself in solution, an insulating poly(phenyleneoxide) film develops and some works utilized its properties [1][2][3][4][5][6][7]. However, polymers prepared from phenols are known as very weak electronic conductors, silylated poly(phenyleneoxides) have outgoing conductivity [8].…”