Reference Electrodes for Use in Polar Aprotic Solvents

Reference Electrodes for Use in Polar Aprotic Solvents. The increased use of polar aprotic solvents for electrochemical studies has inspired a search for suitable reference electrodes. Although the description of an aprotic solvent is somewhat ambiguous (see Chapter 6), we include in this class those solvents 

TABLE 5.4 Reference Electrodes for Use in Dipolar Aprotic Solvents  

Reference Electrode Acetonitrile Propylene Carbonate Dimethyl Formamide Dimethyl Sulfoxide 

Until recently, the most popular reference half-cell for potentiometric titrations, polarography, and even kinetic studies has been the saturated aqueous calomel electrode (SCE), connected by means of a nonaqueous salt bridge (e.g., Et4NC104) to the electrolyte under study. The choice of this particular bridge electrolyte in conjunction with the SCE is not a good one because potassium perchlorate and potassium chloride have a limited solubility in many aprotic solvents. The junction is readily clogged, which leads to erratic junction potentials. For these practical reasons, a calomel or silver-silver chloride reference electrode with an aqueous lithium chloride or quaternary ammonium chloride fill solution is preferable if an aqueous electrode is used. 

Me2SO solutions platinized platinum electrodes apparently decompose the solvent by catalytic reduction. 

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