The Role Of Proton Donor And Acceptor In Aprotic Solvent

Water and oxygen are the significant sources of all kind life forms. Both of them are closely related to humans’life and manufacture. On one hand, water often remains as one of the most common contaminants in the organic solvents. And on the other hand, the electrochemical reduction of oxygen is involved in fuel cell systems and in metal-air batteries. And it is also one of the important parts in the respiratory chain. Thus, the determination of water content in aprotic solvents and the study of oxygen electrochemical reduction in aprotic solvents are of great significance.The work of this paper is using Cyclic Voltammetry, on one hand, to established a new method for determining the water content of aprotic solvents by utilizing the relationship between hydroquinone (proton donor) and water (proton acceptor) in nonaqueous solvents, which slow down the pH change near the electrode surface, and on the other hand, to study the effect of pH change near the electrode surface on oxygen reduction in aprotic solvents.The first section of this paper describes the purposes and meanings of this work, and the related research progress. The second section is the establishment of a new method for determining water in aprotic solvents, acetonitrile and DMF were chosen as the solvents in this work. We found that in the process of hydroquinone oxidation, water acted as proton acceptor, which dramatically inhibited the pH decrease near the electrode surface. And as a result, the redox peak potential of hydroquinone shifted to more negative potential. The linear relationship between log10 [H2O] and AE made it possible to determine water content in aprotic solvents. This is an environmental friendly method with the advantages of lower detection limit and wide detection range. It is also easy, cheap and of high sensitivity. The third section investigated oxygen electrochemical reduction in aprotic solvent under the acidic condition and alkaline condition, respectively. And the discipline between pH and oxygen reduction was summarized. The last part is general conclusions about the experiment and the directions of future work.