The Effect Of Proton Receptors On The Electrochemical Oxidation Behavior Of 2,4,6-tri-tert-butylphenol And Proton Donors On The Electrochemical Reduction Behavior Of 3,5-di-butyl-1,2-benzoquinone

In this paper,we systematically investigate the effect of different proton receptors and proton donors on the electrochemical behavior of 2,4,6-tri-tert-butylphenol(TTBP)and 3,5-di-butyl-1,2-benzoquinone,mainly explain the experimental phenomenas from the aspects of pH effects.Cyclic voltammetry was used to study the effect of low concentration of PBS buffer solution and triethanolamine-HCl buffer solution on the electrochemical behavior of TTBP,we observed that low buffering capacity could cause the generation of new oxidation peak,and the peak current of the new oxidation peak is proportional to the concentration of the proton receptor,which has nothing to do with the concentration of the TTBP.We changed the pH and the kind of buffer solution,found that the emergence of the new oxidation peak was not because TTBP and proton receptor forming new compounds,but due to the sudden change of pH on electrode interface.Cyclic voltammograms are often referred to as electrochemical spectrum for mechanism research.When there is a new voltammetric peak appeares,we think new material generate and combine with other results to infer redox reaction mechanism.Our results show that the pH effect complicates the cyclic voltammograms,they are no longer simply reflect the electrochemical properties of electroactive material,our work has find out the cause of the new voltampere,for our further study the mechanism of the PCET reactions in the absence of buffer and in non-aqueous media is meaningful.In this article,using dry acetonitrile as the solvent,add different intensity proton donor to 3,5-di-butyl-1,2-benzoquinone,through the experiments we found that the addition of proton donor can make the first reduction peak of 3,5-di-butyl-1,2-benzoquinone gradually disappears,we infer that this is because when 3,5-di-butyl-1,2-benzoquinone reducts in acetonitrile,it's bivalent anions get two protons and form corresponding phenol,and because the proton donor inhibits the increase of pH on electrode surface,a new peak appears at the positive potential side of the first reduction peak,the position of the new peak depends on the strength of the acid,the stronger the acidity is,the more positive the position of the new peak is.By the experimental phenomena,we may safely draw the conclusion:the electrochemical behavior of 3,5-di-butyl-1,2-benzoquinone in aprotic solvents much affected by the proton donor.The height of newly generated reduction peak depends on the concentration of the proton donor,in addition,the potential of the new reduction peak depends on the size of the proton donor's pKa values,the smaller the pKa value is,the more positive the position of the new peak is.In aprotic solvents,the electrochemical reduction of 3,5-di-butyl-1,2-benzoquinone is greatly influenced by the pH on electrode surface,therefore,we infer that the reduction rate of 3,5-di-butyl-1,2-benzoquinone in aprotic solvents relates to the pH value on the electrode surface.