The Preparation Of PTFE Modified Electrodes And Their Application In Electrosynthesis Of Aromatic Organics

Aromatic organic compounds are common chemical raw materials and reagents, and the preparation methods of these aromatic organic compounds were utilizing the traditional chemical synthesis which usually had been some serious problems of long synthesis steps, low rate of transformation, high production cost, severe pollution of enviroment and so on. However, electrochemical synthesis only involves in electronic gain and loss, it will be the pioneer of "green chemistry" and the new hotspot in the research of organic synthesis.Based on the excellent hydrophobicity and corrosion resistance of polytetrafluoroethylene (PTFE), three PTFE modified coatings were prepared by composite electroplating, then the optimum preparation conditions were explored and the surface morphology, composition and properties of three coatings were measured. Three PTFE modified coatings as electrodes were applied to the electrochemical synthesis of aromatic organic compounds, the electrosynthesis of salicylaldehyde,3,4,5-trihydroxybenzaldehyde, salicylic alcohol, vanillyl alcohol and benzoic acid were achieved, respectively. The electrochemical parameters such as cyclic voltammetry, Tafel polarization curve and electrochemical impedance spectroscopy of three PTFE modified electrodes in aromatic organic electrolytes were measured, and the conversion rate and current efficiency of these reactions were studied. These electrosynthesis products were characterized eventually.The experimental results showed that three PTFE modified electrodes possessed a higher catalytic activity and corrosion resistance than that of pure metal electrodes in aromatic organic electrolytes. The conversion rate of the electroreduction of salicylic acid and gallic acid on Cu-PTFE modified electrode were 85.47% and 72.18%, respectively. The conversion rate of electroreduction of salicylaldehyde on Cu-PTFE and Ni-PTFE modified electrodes were 80.36% and 75.56%, respectively. The conversion rate of electroreduction of vanillin on Cu-PTFE and Ni-PTFE modified electrodes were 83.23% and 86.92%, respectively. The conversion rate of electrooxidation of benzaldehyde on Pb-PTFE modified electrode was 89.25%. The investigation of the behavior of electrosynthesis reaction kinetics suggested that the electroreduction of salicylic acid, vanillin and the electrooxidation of benzaldehyde on PTFE modified electrodes would be controlled mainly by electron transfer process. And the electroreduction of gallic acid and salicyladehyde would be controlled by both electron transfer process and concentration diffusion process. In addition, the electrochemical impedance data were fitted through ZSimpWin software and the equivalent circuits was used for simulating the electrochemical properties of these electrode/solution interfaces.