Study On Electrosynthesis Of 2, 3, 5, 6-tetrachloropyridine From Pentachloropyridine And Its Electrochemical Characteristics

Based on the research and development of synthesis of 2,3,5,6-tetra-chloropyridine, the studies on electroreduction of pentachloropyridine tothe corresponding 2,3,5,6-tetrachloropyridine were selected and thecathodic reduction behaviours, kinetic characteristics and reactionmechanism were investigated in this work. Furthermore, the suitableparameters of electrosythesis process were evaluated by the divided cellsystem.At first, the surface crystal phase, surface morphology and specificsurface area of roughened silver electrodes were characterized by usingX-ray diffraction(XRD), Atomic force Microscopy (AFM) and singlepotential step chronoamperometry. Next, the catalytic activity ofroughened silver electrodes and the electroreduction behaviours, kineticcharacteristics and reaction mechanisms of pentachloropyridine werestudied in detail by electrochemical measurements such as cyclevoltammetry, chronoamperometry, fast linear potential sweep method,quasi-steady-state polarzition and electrolysis. The results showed that the roughened silver electrodes which wereformed by electrochemistry oxidation reduction cycle (ORC) exhibitedpowerful electrocatalytic activity for the selective dechlorination ofpentachloropyridine to 2,3,5,6-tetrachloropyridine. pentachloropyridinecan be reduced in variety of conditions. 2,3,5,6-tetrachloropyridine is themain products of the electoreduction in a solution of acetonitrile andwater, while successfully dechlorination reaction is available inacetonitrile, and the final product is pyridine.The suitable parameters of electrochemical synthesis of 2,3,5,6-tetra-chloropyridine were obtained by laboratory scale experimentations. Theyield of 2,3,5,6-tetrachloropyridine is up to 90ï¼…if roughened silvercathode is used, temperature is 308K, and cathode current density is45mA/cm~2.The results showed that the preparation of 2,3,5,6-tetrachloro-pyridine by electrodechlorination of pentachloropyridine are promisingbecause of short process, little environment pollution and good qualityproducts.