五氯吡啶电合成制备2，3，5，6-四氯吡啶及电化学特性的研究.pdf

浙江I业大学硕士学位论文五氯吡啶电合成制备2,3,5,6-I匹I氯吡啶及其电化学特性研究摘要本文在国内外2,3,5,6一四氯吡啶合成研究进展的基础上,选择了以电化学还原五氯吡啶作为研究方向,主要研究了各还原体系中阴极还原行为、动力学特征及反应历程。在此基础上,利用自行设计的电解系统进行了电合成试验,并对合成工艺进行了优化。首先采用X射线(Ⅺ①)、原子力显微镜(AFM)考察了各种制备条件下银电极的表面相组成和表面形貌等特征。其次采用循环伏安法、恒电位阶跃法、稳态极化曲线法、快速电位扫描法和电解法等电化学测试手段测定了银电极的比表面积和电催化活性,对五氯吡啶的阴极电还原、动力学特征及反应历程进行了详细的研究。结果表明:电化学氧化还原(ORC)法制备得到具有纳米尺寸结构表面的粗糙化银电极具有很高的电催化活性。在各个体系下粗糙化银电极都能电催化还原五氯吡啶。在乙腈水溶液中五氯吡啶阴极还原的主要产物为2,3,5,;在纯有机体系下,五氯吡啶可以逐步电还原脱氯,最终得到吡啶。在两种体系下,有着不同的反应历程。通过实验室规模对2,3,5,, 得出了比较理想的合成工艺。在含10~15 wt%水的乙腈溶液中,使用锯齿菱形网状的粗糙化银电极作为阴极,电流密度为45 ma/cm2,反应温度为35℃,五氯吡啶电化学合成2,3,5,6一四氯吡啶收率可以达到浙江I业大学磺士学位论文 90%以上。本文的研究工作表明:五氯吡啶电化学合成2,3,5,6-四氯吡啶具有工艺流程短,产品收率高,环境污染小等优点,具有良好的经济效益和社会价值,可望在工业化生产上得到应用。关键词:2,3,5,6一四氯吡啶,电化学合成,粗糙化银电极,五氯吡啶,动力学特性强江I监大学碗士学位论文 STUDY ON ELECTROSYNTHESIS OF 2,3,5,6-TETRA -CHLOROPYRIDINE FROM PENTA CHLOR0pYRIDINE AND ITSELECTROCHEMICAL CHAR ACTERISTICS Based 011theresearch anddevelopment ofsynthesis of2,3,5,6-tetra —chloropyridine,the studies on electroreduction ofpentachloropyridine to the corresponding 2,3,5,6-tetrachloropyridine were selected and the cathodic reduction behaviours,ic characteristics and reaction mechanism were investigated ,the suitable parameters ofelectrosythesis process were evaluated by thedivided cell system. Atfirst,the surfacecrystalphase,surface morphology andspecific surface area ofroughened silverelectrodeswere characterized byusing X-ray diffraction(XRD),Atomic forceMicroscopy(AFM)and single potential step ,the catalytic activity of roughened silverelectrodesandtheelectroreduction behaviours,ic characteristicsand reaction mechanisms ofpentachloropyridine were studied indetailby electrochemical measurements such as cycle voltammetry,chronoamperometry,fast linearpotential sweep method, quasi-steady-statepolarzition andelectrolysis. 巍江I避大学硬士学位论文 The resultsshowed thattheroughened silverelectrodes which were formed byelectrochemistry oxidation reductioncycle(ORC)exhibited powerful elect