3，6-二氯吡啶甲酸的电解合成方法 毕业论文.rar

3,6-二氯吡啶甲酸的电解合成方法 毕业论文

摘  要
全卤吡啶脱氯是卤代吡啶类化合物合成的新尝试， 本文在国内外卤代吡啶合成研究的基础上，选择了以电化学还原作为研究方向，以3,4,5,6-四氯吡啶甲酸、五氯吡啶、3,4,5,6-四氯-2-三氯甲基吡啶为原料，主要研究了其在银和碳载银电极上的还原行为。
本文第一章具体论述了三种原料脱氯后的目标产物的性质、用途及制备方法，电极材料的应用等。为本实验提供了研究背景。
第二章主要讲述了本文所涉及的实验内容和方法。
第三章主要研究了3,4,5,6-四氯-2-三氯甲基吡啶在银电极上的电还原行为。采用循环伏安法，计时电量法和恒电位电解法等电化学测试手段对3,4,5,6-四氯-2-三氯甲基吡啶的阴极还原行为，动力学特征及反应历程进行了详细的研究。
结果表明：银电极对3,4,5,6-四氯-2-三氯甲基吡啶的电还原脱氯具有很高的电催化活性；3,4,5,6-四氯-2-三氯甲基吡啶在银电极上的还原是由扩散所控制的电化学-化学过程；3,4,5,6-四氯-2-三氯甲基吡啶在纯乙腈、乙腈/水混合溶液、N,N-二甲基甲酰胺、乙醇中都能被还原；恒电位电解实验表明还原产物主要为脱氯加氢的产物，低电位时副产物较少，其中含水溶剂中可主要生成目标产物3,4,5,6-四氯-2-二氯甲基吡啶，副产物较少，纯乙腈溶液中副反应较多；通过计时电量法求得3,4,5,6-四氯-2-三氯甲基吡啶在乙腈:水=5:1的混合溶剂中的扩散系数为D=2.7×10-5 cm2/s。
第四章主要研究了碳载银的制备及其电催化性能。分析了不同功能离子预吸附、银离子浓度等因素对碳载银制备的影响；将碳载银制成粉末微电极，采用循环伏安法测试其对3,4,5,6-四氯吡啶甲酸、五氯吡啶、3,4,5,6-四氯-2-三氯甲基吡啶的电催化性能。
结果表明：利用功能离子预吸附的方法能有效将银分散在碳粉上，功能离子预吸附后分散效果及载银量均好于直接吸附，功能离子分散能力大小顺序为：Cl-﹤Br-﹤I-；银离子浓度并非越高效果越好， 50~500mg/L催化效果随银离子浓度升高而增大，在1000mg/L时催化效果下降；碳载银电极的电化学测试结果表明其对3,4,5,6-四氯吡啶甲酸、五氯吡啶、七氯吡啶的脱氯还原中电化学步骤相对其他步骤较快，有催化作用，且银的粒径越小，催化效果越好；
关键词：3,4,5,6-四氯吡啶甲酸，五氯吡啶，3,4,5,6-四氯-2-三氯甲基吡啶，银电极，碳载银电极

Abstract
Dechlorination of entire halide pyridines pyridine is a new attempt for halogenated pyridines synthesized. Based on the research and development of synthesis of halogenated pyridines the paper chose the electrochemical reduction as a research direction, and to 3,4,5,6–tetrachloropicolinic acid, pentachloropyridine, 3,4,5,6-tetrachloro-2-trichloromethylpyridine for raw materials, the reduction behavior on  silver and carbon -containing silver electrode was mainly studied.
    ChapterI discussed the character, use and synthesis of 3,6–dichloropicolinic acid, 2,3,4,5-tetrachloropyridine, 3,4,5,6-tetrachloro-2-dichloromethylpyridine which were production of dechlorination of the three raw materials, the electrode materials applications were also disscussed. Provide background for the research.
Chapter II focuses on the experiment contents and methods.
In chapter III, electrochemical reduction behavior of 3,4,5,6-tetrachloro-2-trichloromethylpyridine on silver electrode was disscussed. The cathodic reduction behavior, the reaction kinetics and course of 3,4,5,6-tetrachloro-2-trichloromethylpyridine were carried out a detailed study by cyclic voltammetry, chronocoulometry and potential-controlled electrolysis.
The results showed that: silver electrode had a high electro-catalytic activity to 3,4,5,6-tetrachloro-2-trichloromethylpyridine; the reduction of 3,4,5,6-tetrachloro-2-trichloromethylpyridine on silver electrode was a diffusion-controlled irreversible process; the process was an EC (electrochemistry-chemistry) process; 3,4,5,6-tetrachloro-2-trichloromethylpyridine in pure acetonitrile, acetonitrile / water mixture solution, N, N-dimethylformamide, ethanol can be reduct; Potential-controlled electrolysis experiments showed that the main product were dechlorination and hydrogenation products, less byproducts had been produced at low potential; The byproducts can be reduced in the solvent containing water. The diffusion coefficient of 3,4,5,6-tetrachloro-2-trichloro methylpyridine in the mixed solvent which were acetonitrile: water = 5:1 was find out by chronocoulometry. D = 2.7 × 10-5 cm2 / s.
The major studies of Chapter IV were preparation methods of carbon containing silver, and its catalytic properties. It was analyzed that the effection on the preparation of carbon contained silver of different function ions of pre-adsorption, and silver ion concentration; and it was made of powder microelectrode testing electro-catalytic properties of 3,4,5,6-tetrachloropicolinic acid, pentachloropyridine, 3,4,5,6- tetrachloro-2-trichloromethylpyridine by cyclic voltammetry.
The results show that: use of functional ions pre-adsorption method can be effectively dispersed the silver, the order of decentralized capacity of functional ions: Cl-<Br- <I-; The concentration of silver ion is not the higher the better, and when the concentration were 50~500mg/L, catalytic effect increase with silver ion concentration increased but reduced at 1000mg/L. Carbon containing silver electrode electrochemical test results demonstrate that in the dechlorination of 3,4,5,6– tetrachloropicolinic acid, pentachloropyridine, 3,4,5,6- tetrachloro-2-trichloro methylpyridine, electrochemical reduction steps were faster than other steps, and the smaller the particle size of silver, better catalytic effect.
key words: silver electrode, carbon contain silver electrode, 3,4,5,6–tetrachloropicolinic acid, pentachloropyridine, 3,4,5,6-tetrachloro-2-trichloromethylpyridine,