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纳米镍钴的制备及其应用于酮酸酯电催化不对称加氢的研究

发布时间:2019-01-03 15:57  文章来源:笔耕文化传播
【摘要】:不对称催化合成作为制备手性化合物的一种重要手段,已经得到越来越多科研工作者的关注,并且取得了众多的科研成果。其中,催化剂作为不对称催化合成反应的重要反应媒介,尤其受到人们的重视,金属催化剂是其中重要的一类。大多数不对称金属催化剂均为Pt、Pd等铂族贵金属,然而这类贵金属的全球储量有限,并且还在贵重饰品、高新材料等领域有着重大需求。因此,开发非贵金属不对称催化剂有着重要的研究价值。电化学合成作为一门绿色合成技术有着众多优点,逐渐得到人们的青睐,特别是已经出现了一些利用电化学方法制备手性化合物的科学研究。本论文主要从上面两点出发,研究非贵金属Ni、Co纳米材料的制备及其应用于酮酸酯类化合物电催化不对称加氢的效果。具体实验研究如下:(1)纳米镍的制备及其应用于酮酸酯电催化不对称加氢的研究利用液相化学还原法制备纳米镍材料,用XRD、SEM等方法表征合成的纳米镍,并将其压成圆片以作工作电极。在一室型电解池中,以制备的纳米镍为工作电极,分别以生物碱和酒石酸为手性诱导剂,H2O为氢源,研究纳米镍电催化苯甲酰甲酸乙酯和苯甲酰乙酸乙酯两种酮酸酯不对称加氢的效果。分别用GC-MS对产物定性分析,HPLC对产物进行定量分析。考察了电解电量,溶剂配比,电流密度,反应温度等对反应的影响;并考察了两底物在纳米镍电极上的循环伏安行为。实验结果证明纳米镍应用于羰基化合物电催化不对称加氢的思路行之有效。(2)TA@Ni/Co手性双金属纳米材料的制备及其应用于α酮酸酯电催化不对称加氢的研究在制备纳米镍材料的基础上,将相应的液相还原条件加以改进,以Ni盐和Co盐摩尔比为1:1制备Ni/Co纳米双金属,再利用酒石酸和Ni、Co等金属较强的相互作用,将手性酒石酸修饰到Ni/Co纳米材料中,制备出TA@Ni/Co手性双金属纳米材料。用XRD、SEM、ICP、FT-IR等方法表征合成的材料。将TA@Ni/Co手性双金属纳米材料修饰于碳纸表面,作工作电极。在一室型电解池中,以醇类为氢源,研究手性双金属纳米材料电催化苯甲酰甲酸乙酯和苯甲酰甲酸甲酯两种α酮酸酯不对称加氢合成的效果。同样考察了苯甲酰甲酸乙酯在手性双金属电极上的循环伏安行为。实验结果显示,以TA@Ni/Co手性纳米双金属为工作电极相较于以单金属纳米镍为工作电极,电解产物在保有一定ee值的基础上,产率提升相当高。
[Abstract]:Asymmetric catalytic synthesis as an important method for the preparation of chiral compounds has been paid more and more attention by researchers and many scientific achievements have been obtained. As an important reaction medium of asymmetric catalytic synthesis, catalysts have been paid more and more attention, among which metal catalysts are one of the most important ones. Most asymmetric metal catalysts are platinum group precious metals such as Pt,Pd. However, the global reserves of these precious metals are limited, and there is a great demand in such fields as precious ornaments, high-tech materials and so on. Therefore, the development of non-noble metal asymmetric catalysts has important research value. Electrochemical synthesis as a green synthesis technology has many advantages, and has been gradually favored by people. Especially, there have been some scientific research on the preparation of chiral compounds by electrochemical methods. In this paper, the preparation of non-precious metal Ni,Co nanomaterials and its application in asymmetric hydrogenation of ketoacid esters were studied from the above two points. The experimental results are as follows: (1) preparation of nano-nickel and its application in asymmetric hydrogenation of ketoate; Nano-nickel was prepared by liquid-phase chemical reduction method and characterized by XRD,SEM method. It is pressed into a disk to serve as a working electrode. In a one-chamber electrolytic cell, the prepared nano-nickel was used as working electrode, alkaloids and tartaric acid as chiral inducers and H2O as hydrogen source, respectively. The asymmetric hydrogenation of ethyl benzoyl formate and ethyl benzoyl acetate catalyzed by nanometer nickel was studied. GC-MS and HPLC were used for qualitative analysis and quantitative analysis respectively. The effects of electrolysis, solvent ratio, current density and reaction temperature on the reaction were investigated, and the cyclic voltammetry of the two substrates on the nanocrystalline nickel electrode was investigated. The experimental results show that the application of nano-nickel in asymmetric hydrogenation of carbonyl compounds is effective. (2) preparation of TA@Ni/Co chiral bimetallic nanomaterials and their application in asymmetric hydrogenation of 伪 ketoate Based on the preparation of nanocrystalline nickel, The corresponding liquid phase reduction conditions were improved to prepare Ni/Co nano-bimetallic at 1:1 with the molar ratio of Ni salt and Co salt as 1:1. The strong interaction between tartaric acid and Ni,Co and other metals was used. Chiral tartaric acid was modified into Ni/Co nanomaterials to prepare TA@Ni/Co chiral bimetallic nanomaterials. The synthesized materials were characterized by XRD,SEM,ICP,FT-IR and other methods. TA@Ni/Co chiral bimetallic nanomaterials were modified on the surface of carbon paper and used as working electrode. The asymmetric hydrogenation of ethyl benzoate and methyl benzoate was studied in a one-chamber electrolytic cell using alcohol as hydrogen source and chiral bimetallic nanomaterials as catalyst. The cyclic voltammetry of ethyl benzoate on chiral bimetallic electrode was also investigated. The experimental results show that the yield of electrolysis products with TA@Ni/Co chiral nanometer bimetallic as working electrode is higher than that with single metal nanocrystalline nickel on the basis of keeping a certain ee value.
【学位授予单位】:华东师范大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:O621.251

【参考文献】

相关期刊论文 前2条

1 傅小明;;纳米镍的物理法制备技术及研究现状[J];湖南有色金属;2010年03期

2 许锡恩,王志峰,,田松江;手性金属络合物催化剂的制备和应用[J];石油化工;1996年02期



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