高分散型氮杂环卡宾钯催化剂（NHC-Pd）的制备及其对Suzuki-Miyaura反应的催化作用

发布时间：2018-05-30 18:33

本文选题：Suzuki-Miyaura偶联反应 + 高分散性　；参考：《华侨大学》2017年硕士论文

【摘要】：Suzuki-Miyaura偶联反应自从被铃木章发现以来,已经发展成构成C-C键主要方式之一,钯催化剂是Suzuki-Miyaura偶联反应中最为常见的一种催化剂。虽然磷配体的结构不断发展,已增加催化剂的活性,但是大位阻的N-杂环卡宾(NHC)配体,以其优越的稳定性和广泛的适应性,得到了广泛的关注。但是,由于大位阻NHC配体的结构特点,导致其在反应体系的中分散性降低,进而导致催化效率降低,而且大多数钯催化剂对氯代芳烃没有很好的催化活性。因此,本课题组通过在N-杂环卡宾配体上修饰具有良好柔性的长链烷氧基,制备出了一种分散性能很好的NHC-Pd(acac)Cl催化剂,并对其在Suzuki-Miyaura反应的催化性能进行了研究。本文主要研究内容如下:(1)合成了一种长链烷氧基修饰的N-杂环NHC-Pd(acac)Cl催化剂,其钯含量达到0.94 mmol/g,而且具有较好的分散性。(2)本文分别研究了催化剂对溴苯底物和氯苯底物的Suzuki-Miyaura偶联反应的最佳催化条件,发现对于溴苯底物在采用1:1乙醇/水溶剂条件下,K2CO3作为碱,50oC反应2 h即可达到反应完全;对于氯苯底物在采用异丙醇溶剂条件下,KOtBu作为碱,80oC反应8 h即可达到反应完全。而且催化剂对于溴苯底物可以达到9.1×107的TON值。(3)对催化剂的底物适应性进行了研究,发现在溴代芳烃、氯代芳烃和芳基硼酸的偶联反应中,催化剂都表现出了较高的活性和稳定性,对芳基卤化物都具有较好的底物适应性,而且反应条件更加温和,特别是对氯代芳烃的催化效果有了很大的提高。
[Abstract]:Since the discovery of Suzuki Suzuki the Suzuki-Miyaura coupling reaction has been developed into one of the main forms of C-C bond. Palladium catalyst is the most common catalyst in the Suzuki-Miyaura coupling reaction. Although the structure of phosphorus ligands has been developing continuously, the activity of catalysts has been increased, but the large steric hindrance of N-heterocyclic carbene NHCs has attracted wide attention due to their superior stability and wide adaptability. However, due to the structural characteristics of NHC ligands with large steric resistance, the dispersion of the ligands in the reaction system was decreased, and the catalytic efficiency was decreased, and most palladium catalysts did not have good catalytic activity for chlorinated aromatics. Therefore, a NHC-Pd(acac)Cl catalyst with good dispersion performance was prepared by modifying the long-chain alkoxy group with good flexibility on N-heterocyclic carbene ligands, and its catalytic performance in Suzuki-Miyaura reaction was studied. A long chain alkoxy modified N- heterocyclic NHC-Pd(acac)Cl catalyst was synthesized. The palladium content is 0.94 mmol / g and has good dispersion. In this paper, the optimum catalytic conditions for the Suzuki-Miyaura coupling reaction of bromobenzene substrates with chlorobenzene substrates have been studied. It was found that the reaction of bromobenzene substrates could be complete in 2 h with K _ 2CO _ 3 as base 50oC under the condition of 1:1 ethanol / water solvent, and that the reaction of chlorobenzene substrate with KotBu as alkali-80 oC in isopropanol solvent for 8 h. Moreover, the adaptability of the catalyst to the substrate of the catalyst was studied. It was found that in the coupling reaction of brominated aromatics, chlorinated aromatics and aryl boric acid, it was found that in the coupling reaction of bromobenzenes, chlorinated aromatics and aryl boric acid, The catalysts showed higher activity and stability, better substrate adaptability to aryl halides, and more mild reaction conditions, especially for chlorinated aromatics.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O621.251

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