Study On The Mechanism Of The Coupling Reaction Of Aromatic Compounds Catalyzed By Transition Metals

In the field of drug synthesis,polymer materials,and functional materials,coupled aromatic compounds occupy an important position.In recent years,studies on the synthesis of these kinds of compounds have also become more mature,and many simple and effective methods have been found.Among them,the preparation method which uses a transition metal to catalyze the coupling reaction of aromatic compounds shows a great advantage,and its high-efficiency selectivity is far superior.Therefore,the research of these methods has higher value.However,the reaction mechanism of these types of reaction are seldom reported.It results in the limitations of these types of reaction on the choices of substrates and catalysts.Therefore,based on the presumptions of the previous scholars,the authors discuss in depth the mechanisms of the two specific reactions from the perspective of computational chemistry.The research contents and main conclusions are as follows:(1)The Density Functional Theory was used to analyze the microscopic mechanism of Cu-catalyzed self-coupling reaction of N-methyl indole coupling reaction at the basis set level of all-electronic group of B3LYP-DGDVP.All compound structures in the route were optimized and vibration analysis was performed at the same level.Combining the calculated results with the experimental characterization results,the correctness of the reaction mechanism was verified and the relevant conclusion was drawn:The CuCl-catalyzed N-methyl hydrazine coupling reaction is a free radical coupling process,and the generation of free radicals is the necessary process for obtaining the target product.This is consistent with the experimental verification results.The activation barrier of CuCl-catalyzed N-methyl hydrazine coupling reaction is lower than that of CuCl2,so the catalytic effect of CuCl on this reaction is better which is consistent with the optimized experimental conditions.The substituted methyl group in N-methylanthraquinone has an important effect on whether or not the target product can be obtained.The replacement of the methyl group with a hydrogen atom has been experimentally found to produce an intermediate product that forces the termination of the catalytic process,and the structure of the product is characterized.The same result is calculated.(2)The Density Functional Theory was used to analyze the microscopic mechanism of Pd-catalyzed self-coupling reaction of 2,4-Dimethylbenzoic acid in detail.At the B3LYP base group level(Pd uses a quasi-potential group SDD),the,structure of all the compounds in the reaction pathway of the benzoic acid coupling reaction was optimized and the vibration was analysised at the same level.Combining the calculated results with experimental characterization results,the correctness of the reaction mechanism was verified,and the decarboxylation process was described as the rapid control step of the reaction from the energy barrier point of view.