Preparation And Characterization Of Cu - Catalyzed C - N Coupling Reaction And Supported Catalysts Prepared By Montmorillonite

Ullmann coupling reaction is important for preparing natural products, drugs, and materials. Copper-catalyzed C-N coupling reactions are extensively studied because of its mild conditions, high efficiency and good functional compatibility. These reactions were generally explored in homogeneous or heterogeneous catalyst systems. Compared to homogeneous reactions, heterogeneous copper-catalyzed C-N coupling reactions exhibit obvious advantages:separability, recyclability and excellent catalytic activity. These advantages are consistent with the requirements of green chemistry which demands recycled resources for highly efficient reaction process and reduction of waste emissions. In heterogeneous reactions, heterogeneous ligands or supported catalysts play a vital role. However, synthesis processes of those materials were usually sophisticated with the consumption of resource increased. In order to reduce the consumption of resource, this paper selected natural montmorillonite as solid ligand. Montmorillonite, as a kind of cray, has unique layer structure which has a negative charge, particularly, and a large number of O atoms that coordinate metal ions and accelerate a catalytic cycle. The main contents of this study include two aspects:Firstly, montmorillonite promoted copper-catalyzed C-N coupling reactions of aryl halides and nitrogen heterocyclic were studied. The result showed that Cu(OAc)2gave the best effect, and the yields were from medium to good. Montmorillonite were recycled and characterized. The characterization results showed that montmorillonite obtained copper ion to promote the C-N coupling reaction. ED AX of montmorillonite indicated that approximately77%copper could be isolated from the reaction system. Copper valence was characterized by XPS, and the result showed that Cu(II) changed to Cu(I) in order to catalyze the reaction.Secondly, the solvent thermal reduction for preparing of montmorillonite-supported copper catalysts was studied. A series of montmorillonite-supported copper catalysts were successfully prepared. The effects of copper source, dispersant and montmorillonite for the catalytic activity were investigated. These catalysts were characterized by SEM, IR, XPS, XRD. Experimental results showed that the reducing solvent could facilitate the reduction of Cu(II) to Cu(I). The montmorillonite-supported copper catalyst afforded good yields, which was prepared in DMF with strong reductive ability. The catalyst was recovered in a large scale.