The Preparation Of Functionalized Graphene Materials And Their Application In The C-N Coupling Reaction And Knoevenagel Condensation

The functionalized graphene materials were systematically investigated for C- N coupling reactions and Knoevenagel condensation in this paper. These multifunctional graphene materials were synthesized through a facile chemical reaction, and characterized by different method. The main studies were as follows:Firstly, the copper graphene composite(Cu-rGO) was prepared by the situ chemical reduction, and characterized by a variety of techniques, including Fourier transform infrared spectroscopy(FT- IR), X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and X-ray photoelectron spectroscopy(XPS). The results showed that the copper catalyst had been successfully supported on the graphene sheets and the divalent copper was obvserved. In the investigation of catalytic performance, the Cu-rGO material as a heterogeneous catalyst for C-N coupling reactions could be obtained good catalytic activity, and the catalyst was used at low dosage, as well as could be easily separated and recycled from the reaction mixture.Next, the graphene oxide(GO) was modified by the amidation between amino group of L-amino acids and the carbonyl of GO, and then the Cu NPs were immobilized on the amino acids- grafted graphene sheets by a simple situ chemical reduction. All the samples were analyzed by different characterization in details, including atomic force microscopy(AFM), and inductively coupled plasma-atomic emission spectrometry(ICP-AES). These results showed that the functionalized graphene materials as supports could further enhance the ability of immobilization of metallic nanoparticles. At the same time, the amino acids supported on the graphene sheets have the effect of electronic modification for these nanoparticles. These materials were also used as heterogeneous catalysts to catalyze the C-N coupling reaction, and the enhanced catalytic performance could be obtained as compared with the Cu-rGO catalyst. The results implied that the cooperative catalysis of amino acids had an important effect for the C-N coupling reactions. Additionally, this article systematically researched the application and recyclability of the L-tyrosine-grafted graphene copper catalyst(Tyr-G-Cu) in coupling reactions, and a leaching and re-deposition of the active Cu species was observed by a typical hot filtration test.Finally, two solid-base graphene materials were produced in this work, and evaluated their catalytic activity for Knoevenagel condensation. On the one hand, the malononitrile-functionalized graphene derivatives were synthesized by the reaction of malononitrile with GO, and then reduced by situ chemical reaction to obtain the amino-graphene materials(G-NH2). On the other hand, the alkaline Llysine was grafted on the GO sheets, and the L-lysine functionalized graphene(Lys-GO) could be obtained. G-NH2 and Lys-GO materials have weak alkalinity by the identification of the CO2 adsorption experiment. As compared with G-NH2, the Lys-GO material has higher alkalinity. The experiment results showed that GNH2 and Lys-GO materials as catalysts could catalyze Knoevenagel condensation with good yields. The catalytic performance is relevant to the alkalinity of two solid-base graphene materials.