| Suzuki, Heck and Sonogashira reactions are the powerful methods of C-C formation, which have being applied in the synthesis of pharmaceuticals, natural products and advanced functional materials. Organic solvent emission has caused the serious environment pollution. In addition, Pd is a kind of noble metals owning great physical and chemical properties. How to improve its utilization percent has always been a hot topic due to it is so rare (about 1 of 100 millions) in the earth’s crust. "Green" and "Practical ability" have been becoming an urgent project for chemist to sustainable development. In recent years, Cross-coupling reactions catalyzed by palladium in green media have made great progress. Considering the great value of water media and noble metal Pd in the field of organic catalysis, and the disadvantage. The dissertation focuses on developing the use of water in place of organic solvents and the development of new catalysts/ligands to extend, promote and perfect the Suzuki, Heck and Sonogashira reactions in "green" solvents.The main contents of the thesis are listed as follows:As a stating point, a new protocol for the thermoregulated ligand PEG-N-Methyl-Imidazole-Salt-Pd(OAc)2-catakyzed Suzuki, Heck and Sonongashira reactions using water as sole medium was developed. The result showed that this thermoregulated system demonstrated excellent catalytic activities. In addition, the solution of PEG-N-Methyl-Imidazole-Salt-Pd(OAc)2 could be recycled five times without significant decrease in activity, and the yield of product was also up to 80%.Polyethylene glycol triphenylphosphonium bromide salts (PEG-TPPB) was used to the Suzuki and Sonogashira reactions in water catalyzed by self-nano Pd/C as surfactant. The results showed PEG-TPPB/H2O-nano Pd/C could be promoted the cross-coupling reaction in air without any other ligand. In addition, the whole catalytic system could be reused for several times with a slightly decrease in its activity.A novel Cross-linked polyallylamine polymer supported iminopyridylphosphine palladium (Ⅱ) complex was designed and prepared. It was found to be an efficient catalyst for Suzuki reactions in EtOH/H2O, and the coupling of a range of different aryl iodides and aryl bromides with substituted phenylboronic acids could proceed well within 1-3 h at 80 ℃ to give excellent yields (88-99%). The catalytic system could tolerate broad range functional groups, and was simply recovered by filtration. The results showed the supported palladium catalyst was used five times without any loss of activity, and the yield of the fifth recycled experiment was up to 95%.Effects are also made to design and prepare three different highly water dispersible /magnetic Fe3O4 nanoparticle-supported palladium complexes. The structures of prepared materials were characterized by various techniques including FT-IR, TEM, VSM, XPS, XRD and TGA, and were applied successfully for Suzuki and Heck reactions in water. Among them, Fe3O4@PEG-AIm-NH2-IL-Pd (0) could make the coupling reaction in pure water effectively. The results demonstrated that these magnetic materials supported palladium catalysts not only had highly stability and excellent catalytic activity, but also could be simply recovered by magnetic separation. The cycled experiments showed these novel supported palladium catalysts could be reused five times without significant loss of activity. |
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