New Carbene Complexes And Their Catalytic Abilities In Hydroformylation Of Olefins And Suzuki Cross-coupling Reaction

Since the isolation and characterization of the stable N-heterocycliccarbenes (NHCs) by Arduengo in 1991, these compounds have shown great glamour incatalysis, in which they serve both as nucleophilic catalysts directly and as ligands intransition metal-mediated reactions. The strongσ-donating characters of NHCscombined with poorÏ€-accepting properties make metal centers of their complexes tobe electron-rich compared to the corresponding phosphine complexes, resulting in thatthe carbene ligands appear not to dissociate from the metal centers and their complexestend to be highly active in oxidative addition steps. These features of NHCs have madesignificant progresses in improving the performance of some catalysts previous withphosphines, especially in Ru-catalyzed olefin metathesis and Pt-catalyzed olefinhydrosilylation. We have successfully incorporated four imidazolium salt with twobulky subunits derived from D-glucose, and the rhodium complexes with thecorresponding new carbene ligand.Suzuki cross-coupling of aryl bromides with arylboronic acid is one of the mosteffective methods to form biphenyl derivatives. It has become an excellent tool for themodern organic synthesis and has been extensively utilized in the preparations oforganic optoelectronics, medicines and fine chemicals.This thesis is mainly focused on three parts.The first chapter briefly summarized the variety, structural, preparation ofN-heterocyclic carbenes and its application in some catalytic reactions.The second chapter investigated the synthesize of a new N-heterocycliccarbene-rhodium(NHC-Rh) complex, and characterized by ¹H NMR, ¹³C NMR, IR,HRMS. The NHC-Rh complex was application in hydroformylation of styrene. Theconversion of styrene increases with the temperature increasing, but aldehyde molarration of iso-aldehyde to normal reduced; the conversion of styrene increases with thepressure of synthesis gas increasing, but affect the aldehyde molar ration ofiso-aldehyde to normal little; With the increased ration of the styrene/catalyst, the conversion (from 9% to 72%) of styrene and the aldehyde molar ration of iso-aldehydeto normal reduced. Under the conditions of 60℃, 5.0MPa, [styrene]/[Rh]=400 theconversion of aldehyde is about 99%, the molar ration of iso-aldehyde to normal is93/7. Under the conditions of 70℃, 5.0 MPa, [decene]/[Rh]=400 the conversion ofaldehyde is about 95%, the molar ration of normal to iso-aldehyde is 70/30., Under theconditions of 60℃, 5.0 MPa, [methyl acrylate]/[Rh]=400 the conversion of aldehyde isabout 99%, the molar ration of normal to iso-aldehyde is 5/95.The third chapter investigated the synthesize of a new tetrahydro-pyrimidiniumsalt, and characterized by ¹H NMR, ¹³C NMR, IR, HRMS. Thetetrahydro-pyrimidinium salt was application in Suzuki cross-coupling of4-bromotoluene and phenylboronic acid. Under the selected reaction conditions: 80℃,NaOBu^t, dioxane S/Pd(OAc)₂=100/1 (mol/mol), Pd(OAc)₂/ligand=1/1 (mol/mol),systerm can afford 92% yield in 3 hours.Two new catalysts NHC-Rh complex and tetrahydro-pyrimidinium salt wassynthesized, and applied in catalytic reaction, which obtains good effect.