| The thesis consists of three parts as follows: Part I: ReviewHere we present an overview of the important achievements in the fields of dendritic catalysis, with an emphasis on homogeneous catalysis. Dendrimers that are functionalized with metal complexes at their periphery as well as a their core are discussed. Subsequently, dendritic catalysts that contain metal complexes throughout their structure and dendritic catalysts that operate without metal will be described. A summary of the various reactions catalyzed by dendritic catalysts is provided at the end of this chapter.Part II: The synthesis and the characterization of the ligands and the complexesPolymer supported dendrimer P-PAMAM(1.0-6.0G), (PAMAM abbreviated as polyamidoamin) has been prepared by reaction of chloromethylated polystyrene with ethylenedimine (EDA) and methyl acrylate (MA), and the reaction between P -PAMAM and SA (abbreviated as salicyaldehyde) gives the schiff-base like ligands P-PAMAMSA for the coordination with many metal ions such as Cu(II), Co(II),Ni(II), Mn(II), the 24 polymer supported denddritic complexes P-PAMAMSA (1.0~6.0G)-M(II) (M=Cu(II), Co(II), Ni(II), Mn(II)) were then obtained. The structures of these polymer supported ligands and complexes were characterized by means of IR, ICP and XPS. It was confirmed that the complexes have been prepared through the chemical reactions. The procedure for the preparation of the polymer-supported dendrimers was much simpler than that of literature. Each step only required filtering and washing the reaction mixture, avoiding of the most difficult procedure for the purification of the dendrimers and the waste of EDA andMA.Part HI: The catalytic properties of the P-PAMAMSA-M complexesThe complexes were first used as catalysts for the oxidation of cyclohexene, cumene and ethylbenzene by molecular oxygen in mild conditions. Their catalytic properties for the oxidation processes were investigated. The effects of reaction temperature, reaction time, the ratio of catalyst to substrate, the solvent, and the additives to the reactions as well as the recycling of the catalyst were also discussed in each of the subsections. The comparison of the products selectivity, the oxygen consumption for the same substrate among different oxidation processes was employed to find out the optimum condition for the oxidation of each processes.The reaction condition of this catalystic system was mild and the selectivity of products were high (for example: the oxidation of the cyclohexene had 49% selectivity of 2-cyclohexen-l-one, the oxidation of the cumene had 89% selectivity of cumene hydroperoxide (CHP), the oxidation of theethylbenzene had 61% selectivity of benzenemethanol).The results of oxidation show that all the 24 polymer supported dendrimer complexes exhibit promising catalytic properties for cyclohexene and cumene, theoxidaction of ethylbenzene were only can catalyst by P-PAMAMSA(1.0~6.0G)-Cu(II), when the other complexes were used, this reaction did not happened. |
