Organometallic Immobilization And Their A Green Catalytic Performance Study

Most organic reactions are conducted in organic solvents and billion ton of organic solvents are used each year in the fine chemical and pharmaceutical industries for reaction and product isolation purposes. The discharge of large quantities of organic solvents eventually adds to environmental problems. A notable development is the use of water as an alternative non-polluting solvent for organic reactions since water has been the most innocuous substance on Earth and therefore the safest solvent possible. Numerous biochemical organic reactions affecting the living system have inevitably occurred in aqueous media with the help of enzymes. Thus, design of powerful catalysts plays a key role in realizing the water-medium clean organic reactions. To date, most studies are focused on homogenous organometallic catalysts for water-medium organic reactions due to the solubility limit. Although homogeneous catalysts work very well, their industrial applications are limited due to their difficult separation from the reaction system and their unable recycling use, which may increase cost and even lead to heavy-metal pollution in water. Design of immobilized organometallic catalysts seems a promising way to overcome above disadvantages. To obtain high catalytic efficiency, matchable with that of the corresponding homogeneous catalysts, the immobilized organometallic catalysts should remain both the effective chemical environment and the high dispersion degree of active sites. Recent progress in the mesoporous silica with catalytically active groups has highlighted the potential of utilizing these structurally uniform materials as a new generation of powerful heterogeneous catalysts. This thesis is comprised of 5 chapters. The first chapter is a brief introduction of green chemistry and immobilization of organometallic catalysts. The second chapter describes some typical characterization technologies involved in the present studies. The highlights are included in the following 3 chapters. Chapter 3 reports a new approach to synthesize a mesoprous Ru(II) organometallic catalyst (Ru-MOC) based on co-condensation of TEOS and Ru(II) organometallic silane in the presence of surfactant-assembly. During water-medium isomerization reactions, the as-prepared immobilized organometallic catalyst exhibits comparable activity and selectivity with the corresponding homogeneous Ru(II) organometallic catalyst and could be used repetitively, showing a good potential in industrial applications.Chapter 4 reports the applications of the as-prepared Ru-MOC other organic reactions, including both isomerization and reduction reactions. The experimental results demonstrate that Ru-MOC catalyst is of excellent universality. Meanwhile, several new Ru(II) organometallic silanes are prepared, which can co-assemble with TEOS to different types of materials with controllable shapes and morphologies. All these catalysts exhibit highly ordered structure, indicating that the co-assembly between organometallic silane and TEOS is an efficient way to design immobilized organometallic catalysts with ordered mesoporous structure, which can overcome the shortcomings of grafting method which usually lead to partial damage of mesoprous structure, leading to the reduced ordering degree of porous channels.Chapter 5 describes the synthesis of a novel gold(I) organometallic saline, which co-assembles with benzene bridged organosaline to prepare PMO-type immobilized Au(I) organometallic catalyst (Au-PMO). Such catalyst could be applied in the series water-media organic reactions with comparable activity and selectivity to the corresponding homogeneous catalysts and could be used repetitively.