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Selective organic transformation based on heterogeneous photocatalysis has been attracted much attention.TiO2 photocatalysis can achieve the selective organic transformation under mild conditions, which has extensive worthiness of research and applicable prospects in the field of organic synthesis.Epoxides are usually used as versatile intermediates and raw materials for various kinds of valuable products, therefore, catalytic epoxidation of olefin is one of the fundamental reactions in organic synthesis.Classical methods for epoxidation of olefm hinge largely on the use of organic peracids in both industrial synthesis and laboratory research.In light of the increasing demand for green and sustainable chemistry, the development of an elegant catalytic system for olefm epoxidation is an important goal.The olefm oxidation can be carried out by TiO2 photocatalysis using O2 as oxidant,however, the main products are not epoxides, but carbonyl compounds.Hydrogen peroxide (H2O2) as an economically and environmentally friendly reagent is one of the most attractive reagents, which has become increasingly important for catalysis reaction in recent years.In this thesis, cis-cyclooctene epoxidation with H2O2 catalyzed by UV/TiO2 has been investigated.The main content of the thesis is as follows:Ⅰ: The role of TiO2 in cis-cyclooctene epoxidation in absence of UV light irradiation has been investigated.It is found that TiO2 is necessary for the cis-cyclooctene epoxidation and this reaction is a catalysis process.Ⅱ: The effect of the molar ratio of H2O2 to TiO2 on the cis-cyclooctene epoxidation has been prominently investigated.It is found that the UV light has no effect on the reaction at a low molar ratio of H2O2 to TiO2, while the significant acceleration effect by UV light is observed at a high molar ratio of H2O2 to TiO2.Moreover, the acceleration effect by UV light is irrelevant to the cis-cyclooctene concentration.Ⅲ: The inert species that formed on the TiO2 surface at a high molar ratio of H2O2 to TiO2 has been identified by isotope-labeled resonance UV Raman spectroscopy, it is confirmed that the inert species is assigned to the surface Ti-η2-peroxide, namely Ti(O2).Ⅳ: The decomposition property of TiO2 surface Ti-η2-peroxide has also been studied by using spectroscopy to monitor titration experiments.It is found that the surface Ti-η2-peroxide is very stable in absence of UV light irradiation at room temperature, while it can be easily decomposed in the presence of UV light irradiation.Therefore, the acceleration effect by UV light in the reaction of cis-cyclooctene epoxidation is responsible for photodecomposition of the inert Ti-η2-peroxide and regeneration of the active sites on the TiO2 surface.