Research On Catalytic Activation Of C-H Bond By Anderson-Type Heteropoly Acid Catalyst

With the continuous development of the concept of green environmental protection,the role of catalysts in organic synthesis is becoming more and more significant,especially in terms of reducing activation energy,whether the catalyst can be recycled and whether it is environmentally friendly is of particular concern.However,due to the important role of metal catalysts and photocatalysis in organic synthesis,as well as the different catalytic effects of specific catalysts on chemical reactions,it is very difficult to find a suitable green and recyclable catalyst to achieve the effect of the formed catalytic reaction.The catalytic activation of C-H bonds is more common in redox reactions,and oxidation to aldehydes,ketones,and acids has many existing experimental support.Especially in the process of oxidation to aldehydes,benzaldehyde,as an important raw material for industrial production,occupies an important position in the chemical production process.However,because aldehydes are easily oxidized to acids,it is extremely challenging to control the reaction in the process of aldehydes.Sexual experiment.In the existing oxidation experiments,the catalyst is often harmful to the environment,toxic and harmful,and the synthesis process is very complicated.Based on this,this thesis focuses on an emerging catalyst-polyoxometalate to conduct experimental research,and select a suitable configuration of polyoxometalate for the catalytic activation of C-H bonds.The main research contents are as follows:1.The Anderson type polyoxometalate with Cr as the central metal atom was used as a catalyst,and under the condition of 30%H₂O₂ as an oxidant,the process of catalytic oxidation of toluene to benzaldehyde was studied.The catalyst has good catalytic oxidation properties for a variety of aromatic derivatives,and can be oxidized under mild conditions,staying in the aldehyde process,and the yield can reach 99%,with almost no by-products.The green environmental protection of the polyacid metal catalyst is well demonstrated.After repeated experiments,it is found that after six cycles of experiments,there is almost no loss of activity,and it can still be used for the oxidation of toluene.2.On the basis of toluene research,the catalyst is still used.Under the same reaction conditions,the benzene ring,cyclohexane,pyridine,ethylbenzene and other substances are oxidized,and it is found that the corresponding oxidation products can be generated,indicating that this type of Anderson-type catalyst has a positive effect on the activation and oxidation of C-H bonds,and the reaction conditions were screened,and the optimal conditions were selected.For some heterocycles,such as those containing nitrogen atoms,sulfur atoms,and oxygen atoms,it has been found that the reaction can also proceed and good yields are obtained.The reaction mechanism we inferred was verified by calculation,and the verification by these experiments showed that the polyacid catalyst has a universality and effectively catalytic oxidation and single selectivity.As a new type of green catalyst,the polyacid catalyst can be recycled and recovered after the reaction is completed,conforms to the concept of green and environmental protection,and has a good prospect in the process of industrialized scale-up production.