Preparation Of Organic Supported Solid Base And Study Of Catalytic Oxidation

Organic supported solid base is one of the important heterogeneous catalysts for many catalytic reactions,the catalytic performance is highly dependent on the characteristics of the support,such as the chemical stability,inherent porosity,mass transfer efficiency,etc.In recent years,much effort has been devoted to generate the strong basic sites on functional supports.The generation of the strong basic sites on the support usually include loading of base precursors and subsequent calcination.However,the thermal decomposition point for the base precursors is quite high,such a high calcination temperature will lead to the collapse of majority porous support structure and limit the formation of strong basic sites on many novel supports.To avoid structure collapse,according to the nature of hypercrosslinked polymer?HCP?,we reported for the first time that strong basic sites could be generated on the HCP through the reducing groups functionalized strategy.In this dissertation,K-HCP-1,K-HCP-2 were synthesized,its structure was characterized and the formation mechanism of basic sites has been deeply explored.The research used K-HCP-1,K-HCP-2 as catalysts and catalytic oxidation of fluorenones with fluorenes and catalytic oxidative coupling of benzylamines to imines as mode reactions.The main research contents of this thesis are as follows:Based on Friedel-Crafts alkylation reaction,HCP-1,HCP-2,HCP-3 and HCP-4 with high porosity and high crosslinking were synthesized.Two basic precursors of KNO₃ and NaNO₃were loaded into the porous polymer channels of HCP-1,HCP-2,HCP-3 and HCP-4respectively by impregnation method.In N₂ atmosphere,six solid basic catalysts were obtained by calcining at a series of temperatures:K-HCP-1,K-HCP-2,K-HCP-3,K-HCP-4,Na-HCP-2,Na-HCP-4.The base amounts of K-HCP-1,K-HCP-2 were 1.8 mmol g^-11 and 1.9mmol g^-11 measured by the acid-base titration,which were close to the theoretical basic value.The active sites of K-HCP-1 and K-HCP-2 were confirmed as medium and strong bases by CO₂-TPD,so the optimal solid bases were K-HCP-1 and K-HCP-2,the corresponding degradation temperatures of KNO₃ were respectively 350 ? and 320 ?,which were far lower than the traditional heat-induced degradation temperatures.TG-MS characterization was used to explain the strong interaction between HCP-1,HCP-2 and KNO₃,it was confirmed that the strong redox effect between the reducing group?C=C,CHO?on HCP-1,HCP-2 and KNO₃,which promoted the formation of strong basic sites at lower temperature.By means of solid nuclear magnetism,X-ray photo electron spectroscopy and elemental analysis,the transformation of reducing groups?C=C,CHO?before and after calcination were investigated.The results showed that the vinyl partly was oxidized to aldehyde and carboxylic acid,the aldehyde partly was oxidized to carboxylic acid.Using K-HCP-1 with calcination temperature of 350°C as catalyst and catalytic oxidation of fluorenones with fluorenes as a model to explore K-HCP-1 catalytic performance of methylene oxidation.The results showed that the reaction rate of fluorenes was above 99%and the yield of fluorenones was above 99%at 160°C,0.5 MPa O₂,100 mg K-HCP-1 and DMF as solvent.K-HCP-1 was used to catalyze the oxidation of various methylene substrates.The results showed that the conversion rate of substrates was no less than 70%,and K-HCP-1could successfully catalyze the oxidation of substrates into the required ketones,which indicated that organic supported solid base had a potential application prospect in the aerobic oxidation of methylene compounds.Using K-HCP-2 with calcination temperature of 320°C as catalyst and explore the catalytic oxidative coupling performance of benzylamines to imines.The results showed that the reaction rate of benzylamines was above 99%and the yield of imines was 91%at 140°C,0.5 MPa O₂,50 mg K-HCP-2 and CH₃OH as solvent.K-HCP-2 was used to catalyze the oxidation coupling of various amines substrates.The results showed that the conversion rate of substrates was no less than 80%,and K-HCP-2 could successfully catalyze oxidation coupling substrates into the required imines,which indicated that organic supported solid base had a potential application prospect in the oxidative coupling of amines.