Research On Pd Metal Supported On Titanium Dioxide In Suzuki-Miyaura Coupling Reactio

C-C bond coupling reaction plays an important role in the field of organic synthesis.Now it is widely used in the synthesis of medicine,agricultural chemicals and natural chemicals.Among the existing C-C bond coupling reactions,Suzuki Miyaura coupling reaction has become one of the most effective methods to synthesize C-C bond because of its mild reaction conditions,excellent compatibility and excellent selectivity.The catalyst prepared by Pd metal can show high catalytic activity for Suzuki-Miyaura coupling reaction.However,due to the problems of little storage of Pd metal in nature and high price,it is necessary to develop new methods to make Pd catalyst can be used for many times and reduce Pd consumption.The lamellar structure of TiO₂can have a good dispersion effect on Pd metal,prevent the aggregation of Pd catalyst and increase the reusability of Pd.The specific research contents are as follows:1.TiO₂ microspheres with lamellar structure were synthesized by one-step hydrothermal method,and then Pd metal was uniformly loaded by equal volume impregnation,and then calcined at different temperatures to obtain Pd/TiO₂catalyst.The catalyst is Pd/TiO2 calcined at 350℃,the temperature is 80℃,the solvent is ethanol and water 1:1,and the base is potassium carbonate.Moreover,the catalyst can be reused for 4 times,and TONs can reach more than 10⁵.The substrates of the reaction were also investigated.The reaction can still show good activity under different substrates.2.1x1cm monolithic titanium sheet is selected as the substrate of the catalyst,and the layer TiO₂is grown in situ on the titanium sheet through etching.Then,Pd metal is loaded on the titanium sheet through the process of precipitation and deposition,and the monolithic catalyst Pd/TiO₂is obtained through high-temperature calcination.The catalyst was used to catalyze Suzuki-Miyaura coupling reaction,and the optimal reaction conditions were selected.The monolithic catalyst was Pd/TiO₂calcined at 450℃,the temperature was 80℃,the solvent was ethanol and water 1:1,and the base was triethylamine.After the reaction,tons can reach 2x10⁵,and the catalyst,as an integral catalyst,is more convenient in the process of recycling,and has certain reusability.It also has good reactivity in the reactions of different substrates.