Study On Baeyer-Villiger Oxidation Reaction Of Cyclohexanone Catalyzed By Heteroatom Mesoporous Molecular Sieves

The Baeyer-Villiger oxidation of ketones or cyclic ketones is an important reaction in organic synthesis,especially in the synthesis of lactones.In order to avoid the problems of environmental pollution and post-processing of traditional peroxic acid oxidants,this paper chooses green hydrogen peroxide as oxidant and modified mesoporous molecular sieve as catalyst for heterogeneous reaction system.This article mainly contained the following three systems:Pure silica mesoporous molecular sieve SBA-15 was synthesized by hydrothermal method,and metal-doped mesoporous molecular sieves M-SBA-15?M=Al,Sn,Zr,Ti?were prepared by maceration method.The obtained mesoporous molecular sieves were characterized by X-ray powder diffraction?XRD?,N₂ adsorption-desorption,infrared spectroscopy?FT-IR?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,temperature desorption ammonia NH₃-TPD and inductively coupled plasma emission spectroscopy?ICP-AES?methods.The obtained mesoporous molecular sieve Sn-SBA-15 has been used to catalyze Baeyer-Villiger oxidation of cyclohexanone.The optimized process conditions were as follows: the Si/Sn ratio of Sn-SBA-15 40,1,2-dichloroethane as solvent,the reaction temperature 80 °C,the reaction time 9 h,the molar ratio of H₂O₂ to cyclohexanone 1.5,the amount of catalyst 0.30 g.Under the optimum reaction conditions,the conversion of cyclohexanone and the selectivity of lactone were 89.86% and 79.94%,respectively.The recycling performance of the catalyst was investigated under the optimum reaction conditions.The results showed that the catalyst activity obviously decreased when the catalyst was used for the third time.The mesoporous molecular sieve MTS-9 was synthesized by hydrothermal method using TS-1 precursor as the guide agent,and Sn-doped mesoporous molecular sieve Sn-MTS-9 was prepared by maceration method.The synthesized mesoporous molecular sieves were characterized by XRD,N₂ adsorption-desorption,FT-IR,SEM,TEM,NH₃-TPD and ICP-AES methods.The obtained mesoporous molecular sieve Sn-MTS-9 was used to catalyze Baeyer-Villiger oxidation reaction of cyclohexanone.The optimum conditions were as follows: the Si/Sn ratio of Sn-MTS-9 30,1,2-dichloroethane as solvent,the reaction temperature 80 °C,the reaction time 7 h,the molar ratio of H₂O₂ to cyclohexanone 1.5,the amount of catalyst 0.20 g.Under the optimum conditions,the conversion of cyclohexanone and the selectivity of lactone were 92.92% and 92.60%,respectively.The recyclability of catalyst was tested.The result showed that the catalytic activity of Sn-MTS-9 decreased after 4 cycles.The mesoporous molecular sieve MAS-7 was synthesized by hydrothermal method using Beta precursor as the guide agent,and Sn-doped mesoporous molecular sieve Sn-MAS-7 was prepared by maceration method.The synthesized mesoporous molecular sieves were characterized by XRD,N₂ adsorption-desorption,FT-IR,SEM,TEM,NH₃-TPD and ICP-AES methods.The obtained mesoporous molecular sieve Sn-MAS-7 was used to catalyze Baeyer-Villiger reaction of cyclohexanone.The optimum conditions were as follows: the Si/Sn ratio of Sn-MAS-7 80,1,2-dichloroethane as solvent,the reaction temperature 80 °C,the reaction time 7 h,the molar ratio of H₂O₂ to cyclohexanone 1.5,the amount of catalyst 0.20 g.Under the optimum conditions,the conversion of cyclohexanone and the selectivity of lactone were 92.21% and 97.72%,respectively.The recyclability of catalyst was tested.The result showed that the catalytic activity of Sn-MAS-7 decreased after 4 cycles.In this paper,heterogeneous reaction systems for the Baeyer-Villiger oxidation of cyclohexanone catalyzed by modified mesoporous molecular sieves were established.These catalytic systems showed good catalytic activity and good separation between the product and the catalyst.The catalysts could be recycled.The paper provides a new theoretical support for the Baeyer-Villiger oxidation of cyclohexanone with hydrogen peroxide solution as oxidant.