Preparation Of Co-N-C Composite And Its Utilization In The Selective Oxidation Of Aromatic Side Chains

With the development of material science,a wide variety of N-doped carbon?N-C?materials have been come into the view of organic chemist because of their superior performance and easy preparation.C-N materials,especially loaded with transition metals,have been widely used in organic synthesis.In this thesis,a kind of Co-N-C composite was prepared and utilized to catalyze liquid-phase oxidation.The Co-N-C catalyst shows great efficiency in selective oxidation of aromatic side chains and allylic position of olefins.Firstly,the novel Co-N-C composite was synthesized by using ball-milling method with melamine and Co?NO3?2.6H2 O as starting materials.Then,the composite was characterized by SEM,BET,HRTEM,XRD,XPS and FTIR.The results showed that the melamine and cobalt salt precursors should be reacted each other to form the Co-N-C materials,which had a microporous structure.The melamine might undergo a polymerization process to form a material similar with g-C₃N₄.The catalytic performances of the prepared Co-N-C catalyst was investigated by selective liquid-phase oxidation of C-H bonds.The Co-N-C catalyst shows great efficiency in selective oxidation of aromatic side chains and allylic position of olefins under relative mild conditions with atmospheric oxygen as oxidant.0.5mol% of Co-N-C gave a high conversion and selectivity of the oxidation of ethylbenzene to acetophenone?92.8% conversion of ethylbenzene and 95.45% selectivity to acetophenone?.Further more,hectogram-scale oxidation was also allowed.It was noteworthy that excellent recyclability was also observed for the catalyst: high conversion and selectivity were achieved even after five recycles.In summary,the Co-N-C material was prepared by a novel,inexpensive and simple method,and good catalytic properties were observed in selective oxidation of aromatic side chains and allylic position of olefins.The catalytic oxidation shows good functional group tolerance and wide substrates scope under mild reaction conditions.