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Highly Efficient Catalytic Oxidation of Inert C(sp 3 )–H Bonds by the Synergistic Effect of Copper Nanoparticles/N‐Doped Graphene
Author(s) -
Sun Wei,
Gao Lingfeng,
Feng Xue,
Sun Xu,
Zheng Gengxiu
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201701286
Subject(s) - graphene , cyclohexanol , chemistry , catalysis , cyclohexanone , selectivity , nanoparticle , inorganic chemistry , copper , cyclohexane , photochemistry , nanotechnology , organic chemistry , materials science
The applicability of Cu is still limited in the heterogeneous catalytic oxidation of C(sp 3 )–H bonds. This problem was resolved by exploiting the synergistic effect existing between Cu nanoparticles (Cu NPs) and N‐doped graphene. We demonstrate a highly efficient, green protocol for the catalytic oxidation of inert C(sp 3 )–H bonds with only oxygen as the oxidant catalyzed by Cu NPs/N‐doped graphene (Cu‐N‐rGO). The new composite materials were obtained through a very simple one‐pot solvothermal process. Remarkably, newly prepared Cu‐N‐rGO showed 34.5 % conversion and 89.2 % selectivity for the catalytic oxidation of cyclohexane to KA oil [mixture of cyclohexanone (K) and cyclohexanol (A)] in a single cycle and thus exhibited significantly higher efficiency than the N‐free Cu catalysts. Cu‐N‐rGO has good stability because the doped nitrogen atoms allow strong interactions between the Cu species and graphene, so that the conversion and selectivity can be maintained over five runs. The delicate relationship between the Cu NPs and nitrogen was investigated by accurate control of the ratio of nitrogen and Cu in doped graphene. A hypothesized free‐radical chain mechanism and a peroxidative oxidation process were proven and explained, and the synergistic effect of the Cu NPs and N‐doped graphene in facilitating the oxidation process was also elucidated.