The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-...The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of the radical reaction and improve the yield of PTA.展开更多
Although different NbO_(x) units are present in Nb_(2)O_(5)‐based catalysts,the correlations between these structures and activity remain unclear,which considerably hinders the further development of Nb_(2)O_(5) phot...Although different NbO_(x) units are present in Nb_(2)O_(5)‐based catalysts,the correlations between these structures and activity remain unclear,which considerably hinders the further development of Nb_(2)O_(5) photocatalysis.Herein,we utilized N‐hydroxyphthalimide(NHPI)as the probe molecule to distinguish the role of different NbO_(x) units in the activation of C–H bond under visible light irradia‐tion.With the addition of NHPI,Nb_(2)O_(5) catalysts with highly disordered NbO_(6) units exhibited higher activities than that with slightly disordered NbO_(6) units(419‒495 vs.82μmol·g^(-1)·h^(-1))in photocata‐lytic selective oxidation of ethylbenzene.Revealed by Raman spectra,electron paramagnetic reso‐nance spectra,and transmission‐electron‐microscopy images,highly disordered NbO_(6) units were confirmed to act as the active sites for the transfer of photogenerated electrons from NHPI,pro‐moting the generation of phthalimide‐N‐oxyl(PINO)radicals for the enhanced conversion of ethylbenzene under visible light irradiation.This study provides guidance on the role of local NbO_(x) units in Nb_(2)O_(5) photocatalysis.展开更多
Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediate...Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediates for organic synthesis and industrial processes.Among the developed oxidationprotocols,innovative strategies using hydroxyimide organocatalysts in combination with metallicor metal‐free cocatalysts have attracted much attention because of the good activities andselectivities of such catalysts in the oxo functionalization of hydrocarbons.This method is based onthe reaction using N‐hydroxyphthalimide,which was first reported by Ishii’s group in the1990s.Although the important and wide‐ranging applications of such catalysts have been summarizedrecently,there are no reviews that focus solely on oxidation strategies using multi‐nitroxy organocatalysts,which have interesting properties and high reactivities.This review covers the concisesynthetic methods and mechanistic profiles of known multi‐nitroxy organocatalysts and summarizessignificant advances in their use in efficient aerobic oxidation.Based on a combination of experimentaland theoretical results,guidelines for the future rational design of multi‐nitroxy organocatalystsare proposed,and the properties of various model multi‐nitroxy organocatalysts are predicted.The present overview of the advantages,limitations,and potential applications of multi‐nitroxyorganocatalysts can provide useful tools for researchers in the field of selective oxidation.展开更多
基金supported by the National Natural Science Foundation of China(21376208)the Zhejiang Provincial Natural Science Foundation for Distinguished Young Scholars of China(LR13B030001)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(J20130060)the Fundamental Research Funds for the Central Universitiesthe Program for Zhejiang Leading Team of S&T Innovation~~
基金supported by the National Natural Science Foundation of China(Grant No.20072025).
文摘The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of the radical reaction and improve the yield of PTA.
文摘Although different NbO_(x) units are present in Nb_(2)O_(5)‐based catalysts,the correlations between these structures and activity remain unclear,which considerably hinders the further development of Nb_(2)O_(5) photocatalysis.Herein,we utilized N‐hydroxyphthalimide(NHPI)as the probe molecule to distinguish the role of different NbO_(x) units in the activation of C–H bond under visible light irradia‐tion.With the addition of NHPI,Nb_(2)O_(5) catalysts with highly disordered NbO_(6) units exhibited higher activities than that with slightly disordered NbO_(6) units(419‒495 vs.82μmol·g^(-1)·h^(-1))in photocata‐lytic selective oxidation of ethylbenzene.Revealed by Raman spectra,electron paramagnetic reso‐nance spectra,and transmission‐electron‐microscopy images,highly disordered NbO_(6) units were confirmed to act as the active sites for the transfer of photogenerated electrons from NHPI,pro‐moting the generation of phthalimide‐N‐oxyl(PINO)radicals for the enhanced conversion of ethylbenzene under visible light irradiation.This study provides guidance on the role of local NbO_(x) units in Nb_(2)O_(5) photocatalysis.
基金supported by the China Postdoctoral Science Foundation (2014M551746)~~
文摘Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediates for organic synthesis and industrial processes.Among the developed oxidationprotocols,innovative strategies using hydroxyimide organocatalysts in combination with metallicor metal‐free cocatalysts have attracted much attention because of the good activities andselectivities of such catalysts in the oxo functionalization of hydrocarbons.This method is based onthe reaction using N‐hydroxyphthalimide,which was first reported by Ishii’s group in the1990s.Although the important and wide‐ranging applications of such catalysts have been summarizedrecently,there are no reviews that focus solely on oxidation strategies using multi‐nitroxy organocatalysts,which have interesting properties and high reactivities.This review covers the concisesynthetic methods and mechanistic profiles of known multi‐nitroxy organocatalysts and summarizessignificant advances in their use in efficient aerobic oxidation.Based on a combination of experimentaland theoretical results,guidelines for the future rational design of multi‐nitroxy organocatalystsare proposed,and the properties of various model multi‐nitroxy organocatalysts are predicted.The present overview of the advantages,limitations,and potential applications of multi‐nitroxyorganocatalysts can provide useful tools for researchers in the field of selective oxidation.
