Novel reusable MnOx‐N@C catalyst has been developed for the direct oxidation of N‐heterocycles under solvent‐free conditions using TBHP as benign oxidant to give the corresponding N‐heterocyclic ketones. The catal...Novel reusable MnOx‐N@C catalyst has been developed for the direct oxidation of N‐heterocycles under solvent‐free conditions using TBHP as benign oxidant to give the corresponding N‐heterocyclic ketones. The catalytic system exhibited a broad substrate scope and excellent regi‐oselectivity, as well as being amenable to gram‐scale synthesis. This MnOx‐N@C catalyst also showed good reusability and was successfully recycled six times without any significant loss of activity.展开更多
Here,we demonstrate a photochemical strategy to site-specifically deposit Pd atoms on Au nanoparticles.The high-sensitivity low-energy ion scattering spectra combined with the X-ray photoelectron spectra reveal that t...Here,we demonstrate a photochemical strategy to site-specifically deposit Pd atoms on Au nanoparticles.The high-sensitivity low-energy ion scattering spectra combined with the X-ray photoelectron spectra reveal that the surface electronic structure of Pd can be continuously regulated by tailoring the Pd-to-Au molar ratio and the location of Pd atoms in Au Pd nanoparticles.It is revealed that electron-rich Pd atoms are considerably more active than the net Pd atoms in aerobic alcohol oxidation.Remarkably,the catalyst with the most electron-rich Pd sites(binding energy downshift:1.0 e V)exhibits an extremely high turnover frequency(~500000 h-1 vs 12000 h-1 for that with net Pd atoms)for solvent-free selective oxidation of benzyl alcohol,which is,to the best of our knowledge,the highest value ever reported.Kinetic studies reveal that electron-rich Pd atoms can accelerate the oxidation of benzyl alcohol by facilitating C-H cleavage,as indicated by the significant reduction in the activation energy as compared to net Pd atoms.展开更多
We examined the puzzling mechanism for Cu-catalyzed meta-C-H arylation reaction of anilides by diaryliodonium salts through systematic theoretical analysis. The previously proposed anti-oxy-cupration mechanism featuri...We examined the puzzling mechanism for Cu-catalyzed meta-C-H arylation reaction of anilides by diaryliodonium salts through systematic theoretical analysis. The previously proposed anti-oxy-cupration mechanism featuring anti-1,2- or anti-1,4-addition of cuprate and oxygen to the phenyl ring generating a meta-cuprated intermediate was excluded due to the large activation barriers. Alternatively, a new amide-directed carbocupration mechanism was proposed which involves a critical rate- and regio-determining step of amide-directed addition of the Cu（III）-aryl bond across the phenyl C2=C3 double bond to form an orthocuprated, meta-arylated intermediate. This mechanism is kinetically the most favored among several possible mechanisms such as ortho-or para-cupration/migration mechanism, direct meta C-H bond cleavage mediated by Cu（III） or Cu（I）, and Cu（III）-catalyzed ortho-directed C-H bond activation mechanism this mechanism has been shown to Furthermore, the predicted regioselectivity based on favor the meta-arylation that is consistent with the experimental observations.展开更多
The site-selective C-H fluorination of heteroarenes is a straightforward approach to accessing valuable heteroaryl fluorides but remains a formidable challenge.Herein,we report a general strategy for visible-light-ind...The site-selective C-H fluorination of heteroarenes is a straightforward approach to accessing valuable heteroaryl fluorides but remains a formidable challenge.Herein,we report a general strategy for visible-light-induced C-H fluorination of heteroarenes via the merger of N-F fluorinating reagents and silane.Electron paramagnetic resonance experiments provide evidence for the homolytic cleavage of the N-F bond under blue light-emitting diode irradiation,which is the key step in the process.This transformation is metal-free,photocatalysts-free,and site-selective under mild reaction conditions(ambient temperature,visible-light irradiation,tolerant to H2O).The robustness of this protocol has also been highlighted by late-stage modification of complex and medicinally relevant molecules.展开更多
Exploring new heterogeneous catalysts to achieve efficient C-H bond oxidation is momentous in industrial chemical production.Herein,three Fe-incorporated polyoxometalate-encapsulated metal-organic frameworks(POM@MOFs)...Exploring new heterogeneous catalysts to achieve efficient C-H bond oxidation is momentous in industrial chemical production.Herein,three Fe-incorporated polyoxometalate-encapsulated metal-organic frameworks(POM@MOFs),[Fe(H_(2)O)_(3)(dtb)][Fe(dtb)_(2)][HBW_(12)O_(40)]-12H_(2)O(1),[Fe(H_(2)O)2(dtb)]_(2)[Fe(dtb)_(2)(Hdtb)][SiW^(Ⅵ)_(9)W^(Ⅴ)_(3)O_(40)]·16H_(2)O(2),[Fe(H_(2)O)_(2)]_(4)(dtb)_(5)[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]_(2)·18H_(2)O(3),(dtb=1,4-di[4H-1,2,4-triazol-4-yl]-benzene),were hydrothermally synthesized for catalytic C-H bond oxidation.They exhibited three-dimensional(3-D)POM-based metal-organic host-guest frameworks with diverse cages.In compound 1,cationic metal-organic frameworks constructed by binuclear[Fe_(2)(dtb)_(6)(H_(2)O)_(2)]^(4+)clusters and dtb ligands present a pcu alpha-Po primitive cubic topological net and abundant twisted quadrangular prism-shaped cages,in which the monoprotonated[HBW_(12)O_(40)]^(4-)polyoxoanions are encapsulated.In compound 2,two-dimensional(2-D)cationic metal-organic layers constructed by trinuclear[Fe_(3)(dtb)_(6)(H_(2)O)_(4)]^(6+)clusters and dtb ligands display a sql/Shubnikov tetragonal plane net topology,in which the rhomboid-shaped metal-organic windows in adjacent parallel-arranged 2-D layers are enclosed to form an open parallelepiped cage.The[SiW^(Ⅵ)_(9)W^(Ⅴ)_(3)O_(40)]^(7-)poly-oxoanions locate in the parallelepiped cages between 2-D bilayers.In compound 3,the 3-D cationic metal-organic frameworks constructed by binuclear[Fe_(2)(dtb)_(3)(H_(2)O)_(4)]^(4+)clusters and dtb ligands possess a bnn hexagonal BN topology,in which the hexagonal prismatic metal-organic cages accommodate four[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]^(4-)poly-oxoanions.Employing diphenylmethane(DPM)oxidation as C-H bond oxidation model reaction,compounds 1-3 displayed distinct catalytic activities owing to the synergistic effect of polynuclear Fe nodes and poly-oxoanions.Among them,[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]^(4-)-contained compound 3 exhibited higher catalytic activity than polyoxotungstate-based compounds 1-2 with 99%DPM conversion and 99%benzophenone(BP)selectivity within 6 h as well as good recyclability and structural stability.展开更多
Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by ...Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.展开更多
High costs and low catalytic efficiency of metalloporphyrins, which are an analogue of cytochrome P450 enzyme, are the bot-tlenecks in the industrialization of biomimetic hydrocarbon oxidation reactions. The basic pri...High costs and low catalytic efficiency of metalloporphyrins, which are an analogue of cytochrome P450 enzyme, are the bot-tlenecks in the industrialization of biomimetic hydrocarbon oxidation reactions. The basic principle and research technique of physical organic chemistry were applied to the process of biomimetic oxidation of hydrocarbon catalyzed by metalloporphyrins. This biomimetic technology could be adapted to bulk chemicals production by developing the new methods for efficient scale-up synthesis of metalloporphyrins, new pathways for molecular oxygen activation on an industrial scale and new approaches to elevate the catalytic efficiency of metalloporphyrins. This review mainly focuses on research carried out in our group.展开更多
Using 2,3-dichloro-5,6-dicyano-p-benzoquinone(DDQ)as the oxidant,we communicate an efficient oxidative C–N coupling of benzylic C–H bonds with amides to afford a series of amination products in good yields.A wide ra...Using 2,3-dichloro-5,6-dicyano-p-benzoquinone(DDQ)as the oxidant,we communicate an efficient oxidative C–N coupling of benzylic C–H bonds with amides to afford a series of amination products in good yields.A wide range of functional groups as well as various sulfonamides and carboxamides are well tolerated.Moreover,this reaction involves both the challenging C–H functionalization and C–N bond formation.展开更多
The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules.In...The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules.In this work,two transition metal-containing Nb/W mixed-addendum POMs dimers with the formula of K_(2)Na_(2)H_(5)[(Fe(H_(2)O)_(4))_(3)(P_(2)W_(15)Nb_(3)O_(62))_(2)]·24H_(2)O(POM[Fe])and K_(2)Na_(3)H_(4)[(Cr(H_(2)O)_(4))_(3)(P_(2)W_(15)Nb_(3)O_(62))_(2)]·32H_(2)O(POM[Cr])have been synthesized and characterized by various analytical and spectral techniques.POM[Fe]was proved to be an efficient photocatalyst for benzylic C–H oxidation under visible light and using oxygen as an oxidant to produce the corresponding carbonyl complex in good yields.A plausible mechanism involving superoxide radical was proposed for the catalytic reaction.POM[Fe]showed good reusability in the recycling experiments.IR spectroscopy and XRD analysis indicate that POM[Fe]can retain its integrity after catalysis.展开更多
基金supported by the National Basic research Program of China (973 Program,2009CB623505)the National Natural Science Foundation of China (21273225)~~
文摘Novel reusable MnOx‐N@C catalyst has been developed for the direct oxidation of N‐heterocycles under solvent‐free conditions using TBHP as benign oxidant to give the corresponding N‐heterocyclic ketones. The catalytic system exhibited a broad substrate scope and excellent regi‐oselectivity, as well as being amenable to gram‐scale synthesis. This MnOx‐N@C catalyst also showed good reusability and was successfully recycled six times without any significant loss of activity.
文摘Here,we demonstrate a photochemical strategy to site-specifically deposit Pd atoms on Au nanoparticles.The high-sensitivity low-energy ion scattering spectra combined with the X-ray photoelectron spectra reveal that the surface electronic structure of Pd can be continuously regulated by tailoring the Pd-to-Au molar ratio and the location of Pd atoms in Au Pd nanoparticles.It is revealed that electron-rich Pd atoms are considerably more active than the net Pd atoms in aerobic alcohol oxidation.Remarkably,the catalyst with the most electron-rich Pd sites(binding energy downshift:1.0 e V)exhibits an extremely high turnover frequency(~500000 h-1 vs 12000 h-1 for that with net Pd atoms)for solvent-free selective oxidation of benzyl alcohol,which is,to the best of our knowledge,the highest value ever reported.Kinetic studies reveal that electron-rich Pd atoms can accelerate the oxidation of benzyl alcohol by facilitating C-H cleavage,as indicated by the significant reduction in the activation energy as compared to net Pd atoms.
基金This work was supported by the National Natural Science Foundation of China （No.20971058） and the Fundamental Research Funds for the Central Universities （No.JUSRPIII05）.
文摘We examined the puzzling mechanism for Cu-catalyzed meta-C-H arylation reaction of anilides by diaryliodonium salts through systematic theoretical analysis. The previously proposed anti-oxy-cupration mechanism featuring anti-1,2- or anti-1,4-addition of cuprate and oxygen to the phenyl ring generating a meta-cuprated intermediate was excluded due to the large activation barriers. Alternatively, a new amide-directed carbocupration mechanism was proposed which involves a critical rate- and regio-determining step of amide-directed addition of the Cu（III）-aryl bond across the phenyl C2=C3 double bond to form an orthocuprated, meta-arylated intermediate. This mechanism is kinetically the most favored among several possible mechanisms such as ortho-or para-cupration/migration mechanism, direct meta C-H bond cleavage mediated by Cu（III） or Cu（I）, and Cu（III）-catalyzed ortho-directed C-H bond activation mechanism this mechanism has been shown to Furthermore, the predicted regioselectivity based on favor the meta-arylation that is consistent with the experimental observations.
基金financial support from the National Natural Science Foundation of China (grant no.22201121)Jiangxi Provincial Natural Science Foundation (grant nos.20224BAB213006 and 20232BAB203002).
文摘The site-selective C-H fluorination of heteroarenes is a straightforward approach to accessing valuable heteroaryl fluorides but remains a formidable challenge.Herein,we report a general strategy for visible-light-induced C-H fluorination of heteroarenes via the merger of N-F fluorinating reagents and silane.Electron paramagnetic resonance experiments provide evidence for the homolytic cleavage of the N-F bond under blue light-emitting diode irradiation,which is the key step in the process.This transformation is metal-free,photocatalysts-free,and site-selective under mild reaction conditions(ambient temperature,visible-light irradiation,tolerant to H2O).The robustness of this protocol has also been highlighted by late-stage modification of complex and medicinally relevant molecules.
基金supported by National Natural Science Foundation of China(Grants 21901060,21871076)Natural Science Foundation of Hebei Province(Grants B2022205005,B2019205074,B2020205008 and B2016205051)+3 种基金Science and Technology Project of Hebei Education Department(Grants BJ2020037 and QN2023049)the China Postdoctoral Science Foundation funded project(No.2021TQ0095)Science Foundation of Hebei Normal University(L2019B15)the Innovation Capability Improvement Plan Project of Hebei Province(22567604H).
文摘Exploring new heterogeneous catalysts to achieve efficient C-H bond oxidation is momentous in industrial chemical production.Herein,three Fe-incorporated polyoxometalate-encapsulated metal-organic frameworks(POM@MOFs),[Fe(H_(2)O)_(3)(dtb)][Fe(dtb)_(2)][HBW_(12)O_(40)]-12H_(2)O(1),[Fe(H_(2)O)2(dtb)]_(2)[Fe(dtb)_(2)(Hdtb)][SiW^(Ⅵ)_(9)W^(Ⅴ)_(3)O_(40)]·16H_(2)O(2),[Fe(H_(2)O)_(2)]_(4)(dtb)_(5)[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]_(2)·18H_(2)O(3),(dtb=1,4-di[4H-1,2,4-triazol-4-yl]-benzene),were hydrothermally synthesized for catalytic C-H bond oxidation.They exhibited three-dimensional(3-D)POM-based metal-organic host-guest frameworks with diverse cages.In compound 1,cationic metal-organic frameworks constructed by binuclear[Fe_(2)(dtb)_(6)(H_(2)O)_(2)]^(4+)clusters and dtb ligands present a pcu alpha-Po primitive cubic topological net and abundant twisted quadrangular prism-shaped cages,in which the monoprotonated[HBW_(12)O_(40)]^(4-)polyoxoanions are encapsulated.In compound 2,two-dimensional(2-D)cationic metal-organic layers constructed by trinuclear[Fe_(3)(dtb)_(6)(H_(2)O)_(4)]^(6+)clusters and dtb ligands display a sql/Shubnikov tetragonal plane net topology,in which the rhomboid-shaped metal-organic windows in adjacent parallel-arranged 2-D layers are enclosed to form an open parallelepiped cage.The[SiW^(Ⅵ)_(9)W^(Ⅴ)_(3)O_(40)]^(7-)poly-oxoanions locate in the parallelepiped cages between 2-D bilayers.In compound 3,the 3-D cationic metal-organic frameworks constructed by binuclear[Fe_(2)(dtb)_(3)(H_(2)O)_(4)]^(4+)clusters and dtb ligands possess a bnn hexagonal BN topology,in which the hexagonal prismatic metal-organic cages accommodate four[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]^(4-)poly-oxoanions.Employing diphenylmethane(DPM)oxidation as C-H bond oxidation model reaction,compounds 1-3 displayed distinct catalytic activities owing to the synergistic effect of polynuclear Fe nodes and poly-oxoanions.Among them,[PMo^(Ⅵ)_(11)Mo^(Ⅴ)O_(40)]^(4-)-contained compound 3 exhibited higher catalytic activity than polyoxotungstate-based compounds 1-2 with 99%DPM conversion and 99%benzophenone(BP)selectivity within 6 h as well as good recyclability and structural stability.
基金Financial support by the National Natural Science Foundation of China (Grant Nos. 20433030, 20625310, 20773099 and 20873110)the National Basic Program of China (Grant Nos. 2005CB221408 and 2010CB732303)+1 种基金the Key Scientific Project of Fujian Province (2009HZ0002-1)the Program for New Century Excellent Talents in Fujian Province (to Q. Z.)
文摘Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.
基金supported by the National Natural Science Foundation of China (0142003, 20376018, 2890047, 29372047 , 2950041)National High-Tech Research & Development Program of China (863 Program, 2002AA321070 and 2006AA32Z467)National Key Technologies R & D Program of China (2004BA322B)
文摘High costs and low catalytic efficiency of metalloporphyrins, which are an analogue of cytochrome P450 enzyme, are the bot-tlenecks in the industrialization of biomimetic hydrocarbon oxidation reactions. The basic principle and research technique of physical organic chemistry were applied to the process of biomimetic oxidation of hydrocarbon catalyzed by metalloporphyrins. This biomimetic technology could be adapted to bulk chemicals production by developing the new methods for efficient scale-up synthesis of metalloporphyrins, new pathways for molecular oxygen activation on an industrial scale and new approaches to elevate the catalytic efficiency of metalloporphyrins. This review mainly focuses on research carried out in our group.
基金supported by the National Basic Research Program of China(2011CB808600,2012CB725302)the National Natural Science Foundation of China(21390400,21272180,21302148)+2 种基金the Research Fund for the Doctoral Program of Higher Education of China(20120141130002)the Program for Changjiang Scholars and Innovative Research Team in University(IRT1030)The Program of Introducing Talents of Discipline to Universities of China(111 Program)is also appreciated
文摘Using 2,3-dichloro-5,6-dicyano-p-benzoquinone(DDQ)as the oxidant,we communicate an efficient oxidative C–N coupling of benzylic C–H bonds with amides to afford a series of amination products in good yields.A wide range of functional groups as well as various sulfonamides and carboxamides are well tolerated.Moreover,this reaction involves both the challenging C–H functionalization and C–N bond formation.
基金supported by the National Natural Science Foundation of China(Nos.22171073.21971224 and U1804253)the Natural Science Foundation of Henan Province(No.202300410246).
文摘The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules.In this work,two transition metal-containing Nb/W mixed-addendum POMs dimers with the formula of K_(2)Na_(2)H_(5)[(Fe(H_(2)O)_(4))_(3)(P_(2)W_(15)Nb_(3)O_(62))_(2)]·24H_(2)O(POM[Fe])and K_(2)Na_(3)H_(4)[(Cr(H_(2)O)_(4))_(3)(P_(2)W_(15)Nb_(3)O_(62))_(2)]·32H_(2)O(POM[Cr])have been synthesized and characterized by various analytical and spectral techniques.POM[Fe]was proved to be an efficient photocatalyst for benzylic C–H oxidation under visible light and using oxygen as an oxidant to produce the corresponding carbonyl complex in good yields.A plausible mechanism involving superoxide radical was proposed for the catalytic reaction.POM[Fe]showed good reusability in the recycling experiments.IR spectroscopy and XRD analysis indicate that POM[Fe]can retain its integrity after catalysis.
