The carbon-based metal-free materials as catalysts(named as carbocatalysts) have been attracting tremendous attentions in electric-,solar-and thermal-driven reactions nowadays.Compared to electrocatalysis and photocat...The carbon-based metal-free materials as catalysts(named as carbocatalysts) have been attracting tremendous attentions in electric-,solar-and thermal-driven reactions nowadays.Compared to electrocatalysis and photocatalysis,the thermal-driven catalysis(thermocatalysis) including liquid phase and gas phase reactions involves wider scope and is relatively easy to realize practical large-scale applications.Over the past several years,some striking achievements on the design of new carbon-based metal-free materials with well-defined structures and heteroatom groups as well as the revelation of new reaction mechanisms and active sites in thermocatalysis have been obtained.However,comparative discussions regarding these recent achievements have been rarely highlighted.In this review,we systematically summarize and discuss six kinds of carbocatalysts and their applications in thermocatalysis.These materials include typical oxygen-attached carbon,surface modified carbon(graft with certain organic compounds),mono-doped carbon,co-doped carbon,carbon nitride and materials with carbon as dopant.Some new reaction processes as well as the related reaction mechanisms,active sites and intermediates are reviewed critically.Moreover,an outlook on the in-depth investigation of the metalfree carbocatalysis in the future is provided.展开更多
The present paper covers the stereoselective syntheses of four 1 thiogalactopyranosides 1—4 and three thio disaccharides 5—7 through the PTC methods and their structures confirmed by means of elementary analysis, ...The present paper covers the stereoselective syntheses of four 1 thiogalactopyranosides 1—4 and three thio disaccharides 5—7 through the PTC methods and their structures confirmed by means of elementary analysis, IR and NMR spectral data.展开更多
In order to improve the pyrotechnical reagent with potassium perchlorate,composite catalyst of active carbon supporting transition metal oxides (TMO),Fe2O3 and CuO,were prepared and added into pyrotechnical reagent ...In order to improve the pyrotechnical reagent with potassium perchlorate,composite catalyst of active carbon supporting transition metal oxides (TMO),Fe2O3 and CuO,were prepared and added into pyrotechnical reagent with potassium perchlorate.Accelerating rate calorimeter (ARC) was used to study the catalysis of pyrotechnical reagent which is consisted of potassium perchlorate and composite catalyst.Composite catalyst of both Fe2O3 and CuO supported by active carbon can catalyze pyrotechnical reagent with potassium perchlorate.Furthermore,it can lower the apparent activation energy and accelerate the reaction with a smaller quantity than that with Fe2O3 and CuO.The maximal reaction rate of pyrotechnical reagent with potassium perchlorate mixed with Fe2O3/active carbon and CuO/active carbon is 8.31 min-1 and 9.13 min-1,which is 1.74 times and 1.91 times of pyrotechnical reagent mixed with no catalyst;time to maximal rate was 18.99 min and 1.96 min respectively,which is lower than pyrotechnical reagent mixed with no catalyst by 86.46% and 98.67% ;the apparent activation energy is 368.10 kJ·mol-1 and 325.29 kJ·mol-1,which is lower than pyrotechnical reagent mixed with no catalyst by 31.89% and 39.81% respectively.展开更多
Introduction The cyano branched carbohydrates are useful, versatil intermediaries for the synthesis of branched sugars having biological activity in nature. Owing to the good yield, mild reaction conditions and high s...Introduction The cyano branched carbohydrates are useful, versatil intermediaries for the synthesis of branched sugars having biological activity in nature. Owing to the good yield, mild reaction conditions and high stereospecificity, the phase transition catalysis(PTC)method has been widely used to the syntheses of C-展开更多
Alcohols are among the most accessible functionalities.Catalytic deoxygenative functionalization of alcohols is highly synthetically appealing.While significant progress has been made on the reactions with nucleophile...Alcohols are among the most accessible functionalities.Catalytic deoxygenative functionalization of alcohols is highly synthetically appealing.While significant progress has been made on the reactions with nucleophiles,the reactions with electrophilic coupling partners remain a real challenge.This manuscript highlights the advance in this direction,which is mainly achieved by the first-row transition metals.The low-valent titanium catalyst has shown the unique reactivity to homolytically cleave the C—OH bonds.The formed carbon radicals could either undergo reduction to give protonation products or couple with carbon fragments to form C—C bonds.This chemistry is initially realized using a stoichiometric amount of titanium reagents and later extended to catalytic variants.Nickel features a variety of oxidation states ranging from Ni0 to NiIV,and both two-electron oxidative addition and single-electron process are involved in their activation of an electrophile.These properties enable nickel to catalyze reductive C—C coupling of alcohols with R–X electrophiles.The reaction is first reported on the reactions of allylic alcohols,then extended to benzylic alcohols and,very recently non-activated alcohols.Recent effort has resulted in many invaluable methodologies that highly improve the reaction efficiency for the construction of aliphatic C—C bonds.The use of cobalt and copper catalysts not only expands the substrate scope of these reactions but also shows the new reactivity and selectivity issues.展开更多
A metal-free catalytic system combining oxidized carbon nanotubes (oCNTs) and ionic liquids (ILs) is presented for the oxidation of aromatic thiophene compounds with H2O2 as an oxidant. The oCNTs exhibit impressively ...A metal-free catalytic system combining oxidized carbon nanotubes (oCNTs) and ionic liquids (ILs) is presented for the oxidation of aromatic thiophene compounds with H2O2 as an oxidant. The oCNTs exhibit impressively high activity and stability in the system, which show an even better performance than those of some reported metal catalysts. The ILs are proved to have indispensable influence on the enhanced catalytic performance of the oCNTs. Detailed characterization by TG-MS and XPS demonstrates that the carbonyl groups are the active sites for the oxidation process, which is further supported by the deactivation and the model catalysts experiments. The quantitative analysis of different oxygen groups in oCNTs could be achieved by an isothermal temperature programmed TG-MS method. The concentration of carbonyl groups is 1.46 mmol per 1 g oCNTs and the tuiriover frequency of oCNTs could also be obtained (10.7 h^-1 in the presence of OmimPF6). H2O2 decomposition experiments combined with the EPR results reveal that the presence of OmimPF6 can avoid the intermediate HO· to form O2 and then improve the catalytic performance of oCNTs for the oxidation of dibenzothiophene.展开更多
Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride cat...Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600℃,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400℃,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway.展开更多
Diethyl malonate was synthesized by transition-metal catalyzed alkoxycarbonylation of ethyl chloroacetate. The results show that the conversion of ethyl chloroacetate is greater than 92%, and the selectivity to diethy...Diethyl malonate was synthesized by transition-metal catalyzed alkoxycarbonylation of ethyl chloroacetate. The results show that the conversion of ethyl chloroacetate is greater than 92%, and the selectivity to diethyl malonate is 67.5%.展开更多
Tetralin-1-carboxamides are frequently incorporated in myriad medicinally important molecules.However,their existing synthetic routes not only suffer from some drawbacks such as tedious procedures,harsh reaction condi...Tetralin-1-carboxamides are frequently incorporated in myriad medicinally important molecules.However,their existing synthetic routes not only suffer from some drawbacks such as tedious procedures,harsh reaction conditions,narrow substrate scope,low yields,and environmental problems,but are also based upon the elaboration of uneasily available non-linear tetralin derivatives.Herein,we describe a metal-and additive-free visible light-induced[4+2]annulation of two simple linear starting materials,namely acrylamides and 2-benzyl-2-bromocarbonyls,through a cascade C(sp^(3))-Br/C(sp^(2))-H bond cleavage,double C-C bond formation,and aromatization sequence.The developed protocol provides a convenient,efficient,and green approach to a variety of tetralin-1-carboxamide derivatives with good functional group compatibility.Importantly,the resulting products could also undergo the Licl-mediated mono-decarboxylative cyclization process to further furnish the architecturally novel bridged polycyclic imides with excellentcis-diastereoselectivities.展开更多
1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in s...1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.展开更多
Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to re...Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with silanes.As the synthesis of diverse catalytic progress,the categories of donors have seen rapid expansion.However,existing literature only provides summaries regarding the metal,ligands,and mechanism.Despite the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this aspect.Therefore,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor combinations.This review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related catalysts.Finally,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.展开更多
基金supported by the Award Program for Fujian Minjiang Scholar Professorship,the National Natural Science Foundation of China(21571035)Chemical Engineering&Technology of Zhejiang Province First-Class Discipline(Taizhou University),Zhejiang Provincial Natural Science Foundation of China(LQ20B060001)Taizhou science and technology planning project(1902gy20)。
文摘The carbon-based metal-free materials as catalysts(named as carbocatalysts) have been attracting tremendous attentions in electric-,solar-and thermal-driven reactions nowadays.Compared to electrocatalysis and photocatalysis,the thermal-driven catalysis(thermocatalysis) including liquid phase and gas phase reactions involves wider scope and is relatively easy to realize practical large-scale applications.Over the past several years,some striking achievements on the design of new carbon-based metal-free materials with well-defined structures and heteroatom groups as well as the revelation of new reaction mechanisms and active sites in thermocatalysis have been obtained.However,comparative discussions regarding these recent achievements have been rarely highlighted.In this review,we systematically summarize and discuss six kinds of carbocatalysts and their applications in thermocatalysis.These materials include typical oxygen-attached carbon,surface modified carbon(graft with certain organic compounds),mono-doped carbon,co-doped carbon,carbon nitride and materials with carbon as dopant.Some new reaction processes as well as the related reaction mechanisms,active sites and intermediates are reviewed critically.Moreover,an outlook on the in-depth investigation of the metalfree carbocatalysis in the future is provided.
文摘The present paper covers the stereoselective syntheses of four 1 thiogalactopyranosides 1—4 and three thio disaccharides 5—7 through the PTC methods and their structures confirmed by means of elementary analysis, IR and NMR spectral data.
基金Sponsored by the National Natural Science Foundation of China(50874017)
文摘In order to improve the pyrotechnical reagent with potassium perchlorate,composite catalyst of active carbon supporting transition metal oxides (TMO),Fe2O3 and CuO,were prepared and added into pyrotechnical reagent with potassium perchlorate.Accelerating rate calorimeter (ARC) was used to study the catalysis of pyrotechnical reagent which is consisted of potassium perchlorate and composite catalyst.Composite catalyst of both Fe2O3 and CuO supported by active carbon can catalyze pyrotechnical reagent with potassium perchlorate.Furthermore,it can lower the apparent activation energy and accelerate the reaction with a smaller quantity than that with Fe2O3 and CuO.The maximal reaction rate of pyrotechnical reagent with potassium perchlorate mixed with Fe2O3/active carbon and CuO/active carbon is 8.31 min-1 and 9.13 min-1,which is 1.74 times and 1.91 times of pyrotechnical reagent mixed with no catalyst;time to maximal rate was 18.99 min and 1.96 min respectively,which is lower than pyrotechnical reagent mixed with no catalyst by 86.46% and 98.67% ;the apparent activation energy is 368.10 kJ·mol-1 and 325.29 kJ·mol-1,which is lower than pyrotechnical reagent mixed with no catalyst by 31.89% and 39.81% respectively.
基金Supported by the National Natural Science Foundation of China
文摘Introduction The cyano branched carbohydrates are useful, versatil intermediaries for the synthesis of branched sugars having biological activity in nature. Owing to the good yield, mild reaction conditions and high stereospecificity, the phase transition catalysis(PTC)method has been widely used to the syntheses of C-
基金National Natural Science Foundation of China for its financial support(22271127,22071084)The financial support by the Fundamental Research Funds for the Central Universities(lzujbky-2022-ey01)is acknowledged.
文摘Alcohols are among the most accessible functionalities.Catalytic deoxygenative functionalization of alcohols is highly synthetically appealing.While significant progress has been made on the reactions with nucleophiles,the reactions with electrophilic coupling partners remain a real challenge.This manuscript highlights the advance in this direction,which is mainly achieved by the first-row transition metals.The low-valent titanium catalyst has shown the unique reactivity to homolytically cleave the C—OH bonds.The formed carbon radicals could either undergo reduction to give protonation products or couple with carbon fragments to form C—C bonds.This chemistry is initially realized using a stoichiometric amount of titanium reagents and later extended to catalytic variants.Nickel features a variety of oxidation states ranging from Ni0 to NiIV,and both two-electron oxidative addition and single-electron process are involved in their activation of an electrophile.These properties enable nickel to catalyze reductive C—C coupling of alcohols with R–X electrophiles.The reaction is first reported on the reactions of allylic alcohols,then extended to benzylic alcohols and,very recently non-activated alcohols.Recent effort has resulted in many invaluable methodologies that highly improve the reaction efficiency for the construction of aliphatic C—C bonds.The use of cobalt and copper catalysts not only expands the substrate scope of these reactions but also shows the new reactivity and selectivity issues.
基金provided by the National Natural Science Foundation of China(No.21503241,21133010,21261160487,51221264,21411130120,21473223,91545119,91545110)the“Strategic Priority Research Program” of the Chinese Academy of Sciences(CAS)(No.XDA09030103)+1 种基金CAS/State Administration for Foreign Experts Affairs(SAFEA)International Partnership Program for Creative Research Teams and the Doctoral Starting up Foundation of Liaoning Province,China(No.20121068)the financial support from Max Planck Society and China Scholarship Council
文摘A metal-free catalytic system combining oxidized carbon nanotubes (oCNTs) and ionic liquids (ILs) is presented for the oxidation of aromatic thiophene compounds with H2O2 as an oxidant. The oCNTs exhibit impressively high activity and stability in the system, which show an even better performance than those of some reported metal catalysts. The ILs are proved to have indispensable influence on the enhanced catalytic performance of the oCNTs. Detailed characterization by TG-MS and XPS demonstrates that the carbonyl groups are the active sites for the oxidation process, which is further supported by the deactivation and the model catalysts experiments. The quantitative analysis of different oxygen groups in oCNTs could be achieved by an isothermal temperature programmed TG-MS method. The concentration of carbonyl groups is 1.46 mmol per 1 g oCNTs and the tuiriover frequency of oCNTs could also be obtained (10.7 h^-1 in the presence of OmimPF6). H2O2 decomposition experiments combined with the EPR results reveal that the presence of OmimPF6 can avoid the intermediate HO· to form O2 and then improve the catalytic performance of oCNTs for the oxidation of dibenzothiophene.
基金financially supported by the National Natural Science Foundation of China(22002140)Zhejiang Provincial Natural Science Foundation of China(LR21B030001 and LR22b030003)+1 种基金Young Elite Scientist Sponsorship Program by CAST(No.2019QNRC001)Use of the Advanced Photon Source(beamlines 17-BM,for in-situ XRD characterization)was supported by the U.S.DOE under contract no.DE-AC02-06CH11357。
文摘Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600℃,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400℃,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway.
文摘Diethyl malonate was synthesized by transition-metal catalyzed alkoxycarbonylation of ethyl chloroacetate. The results show that the conversion of ethyl chloroacetate is greater than 92%, and the selectivity to diethyl malonate is 67.5%.
基金supported by the National Natural Science Foundation of China(Nos.22101237,22171233)the Science and Technology Program of Sichuan Province(Nos.2022YFS0608,2022NSFSC1219)+1 种基金the Open Project Program of Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province(Nos.HYX21003,HYX22008)the research fund of Southwest Medical University(2021ZKMS042).
文摘Tetralin-1-carboxamides are frequently incorporated in myriad medicinally important molecules.However,their existing synthetic routes not only suffer from some drawbacks such as tedious procedures,harsh reaction conditions,narrow substrate scope,low yields,and environmental problems,but are also based upon the elaboration of uneasily available non-linear tetralin derivatives.Herein,we describe a metal-and additive-free visible light-induced[4+2]annulation of two simple linear starting materials,namely acrylamides and 2-benzyl-2-bromocarbonyls,through a cascade C(sp^(3))-Br/C(sp^(2))-H bond cleavage,double C-C bond formation,and aromatization sequence.The developed protocol provides a convenient,efficient,and green approach to a variety of tetralin-1-carboxamide derivatives with good functional group compatibility.Importantly,the resulting products could also undergo the Licl-mediated mono-decarboxylative cyclization process to further furnish the architecturally novel bridged polycyclic imides with excellentcis-diastereoselectivities.
基金supported by the National Natural Science Foundation of China (22071111)the Jiangsu Specially Appointed Professor Plan+1 种基金the Natural Science Foundation of Jiangsu Province(BK20201368, BK20220409)the Postgraduate Research&Practice Innovation Program of Jiangsu Province (KYCX23_1683)。
文摘1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.
基金supported by the King Abdullah University of Science and Technologysupported by Agency for Science,Technology,and Research(SC22/23-82301U,SC22/23-82801U)。
文摘Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with silanes.As the synthesis of diverse catalytic progress,the categories of donors have seen rapid expansion.However,existing literature only provides summaries regarding the metal,ligands,and mechanism.Despite the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this aspect.Therefore,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor combinations.This review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related catalysts.Finally,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.