Recent progress of carbon-based metal-free materials in thermal-driven catalysis

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.

Stereoselective Syntheses of Some β-D-1-Thioglycopyranosides and Bis(β-D-glycopyranosyl) Sulfides by Phase Transition Catalysis

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.

Catalysis of Active Carbon Supporting Transition Metal Oxides for Pyrotechnical Reagent with Potassium Perchlorate

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.

Synthesis of 1,2:4,5-di-O-Isopropylidene-3-C-Cyano-β-D-ribo-hex-2-ulo Pyranose by Phase Transition Catalysis

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-

Reductive Deoxygenative Functionalization of Alcohols by First-Row Transition Metal Catalysis

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.

Probing the intrinsic catalytic activity of carbon nanotubes for the metal-free oxidation of aromatic thiophene compounds in ionic liquids

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.

The highly selective catalytic hydrogenation of CO_(2)to CO over transition metal nitrides

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.

The Activation and Carbonylation of the C-Cl Bond Catalyzed by Transition-Metal Complexes

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%.

Metal-Free Photocatalytic[4+2]Annulation of Acrylamides with 2-Benzyl-2-bromocarbonyls to Assemble Tetralin-1-carboxamides

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.

苯磺酸锰配合物的制备及其催化Mannich反应性能研究

以氯化锰与苯磺酸钠为原料,通过加热合成了苯磺酸锰,进一步将溶剂挥发,得到了苯磺酸锰配合物.通过单晶X-射线衍射技术测定了晶体结构,分子式为:[Mn(H_(2)O)_(6)](C_(6)H_(5)SO_(3))2.粉末X-射线衍射证明目标产物具有较高的相纯度.红外光谱法验证了目标产物的分子结构.热重分析方法表明目标产物的热稳定性较好,在510℃前未分解.实验使用Mannich反应作为探针,考察了苯磺酸锰配合物的催化性能,结果表明,该配合物在催化Mannich反应时,用量少,效率高,重复使用三次仍保持催化活性,苯磺酸锰配合物催化性能良好.

基于二维过渡金属硫化物的催化传感的研究进展

二维过渡金属硫化物是一种新兴材料,具备多种独特的性能,如最大静电效率、优越的机械强度、可调谐的电子结构、优秀的光学透明度和传感器灵敏度,被认为是潜在的、无处不在的电子、能源和传感器设备。本文综述了二维过渡金属硫化物在电化学传感器、光化学传感器、生物传感器领域的应用及研究进展,阐述了通过设计和调控金属硫化物能带位置和进行原子掺杂等,优化其催化活性,使其具有更优异的灵敏度,从而扩展其应用领域。同时讨论了表面增强拉曼(SERS)技术与现在热门的纳米酶催化技术联用的发展现状及优势。最后,展望了二维过渡金属硫化物在传感器技术面临的挑战和发展前景。

过渡金属催化羰基化反应的最新研究进展

过渡金属催化羰基化反应是制备羰基化合物最直接的方法之一,近年来得到了迅速的发展.利用活性高且廉价的CO气体作羰基源,通过过渡金属催化的方法实现羰基化,是现代有机合成中构建含羰基化合物的有效方法.基于反应原料和产品氧化还原价态的改变等不同方式,将过渡金属催化羰基化反应分为四种主要类型:杂核亲核试剂的羰基化反应,碳亲核试剂的羰基化反应,碳亲电试剂的羰基化反应和还原偶联的羰基化反应,分别综述了各类型羰基化反应的最新研究进展.

基于烯烃碳-氢键活化的碳-碳交叉偶联反应

烯烃是一类非常重要的化合物,人们可以由烯烃通过一系列转化得到复杂的有机分子。本文主要对基于烯烃碳-氢键活化的碳-碳交叉偶联反应进行了详细介绍,基于烯烃的碳-氢键活化,利用铑、钯、钴等过渡金属催化剂,通过碳-碳交叉偶联反应,构建各类碳-碳键。对于烯烃碳-氢键活化反应的介绍,能够丰富和拓展有机化学课程中烯烃的知识点,帮助学生了解有机化学的发展前沿,提高学生学习的积极性和主动性,培养学生的科研素养。

CO_(2)热催化加氢合成甲醇催化剂的研究进展

CO_(2)作为原料制备甲醇是一种极具前景的碳减排技术,但其工业化仍面临许多挑战。CO_(2)具有很强的化学惰性,在反应过程需要利用活性金属使催化剂具备较强的活化CO_(2)的能力以及适宜的加氢性能。本文致力于介绍目前CO_(2)热催化转化为甲醇的反应机理,总结了CO_(2)热催化加氢制备甲醇的过渡金属基、贵金属基催化剂的研究进展,并对未来研究方向进行了展望。

2-(甲氧基亚胺基)苯乙酸的合成研究

研究了2-(甲氧基亚胺基)苯乙酸即苯基MIA的合成,并对该工艺的反应条件进行了筛选和优化。将甲氧基胺基盐酸盐和碳酸钠固体分别加入圆底烧瓶中,溶于干燥的二氯甲烷,0℃下加入苯甲酰甲酸,25℃下反应3h。该工艺方法得到72%左右的收率,且反应条件简单温和,工艺设备成本廉价,实现了操作简单、经济实惠和绿色环保的目的。

Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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.

Combinations of electron and proton donors in transition-metal complex mediated nitrogen reduction reactions

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.

EDA复合物介导的光催化合成全氟取代异喹啉二酮

本文开发了一个由电子供体受体(EDA)复合物介导、可见光诱导合成全氟取代异喹啉二酮骨架的反应。该反应无需过渡金属光敏剂催化,反应条件温和,具有绿色环保、清洁高效的特点。

二氧化碳转化为氨基甲酸酯的研究进展

二氧化碳(CO_(2))是大气中主要的温室气体,同时也是一种丰富、无毒和可再生的碳一资源。因此,将CO_(2)转化为有价值的化学品对实现可持续发展具有重要意义。然而,由于CO_(2)的热力学稳定性和动力学惰性,其活化转化非常具有挑战性。氨基甲酸酯是一类具有生物活性的重要化合物,广泛存在于天然产物、农用化学品和医药相关分子中,同时也是重要的有机合成中间体。近年来,利用CO_(2)作为光气的替代品用于合成氨基甲酸酯吸引了广泛的关注。本文主要综述了CO_(2)和胺在不同的催化体系下合成氨基甲酸酯的最新研究进展,主要分为无过渡金属催化、过渡金属催化、电催化、光催化四种反应体系来归纳总结,并对CO_(2)转化为氨基甲酸酯的未来研究方向进行了展望。

Mechanism of K/Ni Etching for Biochar-H_(2)O Gasification

Biomass-H_(2)O gasification is a complex thermochemical reaction,including three processes of volatile removal:homogeneous/heterogeneous reforming,biochar gasification and etching.The rate-determining step is biochar-H_(2)O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni)in the zigzag biochar model.The calculation results show that the gasification of biochar-H_(2)O needs to go through four processes:dissociative adsorption of water,hydrogen transfer(hydrogen desorption,hydrogen atom transfer),carbon dissolution and CO desorption.The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step,which is reduced from 374.14 kJ/mol to 152.41 kJ/mol;the catalytic effect of Ni is mainly reflected in the carbon dissolution step,which is reduced from 122.34 kJ/mol to 84.8 kJ/mol.The existence of K causes the edge to have a stronger attraction to H and does not destroy theπbonds of biochar molecules.The destruction ofπbonds is mainly due to the role of H free radicals,while the destruction ofπbonds will lead to easier C-C bond rupture.Ni shows a strong attraction to O in OH,which forms strong Ni-O chemical bonds.Ni can also destroy the aromatic structure directly,making the gasification easier to happen.This study explored the catalytic mechanism of K/Ni on the biochar-H_(2)O gasification at the molecular level and looked forward to the potential synergy of K/Ni,laying a foundation for experimental research and catalyst design.