检索结果-南通市图书馆

Radical Arbuzov Reaction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CCS chemistry 2024年第5期6卷 1312-1323页

作者： Linxiang Chai Jian Wang Jimin Yang Junyue Yin Zhuyong Zhang Yulu Cheng Lin Zhu Xiao-Song Xue Chaozhong Li Department of chemistry University of Science and Technology of ChinaHefeiAnhui 230026 Shanghai institute of Organic chemistry Chinese Academy of SciencesShanghai 200032

The Arbuzov reaction(also known as the Michaelis–Arbuzov reaction)is one of the most fundamental transformations in organic chemistry and has been extensively used for the synthesis of organophosphorus compounds for over a century.However,the reaction generally requires an elevated temperature and is applicable mainly to primary alkyl halides with poor functional group tolerance.We report herein a radical alternative to the conventional nucleophilic substitution reaction.Thus,new radical phosphonylation reagents,9-fluorenyl o-phenylene phosphite and benzhydryl o-phenylene phosphite,have been developed for this purpose.The photoredox-catalyzed reaction of a wide range of alkyl bromides or iodides with 9-fluorenyl(or benzhydryl)o-phenylene phosphite followed by workup with methanol(or ethanol)provides the corresponding dimethyl(or diethyl)alkylphosphonates in satisfactory yields at room temperature under mild conditions.The method is applicable to primary,secondary,and even tertiary alkyl iodides and bromides and exhibits an excellent functional group tolerance,thereby enabling the late-stage modification of complex molecules and rapid synthesis of phosphonate-containing natural products and drug molecules.A mechanism involving the formation and subsequentβ-scission of phosphoranyl radicals is proposed.

关键词： Arbuzov reaction radicals phosphonylation photoredox catalysis alkyl halides

Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China chemistry 2024年第2期67卷 536-541页

作者： Yong Wang Qiaoqiao Zhang Yong-Yong Cao Qi Liu Brendan F.Abrahams Jian-Ping Lang College of chemistry Chemical Engineering and MaterialsSoochow UniversitySuzhou215123China State Key Laboratory of Organometallic chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai200032China College of Biological Chemical Science and EngineeringJiaxing UniversityJiaxing314001China School of chemistry University of MelbourneVictoria3010Australia

In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are uncommon.Herein,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,CP1a.It is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few minutes.The transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction conditions.Density functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product CP1b.This work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and stimuli.The insights gained from this work also assist in the design of fast,reversible switching materials.

关键词： asymmetrical reversible structural switching coordination polymer photocycloaddition UV-visible light-controlled fluorescence switching

Iron-Catalyzed Reductive C(aryl)—Si Cross-Coupling of Diaryl Ethers with Chlorosilanes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of chemistry 2024年第6期42卷 578-584页

作者： Pei Liu Baowei Wu Xuefeng Cong Jie Kong School of chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi'anShaanxi710072 China institute of Molecular Plus Department of Chemistry and Haihe Laboratory of Sustainable Chemical TransformationsTianjin University92 Weijin RoadTianjin300072 China

The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.

关键词： Cross-coupling Diaryl ethers Chlorosilanes C—O bond cleavage Iron catalyst 3d transition metals Selectivity Regioselectivity

A new 4-Ti-added polyoxometalate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tungsten 2024年第2期6卷 465-471页

作者： Hai-Lou Li Chen Lian Guo-Yu Yang MOE Key Laboratory of Cluster Science School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 102488China

A new inorganic–organic hybrid 4-Ti-added polyoxometalate:[H_(2)N(CH_(3))_(2)]_(2)Na_(3)H_(5)[{Ti(C_(2)O_(4))(H_(2)O)}_(2){Ti(C_(2)O_(4))}_(2)(B-β-SbW_(9)O_(33))_(2)]·22H_(2)O(1)has been successfully made and further characterized by infrared spectroscopy,thermogravimetric analysis,powder X-ray diff raction and single-crystal X-ray diff raction.The polyoxoanion of 1 exhibits a Krebs-type structure that is constructed from two[B-β-SbW_(9)O_(33)]^(9)−fragments fused together by a belt of four additional Ti atoms decorated by oxalate ligands.Furthermore,1 as a heterogeneous catalyst exhibits high activity for Knoevenagel condensation under mild reaction conditions.

关键词： Polyoxometalate Ti-added POM Krebs-type structure Knoevenagel condensation

Single droplet formation by controlling the viscoelasticity of polymer solutions during inkjet printing

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第6期35卷 244-248页

作者： Dong Lv Xuelei Liu Wei Li Qiang Zhang Xinhong Yu Yanchun Han State Key Laboratory of Polymer Physics and chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied chemistry and Engineering University of Science and Technology of ChinaHefei 230026China

Inkjet printing has emerged as a potential solution processing method for large-area patterned films.During inkjet printing,a single droplet without satellite droplet is required for high-quality film.Herein,we propose a strategy for obtaining a single droplet by adjusting the reduced concentration(c/c^(*),where c^(*)is the critical overlap concentration)in the range of 1.0-1.5.Droplet formation can be categorized into three distinct regimes:(1)c/c^(*)2.0,no droplet.Furthermore,an inertial-capillary balance led to the 2/3-power scaling of the minimum radius with time for the solutions of c/c^(*)<1.0.However,for the solutions of c/c^(*)=1.0-1.5,the ligament radius decreased exponentially with time.Moreover,the Weissenberg number was higher than the critical value of 0.5,indicating that the polymer chains underwent coil-stretch transition.The viscoelastic-capillary balance dominated instead of the inertial-capillary balance.The resulting viscoelastic resistance reduced the length of the ligament and increased the velocity difference between the satellite and main droplets.Consequently,a single droplet was formed.In addition,the law can be successfully generalized to various molecular weights,molecular structures and solvents.

关键词： Inkjet printing Single droplet Satellite droplet Viscoelasticity Coil-stretch

Cascade electrolysis and thermocatalysis: a reliable system for upgrading C1 to C4 hydrocarbons

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 410-412页

作者： Chao-Yue Sun Wen Li Hai-Qing Wang institute for Advanced Interdisciplinary Research(iAIR) College of Chemistry and Chemical EngineeringUniversity of JinanJinan 250022China

The carbon cycle is important for maintaining a stable climate and carbon balance on Earth. Renewable-electricitydriven upcycling of carbon dioxide (CO_(2)) into value-added multi-carbon molecules is a potentially sus... 详细信息

关键词： cycling hydrocarbons enable

Efficient capture of difluorocarbene by pyridinium 1,4-zwitterionic thiolates:A concise synthesis of difluoromethylene-containing 1,4-thiazine derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第4期35卷 367-370页

作者： Zhiwei Chen Heyun Sheng Xue Li Menghan Chen Xin Li Qiuling Song institute of Next Generation Matter Transformation College of Materials Science&Engineering and College of Chemical Engineering at Huaqiao UniversityXiamen 361021China Fujian University Key Laboratory of Molecule Synthesis and Function Discovery College of ChemistryFuzhou UniversityFuzhou 350108China State Key Laboratory of Organometallic chemistry and Key Laboratory of Organofluorine chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

A practical method for the construction of difluoromethylene-containing 1,4-thiazine moieties using readily available diethyl bromodifluoromethanephosphonate(BrCF_(2)PO(OEt)_(2))as difluorocarbene precusor has been developed.This transformation features the efficient capture of difluorocarbene by pyridinium 1,4-zwitterionic thiolates.A series of structurally novel and functionalized difluoromethylene-containing 1,4-thiazine derivatives were thus synthesized in good yields.

关键词： Difluoromethylene Pyridinium 1 4-zwitterionic thiolates 1 4-Thiazine derivatives

Palladium(Ⅱ)-Catalyzed Markovnikov Hydroalkynylation of Unactivated Terminal Alkenes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of chemistry 2024年第1期42卷 29-34页

作者： Chuanqi Hou Pinhong Chen Guosheng Liu Sstate Key Laboratory of Organometallic chemistry and Shanghai Hongkong Joint Laboratory in Chemical SynthesisCenter for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200032China Chang-Kung Chuang institute East China Normal UniversityShanghai 200062China

Alkynes are versatile synthons in organic synthesis,as well as important structural moieties in bioactive molecules.Recently,transition metal-catalyzed hydroalkynylation of alkenes has been developed with reactive alkenes and alkenes bearing directing groups.However,the regioselective hydroalkynylation of simple alkenes is still challenging.Herein,we have developed a palladium-catalyzed Markovnikov hydroalkynylation of unactivated terminal alkenes,which provides an efficient approach for the synthesis of branched alkynyl compounds under mild conditions.This reaction features excellent functional group tolerance,good reaction yields and excellent regioselectivity.Moreover,the asymmetric hydroalkynylation reaction has also been achieved with moderate enantioselectivity by introducing a sterically bulky chiral Pyox ligand.

关键词： Palladium catalysis Alkynylpalladation Unactivated terminal alkenes Markovnikov hydroalkynylation

Heteroatom doping regulates the catalytic performance of singleatom catalyst supported on graphene for ORR

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 1086-1093页

作者： Ji-Kai Sun Yu-Wei Pan Meng-Qian Xu Lei Sun Shaolong Zhang Wei-Qiao Deng Dong Zhai institute of Molecular Sciences and Engineering Institute of Frontier and Interdisciplinary ScienceShandong UniversityQingdao 266237China College of chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental pollution.However,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the development of fuel cells.It is significant to develop catalysts with high catalytic activity of ORR.The single-atom catalysts(SACs)of Pt supported on heteroatom-doped graphene are potential candidates for ORR.Here we studied the SACs of Pt with different heteroatoms doping and screened out Pt-C_(4) and Pt-C_(3)O_(1) structures with only 0.13 V overpotential for ORR.Meanwhile,it is found that B atoms doping could weaken the adsorption capacity of Pt,while N or O atoms doping could enhance it.This regularity was verified on Fe SACs.Through the electronic interaction analysis between Pt and adsorbate,we explained the mechanism of this regularity and further proposed a new descriptor named corrected d-band center(ε_(d-corr))to describe it.This descriptor is an appropriate reflection of the number of free electrons of the SACs,which could evaluate its adsorption capacity.Our work provides a purposeful regulatory strategy for the design of ORR catalysts.

关键词： single-atom catalyst(SAC) oxygen reduction reaction(ORR) heteroatom doping corrected d-band center descriptor