检索结果-南通市图书馆

chinese Journal of chemistry 2018年第8期36卷 708-711页

作者： Youwen Sun Guozhu Zhang State Key Laboratory of Organometallic chemistry Shanghai Institute of Organic Chemistry Center for Excellence in Molecular Synthesis University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China

We report a palladium-catalyzed formal intermolecular [4＋2] cycloaddition of benzoic and acrylic acids with 1,3-dienes including the stock chemicals 1,3-butadiene and isoprene leading to synthetically useful 3,4-dihydroisocoumarins and 5,6-dihydrocoumalins. Stepwise c-h bond cleavage and annulation are likely involved in the reaction pathway. The synthetic potential of the methodology was demonstrated by two short derivatizations and total synthesis of natural product clausamine B.

关键词： palladium（ll） C-H bond activation 1,3-diene cycloaddition natural product

A density functional theory study of methane activation on MgO supported Ni_(9)M_(1) cluster:role of M on c-h activation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of chemical Science and Engineering 2022年第10期16卷 1485-1492页

作者： Juntian Niu haiyu Liu Yan Jin Baoguo Fan Wenjie Qi Jingyu Ran college of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Advanced Manufacturing Technology for Automobile Parts Ministry of EducationChongqing University of TechnologyChongqing 400050China Key Laboratory of Low-grade Energy Utilization Technologies and Systems Ministry of EducationChongqing UniversityChongqing 400044China

Methane activation is a pivotal step in the application of natural gas converting into high-value added chemicals via methane steam/dry reforming reactions.Ni element was found to be the most widely used catalyst.In present work,methane activation on MgO supported Ni–M(M=Fe,co,cu,Pd,Pt)cluster was explored through detailed density functional theory calculations,compared to pure Ni cluster.ch_(4)adsorption on cu promoted Ni cluster requires overcoming an energy of 0.07 eV,indicating that it is slightly endothermic and unfavored to occur,while the adsorption energies of other promoters M(M=Fe,co,Pd and Pt)are all higher than that of pure Ni cluster.The role of M on the first c–h bond cleavage of ch_(4)was investigated.Doping elements of the same period in Ni cluster,such as Fe,co and cu,for c–h bond activation follows the trend of the decrease of metal atom radius.As a result,Ni–Fe shows the best ability for c–h bond cleavage.In addition,doping the elements of the same family,like Pd and Pt,for ch_(4)activation is according to the increase of metal atom radius.consequently,c–h bond activation demands a lower energy barrier on Ni–Pt cluster.To illustrate the adsorptive dissociation behaviors of ch_(4)at different Ni–M clusters,the Mulliken atomic charge was analyzed.In general,the electron gain of ch_(4)binding at different Ni–M clusters follows the sequence of Ni–cu(–0.02 e)co(–0.10 e)he binding strength between catalysts and ch_(4)raises with the ch_(4)electron gain increasing.This work provides insights into understanding the role of promoter metal M on thermal-catalytic activation of ch_(4)over Ni/MgO catalysts,and is useful to interpret the reaction at an atomic scale.

关键词： ch_(4) dissociation Ni-M C-H bond activation charge transfer

Insight into the photoexcitation effect on the catalytic activation of h_(2) and c-h bonds on TiO_(2)(110)surface

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

chinese chemical Letters 2022年第10期33卷 4705-4709页

作者： Min Zhou hai-Feng Wang Key Laboratory for Advanced Materials Centre for Computational Chemistry and Research Institute of Industrial CatalysisEast China University of Science and TechnologyShanghai 200237China

Semiconductor photocatalysis holds great promise for breaking the inert chemical bonds under mild condition;however,the photoexcitation-induced modulation mechanism has not been well understood at the atomic level.herein,by performing the DFT+U calculations,we quantitatively compare h_(2) activation on rutile TiO_(2)(110)under thermo-versus photo-catalytic condition.It is found that h2 dissociation prefers to occur via the heterolytic cleavage mode in thermocatalysis,but changes to the homolytic cleavage mode and gets evidently promoted in the presence of photoexcited hole(h^(+)).The origin can be ascribed to the generation of highly oxidative lattice O-radical(O_(br)^(·−))with a localized unoccupied O-2p state.More importantly,we identify that this photo-induced promotion effect can be practicable to another kind of important chemical bond,i.e.,c-h bond in light hydrocarbons including alkane,alkene and aromatics;an exception is the c(sp^(1))-h in alkyne(hc≡ch),which encounters inhibition effect from photoexcitation.By quantitative analysis,the origins behind these results are attributed to the interplay between two factors:c-h bond energy(E_(bond))and the acidity.Owing to the relatively high E_(bond) and acidity,it favors the c(sp^(1))-h bond to proceed with the heterolytic cleavage mode in both thermo-and photo-catalysis,and the photoexcited O_(br)^(·−)is adverse to receiving the transferred proton.By contrast,for the other hydrocarbons with moderate/low E_(bond),the O_(br)^(·−)would enable to change their activation mode to a more favored homolytic one and evidently decrease the c-h activation barrier.This work may provide a general picture for understanding the photocatalytic R-h(R=h,c)bond activation over the semiconductor catalyst.

关键词： Density functional theory calculation Photocatalysis h_(2)activation C-H bond activation TiO_(2)

Theoretical Study on Pd-catalyzed Aromatic C-H bond activation

在线全文

学校读者我要写书评

暂无评论

Theoretical Study on Pd-Catalyzed Aromatic C-H Bond Activati...

Theoretical Analysis of the Mechanism of cationic Pd(Ⅱ)-catalyzed Fujiwara-Moritani Reaction

中国化学会·第十五届全国有机合成化学学术研讨会

作者： Xiao-Fei Zhang Ruo-Nan Xu Xin huang Wen-Jie chen 王彬 college of chemistry Fuzhou University college of chemical Engineering and Material Quanzhou Normal University 福州大学

Palladium catalysts can achieve cyclometallation of a molecule containing the c-h bond.The cleavage of c-h bond of the aryl bromide which would form the aromatic c-c bond with the Pd catalysts were reported by Bassoude et al.1.Our current work focuses on the reaction mechanisms of Pd-catalyzed c-h and c-h activation of aryl iodide using the density functional theory(DFT) calculation.The results show that under the weak basic condition(KcO) the c-h activation seems relatively easier, while under the strong basic condition(cscO) the c-h activation seems more favorable.The influence of different ligands in the reactions is discussed as well.The reaction undergoes oxidative addition, c-h activation(cMD process) and reductive elimination in sequence.The Pd(0)→Pd(Ⅱ)→Pd(0) catalytic cycle was established for the reaction, and the rate-determining step is c-h activation process.

关键词： Density Functional Theory Pd-catalyzed C-H bond activation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

chinese Journal of Structural chemistry 2021年第5期40卷 576-587,528页

作者：任颖王涛张婷婷贾建峰武海顺 Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityLinfen 041000China

A systematic theoretical investigation has been studied on Fujiwara-Moritani reaction between 3-methoxyacetanilide with n-butyl acrylate by means of density functional theory(DFT) calculations when two types of Pd(Ⅱ) catalysts are employed. In [Pd(MecN)_4](BF_4)_2 catalytic cycle, a 1,4-benzoquinone(BQ)-induced c-h activation of trans-(MecN)_2Pd(BQ)~(2+) with 3-methoxyacetanilide occurs as the first step to give Dc-4_(MecN), facilitating the insertion of n-butyl acrylate and β-hydride elimination, followed by recycling of catalyst through hydrogen abstraction of monocationic BQ fragment. In Pd(OAc)_(2) catalytic cycle, it is proposed that the most favored reaction pathway should proceed in dicationic mechanism involving a BQ-assisted hydrogen transfer for c-h activation by Pd active catalyst(hOAc)_(2)Pd(BQ)^(2+) to generate Dc-4_(hOAc), promoting acrylate insertion and β-hydride elimination, followed by the regeneration of catalyst to give the final product. The calculations indicate that the rate-determining step in [Pd(MecN)_(4)](BF_4)_(2) catalytic system is the acrylate insertion, while it is the regeneration of catalyst in the Pd(OAc)_(2) catalytic system. In particular, the roles of BQ and ligand effects have also been investigated.

关键词： C-H bond activation DFT studies Pd(Ⅱ)catalyst reaction mechanism

Theoretical Study of Non-heme Mn(V)-oxo complexes:Formation Mechanism,Electronic Nature,and hydroxylation Reactivity

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Structural chemistry 2021年第12期40卷 1557-1566,1551页

作者：文子豪李爽张敏熠 college of chemistry and Material Science Fujian Normal UniversityFuzhou 350007China State Key Laboratory of Structural chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

Many non-heme manganese complexes exhibit high reactivity and enantioselectivity for the activation of c-h bonds.Recently,Mn(PDP)complexes(PDP=N,N'-bis(pyridine-2-ylmethyl)-2,2,-bipyrrolidine)have been reported to activate c-h bonds selectively in the presence of carboxylic acids.In this study,we performed density functional theory calculations to investigate the formation and hydroxylation mechanisms of Mn(PDP)complexes.Our calculation results showed that Mn(Ⅲ)(PDP)complexes react with h_(2)O_(2) and carboxylic acid to form Mn(V)-oxo oxidation intermediate.The main oxidation intermediate,[(PDP)Mn(IV)(O…Oc(O)ch_(3))^(2-)·]^(2+),was found to have the characteristics of S(Mn)=3/2 manganese(IV)center antiferromagnetically coupled to a σ^(*)_(O-O) radical,where the O-O bond is not completely broken.Furthermore,[(PDP)Mn(IV)(O…Oc(O)ch_(3)^(2-)·]^(2+) was shown to have two single electron-accepting orbitals(α Mn-d_(xy) and βσ^(*)_(O-O))that can simultaneously interact with a doubly occupied electron-donating orbital(σ_(c-h))of substrate.Therefore,[(PDP)Mn(IV)(O…Oc(O)ch_(3)^(2-)·]^(2+) species can act as a two-electron oxidant for the c-h bond flinctionalization.As a result,the c-h bond hydroxylation by [(PDP)Mn(IV)(O…Oc(O)ch_(3)^(2-)·]^(2+) species was a single step.Following the h-abstraction with a low barrier of 4.5 kcal/mol,hydroxyl group would immediately rebound to the radical carbon without barrier.These results provide new insights toward the further development of non-heme manganese catalysts.

关键词： C-H bond activation non-heme manganese complex homogeneous catalysis density functional theory calculations

Theoretical Study of Iron Porphyrin Imine Specie of P411 Enzyme:Electronic Structure and Regioselectivity of c(sp^(3))-h Primary Amination

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Structural chemistry 2021年第11期40卷 1411-1422,1405页

作者：李爽文子豪张敏熠 college of chemistry Fuzhou UniversityFuzhou 350108China Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002China

The cytochrome P411 enzyme is a variant of cytochrome P450_(BM3) from Bacillus megaterium whose active site is an iron porphyrin imine([Fe(Por)(Nh)]^(-))specie.This specie has been reported to successfully promote the primary amination of benzylic and allylic c(sp^(3))-h bonds.We employed density functional theory to study the electronic structure of the active site of P411 enzyme and the primary amination of c-h bond reaction that it catalyzes.The calculated spin densities and orbital values indicate the existence of resonance in this specie;namely,[(por)(–Oh)Fe^(Ⅳ)–N^(2-)–h]^(-)↔[(por)(–Oh)Fe^(Ⅲ)–N^(·-)–h]^(-).The amination of c(sp^(3))-h bonds consists of two main reaction steps:hydrogen-atom abstraction and radical recombination,and the former is demonstrated to be the rate-determining step.Furthermore,we studied the regioselectivity of the amination of primary and secondary c(sp^(3))-h bonds.Our calculations indicated that the secondary c(sp^(3))-h bonds of the substrate would be more favored for the activation by P411 enzyme.These results provide valuable information for understanding the properties and selectivity of c-h/c-N bond-activation reactions catalyzed by the P411 enzyme or other similar enzymes.

关键词： DFT cytochrome P411 enzyme C-H bond activation enzyme catalysis

Synthesizing active and durable cubic ceria catalysts(<6 nm)for fast dehydrogenation of bio-polyols to carboxylic acids coproducing green h_(2)

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第3期9卷 529-543页

作者： Mengyuan Liu Puhua Sun Guangyu Zhang Xin Jin chaohe Yang honghong Shan State Key Laboratory of heavy Oil Processing College of Chemical EngineeringChina University of PetroleumNo.66 Changjiang West RoadQingdaoShandong266580China SINOPEc Research Institute of Safety Engineering co. Ltd.No.339 Songling RoadQingdaoShandong266000China

Dehydrogenation is considered as one of the most important industrial applications for renewable energy.cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area.Large particle size(>20 nm)and less surface defects,however,hinder further application of ceria materials.herein,an alternative strategy involving lactic acid(LA)assisted hydrothermal method was developed to synthesize active,selective and durable cubic ceria ofhydrogenation reactions.Detailed studies of growth mechanism revealed that,the carboxyl and hydroxyl groups in LA molecule synergistically manipulate the morphological evolution of ceria precursors.carboxyl groups determine the cubic shape and particle size,while hydroxyl groups promote compositional transformation of ceria precursors into ceO_(2) phases.Moreover,enhanced oxygen vacancies(Vo)on the surface of ceO_(2) were obtained owing to continuous removal of O species under reductive atmosphere.cubic ceO_(2) catalysts synthesized by the LA-assisted method,immobilized with bimetallic Ptco clusters,exhibit a record high activity(TOF:29,241 h^(-1))and Vo-dependent synergism for dehydrogenation of bio-derived polyols at 200℃.We also found that quenching Vo defects at air atmosphere causes activity loss of Ptco/ceO_(2) catalysts.To regenerate Vo defects,a simple strategy was developed by irradiating deactivated catalysts using hernia lamp.The outcome of this work will provide new insights into manufacturing durable catalyst materials for aqueous phase dehydrogenation applications.

关键词： cubic ceria Oxygen vacancy Dehydrogenation C-H bond activation

The mechanism of hydrogen abstraction by high valence transition metal oxo compounds

在线全文

学校读者我要写书评

暂无评论

Journal of Energy chemistry 2016年第6期25卷 1045-1050页

作者： Gang Fu Ruming Yuan huilin Wan Xin Xu Department of chemistry State Key Laboratory for Physical Chemistry of Solid Surfaces College of Chemistry & Chemical Engineering Xiamen University Department of chemistry MOE Laboratory for Computational Physical Science Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsFudan University

We present here a systematic theoretical study to explore the underlying mechanisms of the h abstraction reaction from methane. Various abstracting agents have been modeled, using oxygen radicals and a set of high valence metal oxo compounds. Our calculations demonstrate that although h abstraction from ch3-h by metal oxoes can be satisfactorily fitted into the Polanyi correlation on the basis of oxygen radicals, the mechanisms behind are significantly different. The frontier orbital analyses show that there are three electrons and three active orbitals (3e, 3o) involved in h abstraction by oxygen radicals; whereas an additional orbital of pi(M-O)* is involved in h abstraction by M = O, resulting in a (4e, 4o) interaction. In terms of valence bond state correlation diagram, we find that h abstraction by a metal oxo may benefit from the contribution of ionic resonance structures, which could compensate the penalty of opening the M-O pbond. We believe that these findings can help to design more effective catalysts for the activation of light alkanes. (c) 2016 Science Press and Dalian Institute of chemical Physics, chinese Academy of Sciences. Published by Elsevier B. V. and Science Press. All rights reserved.

关键词： C-H bond activation Polanyi relationship Oxygen radical Valence bond state correlation diagram DFT calculation

Transition Metal catalyzed Direct c-2 Alkynylation of Indole

在线全文

学校读者我要写书评

暂无评论

Transition Metal Catalyzed Direct C-2 Alkynylation of Indole

作者： Yasir Mumtaz 南京理工大学

学位级别：硕士

This thesis investigated,palladium-catalyzed direct c2 alkynylation of N-2-pyrimidyl indoles,affording a series of c2 alkynylated indole derivatives in good yields.In addition we developed the direct alkynylation of 3-methyl-2-phenylpyridine.The main contents are outlined as follows:Indole derivatives are a kind of organic heterocyclic compounds with physiological activity and important drug intermediates.As a parent,nuclear structure is commonly used in anticancer drugs with high activity,and N-pyrimidine indole is used as substrate.herein,a palladium-catalyzed direct c2 alkynylation of N-2-pyrimidyl indoles was described by using 2-Bromo-l-triisopropylsilyl acetylene as an alkyne reagents.This reaction exhibited excellent regioselectivity of indoles by using the pyrimidine moiety as the directing group,and the desired mono-substituted alkynylated products were obtained in high yields.This reaction proceeded smoothly under the following given conditions and showed good functional group compatibility as shown in Figure 0.1.Figure 0.1 Direct c2 alkynylation of N-2-pyrimidyl indole

关键词： Alkynylation Palladium-catalyzed N-2-pryimidyl indole C-H bond activation