铜、镍、钯催化C-C偶合反应的研究进展

偶合反应是有机合成中的一种重要反应,本文综述了Cu、Ni、Pd等不同形式催化剂催化C-C偶合反应的研究进展,并展望优化该类反应的条件．     

Fe和Co催化的碳-碳偶联反应的最新进展

作为廉价而且低毒的金属, Fe和Co是发展催化剂的理想元素. 同时由于Fe和Co有着多种氧化还原价态, 它们的催化化学应该具有极其丰富的内容. 然而由于种种原因, Fe和Co的催化剂很少得到有机化学家的关注. 直到最近几年, 人们才发现Fe和Co的催化剂可以很好地催化碳-碳偶联反应. 综述了Fe和Co催化碳-碳偶联反应的条件、产率和选择性; 探讨了这些新奇反应的可能机理; 并介绍了这些反应在复杂化合物合成中的应用.     

Theoretical Study on the Mechanism of Sonogashira Coupling Reaction

The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT （density functional theory） calculations. The model system studied consists of Pd（PH3）2 as the starting catalyst complex, phenyl bromide as the substrate and acetylene as the terminal alkyne, without regarding to the co-catalyst and base. Mechanistically and energetically plausible catalytic cycles for the cross-coupling have been identified. The DFT analysis shows that the catalytic cycle occurs in three stages： oxidative addition of phenyl bromide to the palladium center, alkynylation of palladium（Ⅱ） intermediate, and reductive elimination to phenylacetylene. In the oxidative addition, the neutral and anionic pathways have been investigated, which could both give rise to cis-configured palladium（Ⅱ） diphosphine intermediate. Starting from the palladium（Ⅱ） diphosphine intermediate, the only identifiable pathway in alkynylation involves the dissociation of Br group and the formation of square-planar palladium（Ⅱ） intermediate, in which the phenyl and alkynyl groups are oriented cis to each other. Due to the close proximity of phenyl and alkynyl groups, the reductive elimination of phenylacetylene proceeds smoothly.     

Fe(100)表面Cu单层膜上CO的吸附,解离以及C-C偶合反应

采用密度泛函方法研究了Fe(100)表面Cu单层膜上CO的吸附,直接解离,氢助解离以及C-C偶合反应.相比洁净的Fe(100)表面,在Fe(100)的单层Cu膜上,CO的吸附和活化都减弱了.特别是,相比Fe(100)上CO的解离能垒1.08 eV,铜单层膜上CO解离能垒高达2.4 eV.在H原子共吸附的情况下,Fe(1...     

原位生成的水溶性Salen-Pd配合物催化微波促进水中的C-C偶联反应

将一种水溶性Salen,N,N’-双[（5-磺酸基-2-羟基）苄基]缩N,N’-二甲基-1,2-乙二胺（L）与醋酸钯原位生成水溶性Salen-Pd配合物,该水溶性钯配合物应用于催化微波加热的水中的Heck和Sonogashira碳-碳偶联反应.在优化反应条件之后,对溴苯衍生物与乙烯衍生物的Heck偶联反应以及溴苯衍生物与苯乙炔及其衍生物之间的Sonogashira偶联反应进行了考察.发现,在优化的反应条件下,无论是Heck反应,还是Sonogashira偶联反应,都能得到很好的收率.在有机物分离之后,水相继续循环使用4次,在水相的前3次循环使用时,都获得了不错的收率.     

介孔SBA-15棒负载的Pd3Cl催化剂催化Sonogashira偶联反应（英文）

通过静电吸引策略将具有高度分散性的原子精确纳米团簇[Pd3Cl(PPh2)2(PPh3)3]+(Pd3Cl)负载在介孔SBA-15棒上。结构明确的Pd3Cl/SBA-15催化剂在以水作为溶剂以及温和的反应条件下对催化Sonogashira碳-碳偶联反应展现了较好的催化性能以及循环性。在此基础上,我们研究了Pd3Cl团簇结构与性能之间的关系,并证实内核的Pdδ+(0<δ<2)与配体之间的协同效应是催化反应的关键。     

CO偶联临氢反应Pd-Fe/Al2O3催化剂的XPS研究

 利用XPS及氩离子溅射等技术对CO偶联和临氢反应中所用催化剂\r\n表面活性组分和助剂的含量及其化学状态进行了分析，并通过测定氢在\r\n催化剂表面的化学吸附，以及氢浓度对催化剂活性的影响，探讨了CO偶\r\n联反应中催化剂临氢失活的主要原因．XPS表征结果表明，CO偶联反应\r\n中催化剂活性组分以Pd0和Pd2＋形式共存；而临氢反应后仅以Pd0形式\r\n存在，助剂FeO从催化剂的内部向表面迁移且有少量Fe2＋转变为Fe3＋\r\n．催化剂临氢失活的主要原因是H2在活性组分Pd及助剂Fe（主要是FeO\r\n）表面均可形成解离吸附，形成的金属氢化物可在低活化能条件下发生\r\n迁移．这种迁移有利于副产物乙醇的生成，从而削弱了CO偶联主反应，\r\n催化剂表面活性组分Pd的相对含量减少，并几乎处于钝化状态，导致临\r\n氢反应中CO转化率、草酸二乙酯选择性及空时收率均下降．停止通入H\r\n2后，催化剂的活性可恢复至正常状态．     

L-lysine-Pd Complex Supported on Fe3O4 MNPs: a novel recoverable magnetic nanocatalyst for Suzuki C-C Cross-Coupling reaction

In this work, L-lysine-Pd Complex, immobilized onto the surface of Fe₃O₄ MNPs, was successfully prepared via simple and inexpensive procedure. The prepared nanocatalyst was considered as a robust and clean nano-reactor catalyst for the Suzuki and Heck C-C Cross-Coupling reactions in water as the green condition. This eco-friendly heterogeneous catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP), X-ray mapping, BET, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. The use of a green medium, easy separation and workup, excellent reusability of the nanocatalyst and short reaction time are some outstanding advantages of this method.     

草酰氯一价正离子构象及其碳—碳键反应活性的理论研究

用密度泛函方法BHandHLYP在6-311+G（d）和6-311+G（2df）水平上对草酰氯 的一价正离子［（ClCo）_2~+］作了构象分析，结果表明，（ClCo）_2~+具有平面 反式和交叉式两种稳定构象，交叉构象存在超共轭现象，此外，对草酰氯离子、中 性分子各解离通道初级反应的Gibbs自由能的计算，发现草酰氯离子C—C键解离通 道的反应活性大于中性分子，对该通道进一步做了反应机理研究，证实了热力学结 论，并且与实验相一致，对草酰氯离子的振动频率和键耦合常数的研究表明其碳— 碳键解离具有选键性。     

Glaser偶联反应研究进展

回顾了近年来Glaser偶联反应的研究进展, 讨论了这一反应在共轭聚合物合成中的应用, 并对其反应机理进行了探讨.     

双功能金属卟啉催化环氧化合物与 CO2 偶联反应合成环碳酸酯

 合成了新颖的双功能水溶性金属卟啉 催化剂 M(TTMAPP)I4(X) (M = Co, Fe, Mn 和 Cr; X = OAc, CF3COO, CCl3COO, OTs, Cl, Br 和 I), 研究了它们催化 CO2 与末端环氧化合物合成环碳酸酯的偶联反应. 分别考察了反应温度、不同金属的 Lewis 酸中心、抗衡离子和催化剂重复使用次数对反应性能的影响. 当以 Co(III)(TTMAPP)I4(OAc) 为催化剂, 底物与催化剂摩尔比为 1 000, 温度为 353 K, CO2 压力为 667 kPa 和无溶剂条件下, 反应 5 h 时丙烯环碳酸酯收率为 95.4%. 在 298 K, 底物与催化剂之比为 2 000 时, 加入 1 ml 甲醇, 反应 24 h 丙烯环碳酸酯收率为 19.4%. 催化剂可以用乙醚回收, 循环使用 5 次后催化剂活性没有明显降低.     

CO偶联反应中氧对Pd－Fe／α－Al2O3催化剂活性的影响

 在CO常压气相催化偶联合成草酸酯反应体系中，考察了原料气CO中不同氧杂质含量和不同反应温度对钯系催化剂活性的影响．结果表明，随着氧含量的增加和反应温度的升高，CO的转化率和草酸二乙酯（DEO）的空时收率升高，但DEO的选择性下降，且有副产物乙酸乙酯生成 ；氧杂质的存在同时加快了CO偶联主副反应速率．根据实验现象及XPS表征结果探讨了催化剂活性变化规律的机理，并考察了在反应温度下无CO偶联反应时氧对钯系催化剂中活性组分钯及助剂铁的氧化作用．实验结果表明，氧引起的钯系催化剂活性的改变具有可逆性．     

光催化有机物偶联/芳构化放氢反应研究进展

光催化氧化还原反应具有绿色、高效、安全等优势,已经在有机化学中得到广泛关注.介绍了基于光催化的偶联/芳构化放氢反应,通过使用光催化剂/催化剂的双催化体系,可用于光催化有机碳-碳和碳-杂原子成键反应,且反应中氢气是唯一的副产物.强调了有机光氧化还原体系的构建与催化机理.     

Density Functional Study on the Mechanism of Amadori Rearrangement Reaction

The reaction mechanism of amadori rearrangement in the initial stage of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution.Cyclic ribose and glycine were taken as the model in the amadori rearrangement.Reaction mechanisms have been proposed,and possibility for the formation of different compounds has been evaluated through calculating the relative energy changes for different steps of the reaction by following the total mass balance.The calculations reveal that the amadori rearrangement initialized via the intramolecular rearrangement,transferring one proton from N(3) to O(4) atom.In the next step,the second proton is also transferred from N(3) to O(4) atom,corresponding to the cleavage of C(4)-O(4) bond and the release of one water molecule.Then another proton is transferred from N(3) to C(5) atom via TS3 with the reaction barrier of 58.3 kcal·mol-1 after tunneling the effect correction calculated at the B3LYP/6-31+G(d) level of theory,and this step is rate limiting for the whole catalytic cycle.Ultimately,the product is generated via keto-enolic tautomerization.Present calculation could provide insights into the reaction mechanism of Maillard reaction since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.     

钯系催化剂的氨中毒研究

 考察了CO常压气相偶联合成草酸酯反应体系中在不同氨含量下P\r\nd系催化剂活性随反应时间的变化．结果表明，随着氨含量的增加，催\r\n化剂活性降低的速率加快，氨含量不超过0．54％时，仅引起催化剂活\r\n性下降，但不会造成催化剂完全失活；当氨含量达1．16％时，催化剂\r\n活性随反应时间迅速下降，直至完全失活．同时，观测了催化剂氨中毒\r\n的不可逆性．利用XPS和TEM表征手段探讨了Pd系催化剂氨中毒机理，并\r\n分析了在工业生产条件下催化剂氨中毒不可逆性的原因．     

Glaser反应研究新进展

Glaser偶联反应是合成二炔化合物的重要反应,广泛应用于有机合成、材料化学等领域.介绍了近年来Glaser偶联反应中溶剂、氧化剂、底物等领域的研究新进展,指出Glaser偶联反应在不断加深其各方面绿色化研究的同时,多功能团底物的Glaser偶联反应与不对称的Glaser偶联反应也值得关注.     

Direct Coupling Reaction of Diaryl Methanol with Ketones or Aldehydes Catalyzed by AlCl3

A novel coupling reaction of diaryl methanols with ketones or aldehydes has been developed under the catalysis of AlCl₃. Various ketones and aldehydes could couple with 9H-xanthen-9-ol smoothly, affording coupling products in 48% –88% yields. A plausible mechanism using AlCl₃ to activate both diaryl methanol and ketone or aldehyde is proposed.     

通用聚丙烯的偶联反应

通过熔融接枝的方法在聚丙烯(PP)分子链上接枝甲基丙烯酸缩水甘油酯(GMA),制得PP接枝物PP-g-GMA,然后采用多个胺基的偶联剂聚六亚甲基胍(PHMG)对其进行偶联反应,制备偶联的聚丙烯(MPP)。通过与通用聚丙烯(EPS)以及进口专用料(PF-814)的对比,考察了经过偶联改性的MPP熔体的流变特性。结果表明:与原料EPS和PF-814相比,改性后MPP熔体的低频剪切区储能模量、挤出胀大、稳态柔量、零剪切黏度及熔体强度等都有明显增大。     

Comparison of Oxidative Aromatic Coupling and the Scholl Reaction

Does the dehydrogenative coupling of aromatic compounds mediated by AlCl₃ at high temperatures and also by FeCl₃, MoCl₅, PIFA, or K₃[Fe(CN)₆] at room temperature proceed by the same mechanism in all cases? With the growing importance of the synthesis of aromatic compounds by double C? H activation to give various biaryl structures, this question becomes pressing. Since some of these reactions proceed only in the presence of non‐oxidizing Lewis acids and some only in the presence of certain oxidants, the authors venture the hypothesis that, depending on the electronic structure of the substrates and the nature of the “catalyst”, two different mechanisms can operate. One involves the intermediacy of a radical cation and the other the formation of a sigma complex between the acid and the substrate. The goal of this Review is to encourage further mechanistic studies hopefully leading to an in‐depth understanding of this phenomenon.     

Reactions of the dications C7H6, C7H7, and C7H8 with methane: Predominance of doubly charged intermediates

The reactions of methane with the dications C₇H₆²⁺, C₇H₇²⁺, and C₇H₈²⁺ generated by electron ionization of toluene are studied using mass-spectrometry tools. It is shown that the reactivity is dominated by the formation of doubly charged intermediates, which can either eliminate molecular hydrogen to yield doubly charged products or undergo charge-separation reactions leading to the formation of a methyl cation and the corresponding C₇H_n+1⁺ monocation. Typical processes observed for dications, like electron transfer or proton transfer, are largely suppressed. The theoretically derived mechanism of the reaction between C₇H₆²⁺ and CH₄ indicates that the formation of the doubly charged intermediate is kinetically preferred at low internal energies of the reactants. In agreement, the experimental results show a pronounced hydrogen scrambling and dominant formation of the doubly charged products at low collision energies, whereas direct hydride transfer prevails at larger collision energies.