铜络合物催化剂用于甲醇氧化羰化合成碳酸二甲酯(英文)

报道了一系列铜与含氮、氧、磷配体形成的配位催化剂用于甲醇氧化羰化合成碳酸二甲酯的研究结果。在１２０℃～１３０℃、３．０ ＭＰａ的反应条件下,氯化亚铜／联吡啶配位催化剂具有最好的活性、选择性和稳定性。在实际反应条件下的挂片试验结果表明,氯化亚铜／联吡啶催化剂对一种特种不锈钢材料的腐蚀速率为０．０２４毫米／年。     

CuCl/菲咯啉/甲基咪唑催化甲醇/乙醇氧化羰化一步合成碳酸甲乙酯

 研究了CuCl与含氮杂环化合物配体1, 10-菲咯啉(phen)和N-甲基咪唑(NMI)形成的配合物催化剂对甲醇/乙醇氧化羰化一步合成碳酸甲乙酯(MEC)反应的催化活性. 讨论了配体的配比、甲醇和乙醇的相对用量、温度及压力等因素对甲醇和乙醇的转化率及MEC产率的影响. 结果表明,CuCl/phen/NMI原位配合物催化剂对氧化羰化一步合成MEC反应具有较高的催化活性. 配体phen及NMI对反应产物的选择性有明显的调变作用,甲醇和乙醇的配比对产物分布有很大的影响. 在V(MeOH)/V(EtOH)=0.25,c(CuCl)=0.20 mol/L,n(CuCl)∶n(NMI)∶n(phen)=1∶1.25∶1.25,p=2.40 MPa,θ=120 ℃的条件下反应2 h,甲醇的转化率为44.3%,乙醇的转化率为22.3%,MEC的产率为10.4%.     

氧化羰化法合成碳酸甲乙酯热力学及催化性能的研究

研究了在甲醇、乙醇温和溶液中,氧化羰化一步合成不对称碳酸甲乙酯(MEC)反应。通过热力学计算考察了反应的可行性及程度。计算结果表明,在298.2K下主反应平衡常数为2.39×1080,说明此反应的可行性和程度均很大。实验发现在氧化羰化合成碳酸甲乙酯的过程中,不仅存在氧化羰化过程,同时也存在酯交换过程;含氮席夫碱(Schiff)的种类,甲醇和乙醇相对用量,反应温度和压力对碳酸甲乙酯(MEC)的合成均有影响。当以氯化亚铜(CuCl) 1,10 菲罗啉(phen) N 甲基咪唑(NMI)为催化剂时,摩尔比n(CuCl)∶n(NMI)∶n(phen)=1∶1.25∶1.25,在393K,2.4MPa,VMeOH∶VEtOH=2∶8,CuCl浓度为0.20mol L的条件下,反应2h,甲醇的转化率为44.3%,乙醇的转化率为22.3%,MEC产率为10.4%。与单纯CuCl催化剂相比,甲醇和乙醇的转化率分别提高17倍和9倍,MEC产率提高74倍。对氧化羰化反应机理也进行了探讨。     

非光气含氮化合物催化羰化研究进展

本文对近几年来非光气含氮化合物羰化合成氨基甲酸酯及二取代脲的方法进行了概述,主要包括使用钯、钌、铑、硒、金等催化体系以一氧化碳为羰化剂进行的催化氧化羰化和催化还原羰化反应过程,以及使用碱催化体系以二氧化碳和碳酸二甲酯等为羰化剂的反应过程和机理.     

有机金催化胺氧化羰化制氨基甲酸酯

自Haruta等报道高分散担载金催化剂对CO有良好的低温水除活性以来,金催化剂的研究开发开始受到关注,各种提载型金催化剂在选择氧化、氮氧化物消除、选择加氢、甲烷完全氧化以及均相有机金配合物催化剂在醇醛缩合、烯烃羰化、锡烷的偶联等反应中均取得了相当好的效果,但与Pt和Pd等贵金属相比,金作为具有潜在多种催化能力的催化材料了解尚少。现在工业上主要使用胺类化合物与剧毒的光气反应制取异氰酸酯,该反应造成设备腐蚀和环境污染,因此用胺类化合物氧化羰化或硝基化合物的还原羰化合成氨基甲酸酯,然后热裂解制取相应的异氰酸酯得到广泛研究,过去主要以含氮配体配位的钯催化剂为代表的贵金属为催化剂催化羰化合成氨基甲酸酯,以有机金配合物作为含氮化合物羰化催化剂的研究则未见报道,本文首次将有机金配合物作为胺类化合物氧化羰化制取氨基甲酸酯的催化剂,取得了与钯催化剂相当的催化效果,反应如下：R（NH2）n CO O2 R^1OH[Au(PPh3)x]yZ／→／PPh3R(NHCO2R^1)n H2O R=Ar-,RCH2-;R^1=CH3-,CH3CH2-;n=1 or 2,x=1 or 2,y=1 or 2;Z=cl,NO3,S。     

膦配体电子和空间效应对钯催化羰化酯化反应的影响

膦配体修饰的钯催化剂在不饱和化合物羰化酯化反应中使用广泛,其催化活性在很大程度上取决于金属周围的配体环境。膦配体电子和空间效应的调变,可以实现定向催化,甚至可以预测催化行为。新催化反应的开发和现有催化反应的优化都可以通过膦配体的合理设计来实现。配体已经是成为公认的最重要的需要详细研究的变量之一。本文综述了钯催化烯烃羰化酯化反应中,单齿膦配体、双齿膦配体、半稳定膦配体电子和空间效应对活性和选择性的调控作用,并对面临的问题和未来的发展方向进行了探讨,以期对未来设计高效高选择性羰化酯化反应催化体系提供指导。     

高效可循环离子型钯配合物催化羰化Sonogashira反应

炔酮类化合物作为一类具有生物活性的分子,是天然产物全合成中构建杂环类化合物的重要中间体.炔酮类化合物的传统合成方法是通过过渡金属催化金属有机炔烃和酰氯的交叉偶联,但存在酰氯本身稳定性和底物官能团耐受力较差的缺点.近年来,钯催化的羰化Sonogashira反应(末端炔烃和芳基卤化物与CO的偶联反应)成为合成炔酮类化合物更为直接和有效的方法,其中与钯中心原子配位的配体的电子效应和空间效应可显著调控钯配合物的催化性能.但均相钯催化的羰化Sonogashira反应体系存在催化剂流失、分离困难和难以循环使用的问题.我们以2-(1-咪唑基)噻唑为母体分子,合成了具有P,S,N杂合配体特征的配体L1,同时将配体L1通过与MeOTf的季铵化反应得到相应的离子型膦配体L2.在此基础上,利用L1和L2与过渡金属中心的配位作用合成相应的钯配合物1A和2A.由于L1和L2中含有多种不同配位能力的配体(P-配体,S-配体和/或N-配体),故通过N/S杂原子对Pd-中心原子的协同弱配位作用,可以调变相应钯配合物对羰化Sonogashira反应的催化性能.另外,2A中具有强吸电子效应的正电荷的存在,使其结构和催化性能也必然不同于中性配合物1A.实验结果表明,在温和的反应条件(90℃,lh,CO压强1.0 MPa)下,对于碘苯和苯乙炔的羰化Sonogashira偶联反应,1A体现出优于2A的催化性能,TOF值达到840 h-1;但反应温度提高到120℃时,1A的TOF高达3560 h-1,2A的TOF为2960 h-1.与L1的2JP-Se=744 Hz相比,L2的2JP-Se=768 Hz,说明L2中具有吸电子效应的正电荷的存在降低了相应P原子的σ给电子能力(2JP-Se数值越大,相应膦配体的6给电子能力越弱);同时,1A中具有弱配位能力的N配体的缺失削弱了配体对Pd活性中心的稳定作用.在底物普适性研究中发现,4-硝基溴苯在相同反应条件下几乎得不到羰化Sonogashira偶联产物.而将反应体系中的CO换为同样压强下的N2,却可以顺利实现Sonogashira偶联反应.我们推测,在CO氛围下形成的pd0-CO活性物种(与N2氛围下形成的Pd0活性物种相比)具有相对较低的对底物的氧化加成能力.离子型钯配合物2A的优势在于,当将其与室温离子液体[Bmim]PF6(溶剂)结合使用,在2A催化碘苯与苯乙炔的羰化Sonogashira偶联反应过程中,循环使用8次催化性能没有明显下降.     

DBN催化剂的制备及其在甲醇羰化反应中的应用

考察了运用自制的1,5-二氮杂双环[4.3.0]壬烯-5(DBN)催化剂在甲醇羰化合成甲酸甲酯(MF)反应中的活性实验结果表明,DBN催化剂在环氧丙烷(PO)存在下对甲醇羰化合成甲酸甲酯反应有良好的催化作用。94℃反应30min,产物甲酸甲酯的摩尔收率达40.4×10~(-2)、空时收率高达904g·L~(-1)·h~(-1)。DBN的活性比同温同压下甲醇钠催化剂的高2.5倍。     

PROMOTERS IN THE CATALYST SYSTEM FOR METHANOL CARBONYLATION TO METHYL FORMATE

在一个机械搅拌式反应器中，在反应温度为６０～９０℃，压力为３～６ＭＰａ条件下试验了几种不同类型的化合物作为甲醇催化羰化合成甲酸甲酯碱金属醇碱催化剂的助催化剂。结果发现，在甲醇羰化制甲酸甲酯反应中，是助催化剂的极性而不是碱性起着重要的作用。同时证明，强极性非质子型化合物对该羰化反应具有良好的助催效果，乙腈则是一个例外。     

非光气法合成碳酸二甲酯

ＣｕＣｌ２，ＣｕＣｌ和ＣｕＣｌ配位催化剂用于甲醇液相氧化羰化合成碳酸二甲酯，发现ＣｕＣｌ－α－ＤＰＹ配合物催化剂具有较好的活性和选择性。     

Intermolecular hydrogen bonds in hetero-complexes of biologically active aromatic ligands: Monte Carlo simulations results

We report results of the Monte Carlo simulations of systems containing heterodimers of biological active ligands and water molecules. The study was designed to identify the possible formation of intermolecular hydrogen bonds in such systems in order to investigate the molecular mechanisms of hetero-association of aromatic ligands in aqueous solution. The geometry optimization and the calculation of the atomic charges of free ligands were carried out at DFT/B3LYP level of theory. Monte Carlo simulations with Metropolis algorithm were used to determine the low energy conformations of heterodimers in water clusters. The analysis of the Monte Carlo simulation results allows us to describe in detail the hydration properties of all investigated heterodimers and to determine the intermolecular hydrogen bonds between the functional donor–acceptor groups for some of hetero-associates under investigation. In the case of heterodimers without intermolecular hydrogen bonds, the additional stabilization of these hetero-complexes can be explained by the formation the water bridges between donor and acceptor groups of the ligands.     

咪唑类化合物-CuCl络合催化剂在甲醇氧化羰基化反应中的催化性能

研究了咪唑及其衍生物配合CuCl对甲醇液相氧化羰化合成碳酸二甲酯的催化性能。筛选出溶解性好、腐蚀性小且催化活性高的多功能助催剂。实验结果表明，反应体系中加入N-甲基咪唑后，CuCl可以完全溶解。当催化剂的浓度为0.2 mol/L, N-甲基咪唑与CuCl的量为4∶1，反应温度为120 ℃，反应压力为2.40 MPa，CO与O2的进气比2∶1，反应3 h的条件下甲醇的摩尔转化率为15.4%，选择性为98%以上。从腐蚀性试验结果看，50 ℃时，加入N-甲基咪唑化合物后，Q235钢在CuCl/CH3OH/H2O/CO/O2体系中的腐蚀速率为0.22mm/a，缓蚀效率为94.5%。动力学研究表明，反应近似为一级，加入N-甲基咪唑后，反应速率常数为0.15 min－1。     

Evaluation of C4 diphosphine ligands in rhodium catalysed methanol carbonylation under a syngas atmosphere: synthesis, structure, stability and reactivity of rhodium(I) carbonyl and rhodium(III) acetyl intermediates

The carbonylation of methanol to acetic acid is a hugely important catalytic process, and there are considerable cost and environmental advantages if a process could be designed that was tolerant of hydrogen impurities in the CO feed gas, while eliminating by-products such as propionic acid and acetaldehyde altogether. This paper reports on an investigation into the application of rhodium complexes of several C(4) bridged diphosphines, namely BINAP, 1,4-bis(diphenylphosphino)butane (dppb), bis(diphenylphosphino)xylene (dppx) and 1,4-bis(dicyclohexylphosphino)butane (dcpb) as catalysts for hydrogen tolerant methanol carbonylation. An investigation into the structure, reactivity and stability of pre-catalysts and catalyst resting states of these complexes has also been carried out in order to understand the observations in catalysis. Rh(I) carbonyl halide complexes of each of the ligands have been prepared from both [Rh(2)(CO)(4)Cl(2)] and dimeric mu-Cl-[Rh(L)Cl](2) complexes. These Rh(I) carbonyl complexes are either dimeric with bridging phosphine ligands (dppb, dcpb, dppx) or monomeric chelate complexes. The reaction of the complexes with methyl iodide at 140 degrees C has been studied, which has revealed clear differences in the stability of the corresponding Rh(III) complexes. Surprisingly, the dimeric Rh(I) carbonyls react cleanly with MeI with rearrangement of the diphosphine to a chelate co-ordination mode to give stable Rh(III) acetyl complexes. The Rh acetyls for L=dppb and dppx have been fully characterised by X-ray crystallography. During the catalytic studies, the more rigid dppx and BINAP ligands were found to be nearly 5 times more hydrogen tolerant than [Rh(CO)(2)I(2)](-), as revealed by by-product analysis. The origin of this hydrogen tolerance is explained based on the differing reactivities of the Rh acetyls with hydrogen gas, and by considering the structure of the complexes.     

Revisiting the electronic excited-state hydrogen bonding dynamics of coumarin chromophore in alcohols: Undoubtedly strengthened not cleaved

In the present work, the electronic excited-state hydrogen bonding dynamics of coumarin chromophore in alcohols is revisited. The time-dependent density functional theory (TDDFT) method has been performed to investigate the intermolecular hydrogen bonding between Coumarin 151 (C151) and methanol (MeOH) solvent in the electronic excited state. Three types of intermolecular hydrogen bonds can be formed in the hydrogen-bonded C151–(MeOH)₃ complex. We have demonstrated again that intermolecular hydrogen bonds between C151 and methanol molecules can be significantly strengthened upon photoexcitation to the electronically excited state of C151 chromophore. Our results are consistent with the intermolecular hydrogen bond strengthening in the electronically excited state of Coumarin 102 in alcoholic solvents, which has been demonstrated for the first time by Zhao et al. At the same time, the electronic excited-state hydrogen bond cleavage mechanism of photoexcited coumarin chromophores in alcohols proposed in some other studies about the hydrogen bonding dynamics is undoubtedly excluded. Hence, we believe that the two contrary dynamic mechanisms for intermolecular hydrogen bonding in electronically excited states of coumarin chromophores in alcohols are clarified here.     

氢对气相甲醇羰基化催化体系的影响

 主要讨论了氢对甲醇气相羰基化催化体系的影响．采用多孔碳化聚偏二氯乙烯小球负载金属镍催化体系，在不同进气条件下进行甲醇羰基化反应，得到不同氢含量时催化剂的活性和稳定性数据，以及氢对催化体系的微扰数据，并对催化剂的表面形态用SEM进行了表征，以评价氢的影响．从三个方面分析了氢对气相甲醇羰基化催化体系的影响，认为适量存在的氢对长时间保持催化剂活性是有利的．     

The Effects of Various Alcohols on the Stability of Melittin: A Molecular Dynamics Study

In this study, 200 ps molecular dynamics simulations were conducted to investigate the effects of various alcohols on the structural stability of melittin. The averaged helicity of melittin remained 80% in pure butanol, whereas it was below 60% both in pure water and in pure methanol. The α‐helix propensity of melittin increased with the aliphatic chain length of the alcohol. Charge‐charge interaction between Lys21 and Arg24 and polar‐nonpolar interaction between Trp19 and Arg22 are probably responsible for the higher structural integrity of the C‐terminal α‐helix over the N‐terminal one. The weaker dielectric constant of longer aliphatic chain length of alcohol possibly reduces the hydrogen bonding between amide protons and surrounding solvent molecules and simultaneously promotes the intramolecular hydrogen bonding in melittin and therefore stabilizes the secondary structure of melittin. The effect of various alcohols on stabilizing melittin is most likely due to their ability to form clusters on the surface of melittin effectively, favoring the formation of intramolecular hydrogen bonds instead of intermolecular hydrogen bonds and promoting the formation of stable α‐helices.     

几种二醇与非质子溶剂相互作用的红外光谱研究

测定了1，2-乙二醇、1，2-丙二醇、1，4-丁二醇和1，6-己二醇在CCl4中分别与十几种非质子溶剂相互作用的红外光谱，通过考察频率位移的变化，定量地研究了二醇分子内氢键与分子间氢键的协同效应．在四氯化碳介质中，乙二醇、1，2-丙二醇和1，4-丁二醇体系中存在明显的氢键协同效应。利用红外光谱数据，估算了常温下二醇分子内缔体与非质子溶剂的交叉缔合常数，其数值大于一元正链醇与相应溶剂的交叉缔合常数．     

丙烯酸甲酯/乙烯基吡啶共聚物铑配合物的配体空间结构对甲醇羰基化反应催化性能的影响

针对共聚物配体聚合的随机性及其共聚结构单元的复杂性 ,运用XPS及红外光谱等分析手段 ,探讨了共聚物铑配合物微观结构对催化性能的影响 ;研究了丙烯酸甲酯 2 乙烯基吡啶和丙烯酸甲酯 4 乙烯基吡啶两种共聚物与铑的不同配比的配合物的活性 ,考察了相同配比的共聚物配合物结构单元、温度等因素对消化活性的影响 ,为催化剂结构的合理设计提供了理论参考     

Carboxylic acid functionalized ortho-linked oxacalix[2]benzene[2]pyrazine: synthesis, structure, hydrogen bond and metal directed self-assembly

Cyclooligomerization of 2,6-dichloropyrazine 4 and benzyl 2,3-dihydroxybenzoate 5 under microwave irradiation resulted in a racemic pair of ester functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 6, which was further transformed to the corresponding racemic carboxylic acid functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 3. Both enantiomers of 3 adopt 1,3-alternate conformations with their two carboxylic acid groups pointing to opposite directions in the solid state. Enantiomers of 3 form a step-like one-dimensional supramolecular polymer via intermolecular hydrogen bond interactions between the carboxylic acids for crystals obtained in methanol. No hydrogen bonds were formed between the carboxylic acids for crystals of 3 obtained in pyridine and aqueous guanidine solutions; instead, intermolecular hydrogen bonds between the carboxylic acid groups of 3 and pyridine, as well as guanidinium ions were formed. Under metal-mediated self-assembly conditions, the pyrazinyl nitrogen atoms in 3 interacted with transition metal ions, such as Ag(I), Cu(II) and Zn(II), and resulted in the formation of four new metal-containing supramolecular complexes. Metallomacrocycles 7, 8 and 9 were formed by reactions of 3 with Ag(I) or Cu(II) ions by bridging two ligands 3 in the equatorial region via M-N coordination bonds. A one-dimensional coordination polymer 10 was generated by reaction between ligand 3 and Zn(II) ions, and a cage-based structure is presented in 10 by bridging of the cyclophane units by Zn(2+) ions via Zn-N and Zn-O bonds.     

Synthesis of dimethyl carbonate by vapor phase oxidative carbonylation of methanol over Cu-based catalysts

Dimethyl carbonate (DMC) synthesis reaction by oxidative carbonylation of methanol has been studied using vapor phase flow reaction system in the presence of Cu-based catalysts. A series of Cu-based catalysts were prepared by the conventional impregnation method using activated carbon (AC) as support. The effect of various promoters and reaction conditions on the catalytic reactivities were intensively evaluated in terms of methanol conversion and DMC selectivity. The morphological analysis by X-ray diffraction and SEM was also conducted in order to characterize the emloyed catalysts. Regardless of catalyst compositions, the optimal reaction temperature for oxidative carbonylation of methanol was found to be around 120–130°C. The reaction rate was too slow below 100°C, while too much by-products was produced above 150°C. Among the various catalysts employed, CuCl₂/NaOH/AC catalyst with the molar ratio of OH/Cu=0.5–1.0, has shown the best catalytic performance, which appears to have a strong relationship with the formation of intermediate species, Cu₂(OH)₃Cl.