(Salen)Ti~(Ⅳ)Cl_2配合物催化环氧化物和环酸酐开环交替共聚

合成、表征了一类具有salen型配体骨架的Ti~(Ⅳ)配合物(Salen)Ti~(Ⅳ)Cl_2,并研究了它们在催化环酐/环氧开环交替共聚合时的催化性能与催化行为.这些配合物在结构上与传统的(Salen)M~(Ⅲ)Cl配合物(M=Al,Co和Cr)不同,在配位平面的轴向有2个Cl~-基团,不存在空的配位点.以双(三苯基膦)亚胺氯化物(PPNCl)为助催化剂,(Salen)Ti~(Ⅳ)Cl_2配合物可以有效催化常见环酸酐和环氧化物的开环交替共聚合,生成具有完美交替结构的聚酯.聚合活性取决于Salen-Ti~(Ⅳ)配合物路易斯酸性、配体骨架和单体结构.初步的链引发反应机理研究表明,(salen)Ti~(Ⅳ)Cl_2配合物中的轴向Cl~-基团可与助催化剂中的阴离子发生配体交换而引发聚合反应.     

交联聚苯乙烯微球固载的双齿席夫碱型氧钒(Ⅳ)配合物催化分子氧氧化苯甲醇

利用水杨醛(SA)和氨甲基(MA)交联聚苯乙烯(CPS)微球反应,制得键合有双齿席夫碱配体SAAM的交联聚苯乙烯SAAM-CPS微球,再与硫酸氧钒发生螯合配位反应,制备了固载有席夫碱型氧钒(Ⅳ)配合物催化剂,采用红外光谱、扫描电镜及热失重等手段对催化剂进行了表征,并用于催化分子氧氧化苯甲醇反应,考察了催化剂用量、反应温...     

膦基苯磺酸(PO)金属配合物催化乙烯与极性单体的共聚反应及其机理研究进展

含有膦基苯磺酸(PO)配体的烷基金属配合物表现出罕见的烯烃聚合催化性质,其不但可以催化乙烯均聚形成线性聚乙烯,而且可以催化乙烯与众多的极性单体如CH2=CHX、CO等共聚产生功能化线性聚烯烃.总结了PO配体的结构特点和(PO)Pd(Ⅱ)配合物引发的新型聚合反应,综述了(PO)Ni(Ⅱ)催化剂在催化乙烯和极性单体共聚方面的应用,以及含有膦基二磺酸配体OPO的Pd(Ⅱ)、Ru(Ⅳ)催化剂的特殊催化性质.另外,从配体的对称性、柔性和轴向官能团位阻以及纯电子效应等方面对PO金属催化剂的构效关系和共聚催化反应机理进行了探讨.     

同核双金属烯烃聚合催化剂

与单核金属配合物催化剂相比,双核金属配合物催化剂所具的双金属活性中心对烯烃聚合催化活性和所得聚合物的性能(包括聚合物微结构、分子量大小和分子量分布)产生了重要影响。本文综述了双金属配合物作为均相催化剂催化乙烯聚合及共聚合的最新研究,归纳思路包括不同的金属类型,即基于前过渡金属(Zr, Ti, Hf) 和后过渡金属(Ni, Fe, Co) 的双核金属组合; 不同的配体化合物,即CGC配体、酚氧亚胺配体、氮杂环胺配体、α-二亚胺和亚胺吡啶配体等。这些研究表明,前过渡金属催化剂不仅解决了乙烯自聚还实现了乙烯与α-烯烃共聚;后过渡金属催化剂高效催化乙烯自聚合,其中铁和钴催化剂获得高度线性聚乙烯,镍催化剂则产生多支链聚乙烯。     

聚合物载体上功能基配体对不同催化活性物种氢甲酰化催化性能的影响

作者用五类聚合物配体与不同催化活性物种反应制备了负载催化剂,并考察了聚合物配体及聚合物载体上功能基(配体)对不同催化活性物种氢甲酰化催化性能的影响。实验结果表明:当聚合物配体相同时,Co_2Rh_2(CO)_(12)双金属簇催化活性物种优于RhCl_3·3H_2O及Rh_2(Co)_4Cl_2;聚(N——乙烯基吡咯烷酮)(PNVP)及马来酸酐与苯乙烯共聚物(PMAn)负载催化剂大多具有良好的氢甲酰化催化性能。     

膦配体链长对锚合膦配体修饰的Rh/SiO_2催化剂上氢甲酰化反应性能的影响(英文)

烯烃氢甲酰化反应产物醛是生产多种有机化合物的重要中间体,具有重要的工业价值.均相催化剂具有反应条件温和及催化效率高的优点,因而成为工业应用的主要催化体系,但催化剂分离复杂且昂贵.多相催化剂具有易分离和易回收的优点,但在氢甲酰化反应中的活性和选择性较低,因而大大阻碍了其在工业上的应用.为了得到兼具两种催化剂优点的新型催化剂,人们进行了数十年的研究,均相催化剂多相化便是其中一个研究热点.实现该策略最常用的一个方法是将均相催化剂固载到载体上,以此来达到催化剂易从反应物及产物中分离,同时保有高活性高选择性的目的.通过化学键将金属配合物的配体键合到载体上已经取得了一定的成功,但依然存在着活性组分流失和催化剂失活的问题.本课题组开发了一种锚合膦配体修饰的Rh/SiO_2新型催化剂,在乙烯氢甲酰化反应中表现出卓越的稳定性,反应1000 h后依然没有出现活性下降和组分流失的现象,这是因为配体和活性金属同时被固载在载体SiO_2上.但是由于配体和活性金属都不能自由移动,很多配体不能与金属原子有效接触,起不到配位效应,因而催化剂活性仍不够高.因此,为了提高锚合膦配体修饰的Rh/SiO_2催化剂的活性,我们合成了具有较长链长的膦DPPPTS,并与商业购买的链长较短的膦DPPETS做对比,研究锚合膦配体链长和催化剂活性的关系.使用N_2物理吸附、原位红外光谱(FT-IR)和固体~(31)P核磁共振(NMR)等探讨了膦配体链长影响催化性能的原因.固定床上乙烯氢甲酰化反应结果表明,当膦配体的链长增长一个亚甲基长度后,反应稳定后催化剂的活性提高了一倍以上.N_2物理吸附实验表明,延长配体的链长对催化剂结构性质的影响不大,因而也不会改变反应时的传质.催化剂吸附合成气(CO:H_2=1:1)的原位FT-IR结果表明,不同链长膦配体修饰的Rh/SiO_2催化剂上均原位生成了类似于用于均相氢甲酰化反应的Wilkinson型催化剂的活性物种HRh(CO)_2(DPPPTS)_2[或HRh(CO)_2(DPPETS)_2],以及吸附在Rh上的线式CO.这两种吸附物种均利于氢甲酰化反应的进行,其中以前者活性更好.从原位FT-IR结果同样看出,锚合链长较长的膦配体的催化剂(DPPPTS-Rh/SiO_2)上原位生成的活性物种量更多,因而催化活性更高.固体~(31)P NMR结果表明,催化剂上的膦以自由态的膦(高场峰β)和与Rh配位的膦(低场峰α)两种形式存在.α峰面积和β峰面积之比(r)越高代表与Rh配位的膦配体占总膦量的比例越高.发现DPPPTS-Rh/SiO_2催化剂的r值(1.31)高于DPPETS-Rh/SiO_2催化剂(1.05),即前者与Rh配位生成活性物种的膦配体的比例更高.结合原位FT-IR和固体~(31)P NMR的结果可知,链长较长的DPPPTS更容易与Rh配位,从而生成更多的铑膦配合物活性物种,因而催化剂活性更高.因此,增长锚合膦配体的链长有助于提高其修饰的Rh/SiO_2催化剂的活性.     

溴化钯或乙酰丙酮羰基铑/手性配体催化醛与乙酰胺的不对称酰胺羰化反应研究

采用溴化钯为催化剂前体,与非螯合型双齿膦配体L1(DPPFF)、联吡啶型双齿膦配体L2(P-PHOS)和二茂铁基手性双膦配体L3((S,Rp)-BPPF)制备络合物催化剂,以乙酰丙酮羰基铑为催化剂前体,与手性亚磷酸酯配体L4-L6制备络合物催化剂,将其分别应用于底物环己基甲醛或苯乙醛的不对称酰胺羰化反应中,研究结果表明...     

第ⅣB族非茂金属烯烃聚合催化剂

烯烃聚合催化剂技术的发展关系着聚烯烃工业的命脉,而第ⅣB族非茂金属烯烃聚合催化剂作为目前催化剂研究的热点之一,不仅具有催化活性高、共聚单体范围广以及聚合物结构可控等优点,并且相比于茂金属催化剂而言,合成简单、成本低廉,有利于丰富烯烃聚合催化剂的种类和开发新型聚烯烃产品。本文按照配体的价齿类型综述了近十年来第ⅣB族非茂金属烯烃聚合催化剂的结构特点,及其在烯烃均聚和共聚反应中的催化性能,讨论了配体的电子效应和位阻效应对于配合物催化活性以及所得聚合物的结构、分子量等性质的影响,并对相关领域的未来发展提出了建议。     

负载型钴二亚胺配合物-TiCl_4复合催化剂制备新型乙烯/1-丁烯共聚产物结构性能研究

合成了三种负载型二亚胺配体钴配合物 TiCl4复合催化剂 (CL1、CL2、CL3催化剂 ) .不用MAO ,以烷基铝为助催化剂 ,用它们催化乙烯 1 丁烯淤浆共聚合制备一系列塑性体和弹性体共聚物 .研究表明 ,复合催化剂性质受二亚胺配体性质影响 ,配体L1制备的复合催化剂具有低聚及原位共聚性能 ,可制得高支化度(36 0～ 6 1 5branchnumber 10 0 0C)低密度和极低密度 (0 885～ 0 910g cm3)塑性体和弹性体共聚物 .在 1 丁烯用量低于 5 %时 ,CL1催化剂制备的共聚产物中 1 丁烯含量超过投料比     

不同配体的稀土金属配合物在烯烃聚合领域的研究进展

催化剂在推动聚烯烃工业发展中有着举足轻重的作用,其中金属催化剂的设计与合成更是金属有机催化化学的关键.稀土金属具有独特的轨道结构、反应活性和配位准则,因此稀土金属配合物通过在金属中心周围引入空间位阻,在聚烯烃材料制备中表现出独特优势.其中配体是决定稀土金属配合物的结构、化学活性及稳定性等方面的关键因素.本综述介绍了茂基配体(烷基取代、芳基取代、茚和芴配体)和非茂基配体(大环四齿配体、三齿配体、双齿配体和单齿配体)的稀土金属配合物的发展及其在聚烯烃制备中的应用.这项工作旨在促进稀土金属催化剂在聚烯烃催化和金属有机催化领域的研究,为高端化、差异化聚烯烃聚合催化剂的制备提供新的设计思路和研究方法.     

碳笼烯-60对Ziegler-Nata催化剂催化苯乙烯聚合的影响

碳笼烯 ６０对Ｚｉｅｇｌｅｒ Ｎａｔａ催化剂催化苯乙烯聚合的影响洪瀚周锡煌李福绵（北京大学化学学院北京１００８７１）关键词碳笼烯 ６０（Ｃ６０），Ｚｉｅｇｌｅｒ Ｎａｔａ催化剂，配位聚合，等规聚苯乙烯Ｃ６０独特的球笼形空间结构和电子结构决定了其有许...     

Synthesis, characterization, and catalytic application of PbS nanoparticles for the synthesis of amidoalkyl naphthols under solvent-free conditions

A simple one-pot synthesis has been developed for the synthesis of amidoalkyl naphthols using an efficient and recyclable nanocrystalline PbS catalyst under solvent-free condition. Using this nanocrystalline solid catalyst, the reactions could be carried out under mild reaction conditions with very good yield (85–95 %). This catalyst could be recycled very easily, which makes this methodology environmentally benign. The biologically active drug-like molecule 1-aminomethyl-2-naphthol derivatives can be easily obtained from 1-amidomethyl-2-naphthol by amide hydrolysis reaction in the presence of PbS nanoparticles. Characterization of the catalyst was performed by X-ray diffraction, transmission electron microscopy, and adsorption/desorption analysis (BET).     

醚酞络合物的分子结构和晶体结构

醚类会被广泛用来改性Ziegler-Natta催化剂,如著名的Solvay型催化剂就是用异戊醚处理β-TiCl_3,国内研制的所谓络合Ⅰ型,或络合Ⅱ型催化剂则是用异戊醚或正丁醚作为络合剂。乙醚与四氯化钛的反应物对3TiCl_3·AlCl_3催化剂有显著的改进,给电子体醚可使铝在催化剂表面富集。因而研究醚与四氯化钛或三氯化钛络合物的结构是一个基本的问题。已知四氯化钛和醚可生成多种络合物,但其分子结构及晶体结构测定甚少,本     

Phosphabenzenes as monodentate pi-acceptor ligands for rhodium-catalyzed hydroformylation

A new class of phosphinine/rhodium catalysts for the hydroformylation of terminal and internal alkenes is presented in this study. A series of phosphabenzenes 1-14 has been prepared by condensation of phosphane or tris(trimethylsilyl)phosphane with the corresponding pyrylium salt. Trans-[(phosphabenzene)2RhCl(CO)] complexes 21-25 have been prepared and studied spectroscopically and by X-ray crystal-structure analysis. The hydroformylation of oct-1-ene has been used to identify optimal catalyst preformation and reaction conditions. Hydroformylation studies with 15 monophosphabenzenes have been performed. The catalytic performance is dominated by steric influences, with the phosphabenzene 8/rhodium system being the most active catalyst. Turnover frequencies of up to 45370 h(-1) for the hydroformylation of oct-1-ene have been determined. In further studies, hydroformylation activity toward more highly substituted alkenes was investigated and compared with the standard industrial triphenylphosphane/rhodium catalyst. The reactivity differences between the phosphabenzene and the triphenylphosphane catalyst increase on going to the more highly substituted alkenes. Even tetrasubstituted alkenes reacted with the phosphabenzene catalyst, whereas the triphenylphosphane system failed to give any product. In situ pressure NMR experiments have been performed to identify the resting state of the catalyst. A monophosphabenzene complex [(phosphinine 8)Ir(CO)3H] could be detected as the predominant catalyst resting state.     

Highly enantioselective Friedel-Crafts reaction of aromatic amines with ethyl glyoxylate catalyzed by chiral titanium(IV) complexes: practical synthesis of aminomandelic acid derivatives

The asymmetric Friedel-Crafts reaction of a variety of N,N-dialkylanilines with ethyl glyoxylate has been achieved by the catalysis of titanium complexes of BINOL derivatives to give corresponding ethyl esters of p-N,N-dialkylaminomandelic acids in high yields (85-99%) and good to excellent enantioselectivities (80-96.6% ee) under the optimized reaction conditions, which has added a new catalyst for this class of reactions. The reaction could also be carried out at a reduced catalyst loading (1 mol %) in gram scale, which provided a practical synthesis of enantiopure aminomandelic acid derivatives.     

MgCl(2).6PhCH2OH--a new molecular adduct as support material for Ziegler-Natta catalyst: synthesis, characterization and catalytic activity

Benzyl alcohol has been used to prepare a single phase MgCl(2).6BzOH molecular adduct as a support for an ethylene polymerization catalyst (Ziegler catalyst). The structural, spectroscopic and morphological aspects of the MgCl(2).6BzOH molecular adduct and the Ziegler catalyst have been thoroughly studied by various physicochemical characterization techniques. The presence of MgO(6) octahedrons due to the interaction of Mg(2+) with six -OH groups of the benzyl alcohol is confirmed from a Raman feature at 703 cm(-1), and structural studies. The supported catalyst activity has been evaluated for the ethylene polymerization reaction. The lower polymerization activity of the titanated Ziegler-Natta catalyst compared with a standard catalyst is attributed to the strong interaction of titanium chloride with the support and associated electronic factors.     

Synthesis of well-defined head-to-tail-type oligothiophenes by regioselective deprotonation of 3-substituted thiophenes and nickel-catalyzed cross-coupling reaction

Iterative growth of thiophene oligomers by single-step extensions has been realized by regioselective metalation of 3-substituted thiophenes with the Knochel-Hauser base (TMPMgCl·LiCl) and coupling with bromothiophene using a nickel catalyst. Treatment of 3-hexylthiophene with TMPMgCl·LiCl induces metalation at the 5-position selectively. Subsequent addition of 2-bromo-3-hexylthiophene and a nickel catalyst leads to the corresponding bithiophene. The obtained bithiophene is converted to the terthiophene and then to the quaterthiophene by repeating the similar protocol. A concise synthesis of MK-1 and MK-2, which are organic dye molecules bearing an oligothiophene moiety that are used in photovoltaic cells, has been achieved.     

Development of highly diastereo- and enantioselective direct asymmetric aldol reaction of a glycinate Schiff base with aldehydes catalyzed by chiral quaternary ammonium salts

A highly efficient direct asymmetric aldol reaction of a glycinate Schiff base with aldehydes has been achieved under mild organic/aqueous biphasic conditions with excellent stereochemical control, using chiral quaternary ammonium salt 1b as a phase-transfer catalyst. The initially developed reaction conditions, using 2 equiv of aqueous base (1% NaOH (aq)), exhibited inexplicably limited general applicability in terms of aldehyde acceptors. The mechanistic investigation revealed the intervention of an unfavorable yet inevitable retro aldol process involving the chiral catalyst. On the basis of this information, a reliable procedure has been established by use of a catalytic amount of 1% NaOH (aq) and ammonium chloride, which tolerates a wide range of aldehydes to afford the corresponding anti-beta-hydroxy-alpha-amino esters almost exclusively in an essentially optically pure form.     

铑配合物催化甲醇羰基化反应的性能和机理

本文合成了２－丁酸甲酯吡啶与四羰基二氯二铑形成的螯合形配合物，并用Ｘ射线光电子能谱（ＸＰＳ），红外光谱（ＩＲ）及核磁共振（ＮＭＲ）研究确定了其配位结构特征，通过甲醇羰基化制备乙酸的反应揭示了其结构特征对催化剂活性及稳定性的影响，并提出了可能的反应机理。