The effect of framework functionality on the catalytic activation of supported Pd nanoparticles in the Mizoroki–Heck coupling reaction

Palladium nanoparticles (Pd-NPs) were supported on functional and nonfunctional Co-coordination polymers (Pd/CoBDCNH₂ and Pd/CoBDC). Advanced analytical techniques revealed that Pd-NPs are supported on the external surface of the polymer framework and the functionalized framework possesses effective influence to prevent Pd-NP aggregation. Supported Pd-NPs were effectively applied as heterogeneous recyclable catalysts in the Mizoroki–Heck C–C cross coupling reactions of iodobenzene and either aromatic or aliphatic terminal alkenes. Catalytic results exhibited that highly dispersed Pd-NPs with low loading (1%) on the functional polymer (Pd/CoBDCNH₂) are more effective than aggregated Pd-NPs with high loading (9%) on the nonfunctional polymer (Pd/CoBDC). Both catalysts can simultaneously provide high activity and selectivity to E-coupled products, high efficiency in low amounts, easy separation of heterogeneous catalyst and appropriate performance in the recycling reaction without addition of a reducing agent.     

The influence of matrix structure on the activity and selectivity of polymer supported catalysts

The influence of the pore structure, surface area, crosslinking density and the distribution of catalytic groups on the activity / selectivity of polymer supported catalysts was investigated. As model catalysts a variety of styrene-divinylbenzene-copolymers functionalized with sulfonic acid groups were used. The isomerization of 1-butene and the cleavage of methyl tert - butyl ether (MTBE) were studied as gas phase reactions in the presence of the acid resins. The activity and selectivity was controlled by the acidity and accessibility of the polymer supported catalyst.     

负载型催化剂的表面相互作用及其在大气分子污染物NO和CO消除中的应用基础研究

负载型催化剂具有重要的应用背景,研究表面分散组分与载体之间的相互作用.对于了解催化过程的本质,进而设计开发高效实用的催化剂均有重要的指导意义.本课题组近年来在该领域中进行了一些探索研究,涉及的催化剂以负载型金属氧化物(如CuO/γ-Al_2O_3,CuO/Ce_xZr_(1-x)O_2和CuO/Ti_xSn_(1-x)O_2等)为主,涉及的反应包括CO完全氧化和NO+CO反应.通过改变活性组分的负载量、添加改性剂和改变样品制备条件等制得一系列样品,用多种固体催化剂表征手段考察各组分在催化剂中的作用以及在上述催化反应中的活性变化规律.研究表明:(1)金属氧化物和卤化物等离子化合物在氧化物载体表面的分散容量和分散后的一些性质均可从"嵌入模型"的考虑得到解释;(2)处于不同载体表面的活性物种或同一载体表面不同结构的活性物种,由于其存在状态的差异使得其氧化还原性质和催化性质不同;(3)在相关催化剂体系中进行的CO完全氧化和NO+CO反应的结果显示,通过探索催化剂的"组成-结构-性质"间的关系,有可能为实际催化剂的设计提供理论参考.     

In Situ Formation of Gold Nanoparticles within a Polymer Particle and Their Catalytic Activities in Various Chemical Reactions

Composite materials consisting of nanoscale gold particles and protective polymer shells were designed and tested as catalysts in various chemical reactions. Initially, the systematic incorporation of multiple gold nanoparticles into a poly(N-isopropylacrylamide) particle was achieved by an in situ method under light irradiation. The degree of gold nanoparticle loading, along with the structural and morphological properties, was examined as a function of the amount of initial gold ions and reducing agent. As these gold nanoparticles were physically-embedded within the polymer particle in the absence of strong interfacial interactions between the gold nanoparticles and polymer matrix, the readily-accessible surface of the gold nanoparticles with a highly increased stability allowed for their use as recyclable catalysts in oxidation, reduction, and coupling reactions. Overall, the ability to integrate catalytically-active metal nanoparticles within polymer particles in situ allows for designing novel composite materials for multi-purpose catalytic systems.     

Ethylene polymerization studies with supported cyclopentadienyl,arene, and allyl chromium catalysts

Highly active catalysts for low pressure ethylene polymerization are formed when chromocene, bis (benzene)- or bis (cumene)-chromium or tris- or bis (allyl)-chromium compounds are deposited on high surface area silica-alumina or silica supports. Each catalyst type shows its own unique behavior in preparation, polymerization, activity, isomerization, and response to hydrogen as a chain transfer agent. The arene chromium compounds require an acidic support (silicaalumina) or thermal aging with silica to form a highly active catalyst. At 90°C polymerization temperature arene chromium catalysts produced high molecular weight polyethylene and showed, in contrast to supported chromocene catalysts, a much lower response to hydrogen as a chain transfer agent. An increase in polymerization temperature caused a significant decrease in polymer molecular weight. Addition of cyclopentadiene to supported bis (cumene)-chromium catalyst led to a new catalyst which showed a chain transfer response to hydrogen typical of a supported chromocene catalyst. Polymerization activity with tris- or bis (allyl)-chromium appears to depend on the divalent chromium content in the catalyst. Changes in the silica dehydration temperature of supported allyl chromium catalyst have a significant effect on the resulting polymer molecular weight. High molecular weight polymers were formed with catalysts that were prepared using silica dehydration temperatures below about 400°C. Dimers, trimers, and oligomers of ethylene were usually formed with catalysts that were prepared on silica dehydrated much above 400°C. The order of activity of the different types of catalysts was chromocene/silica > chromocene/silica-alumina > bis (arene)-chromium/silica-alumina ? allyl chromium/silica.     

Hydrogenating Activity and Adsorption Capacity of Supported Nickel Catalysts Modified by Heteropoly Compounds

The catalytic activity, adsorption capacity, and pore structure of low-percentage nickel catalysts supported on -Al₂O₃or activated carbon and modified by tungsten heteropoly compounds are studied. The activity, selectivity, and thermal stability of the catalysts in the vapor-phase hydrogenation of olefins and aromatic hydrocarbons are higher than those for conventional nickel catalysts. The concentration of nickel in the catalysts is 10–15 times lower than that in commercial catalysts. However, the modified catalysts have higher specific surface areas of metal, higher dispersion, a uniform distribution of metal particles, and a pore-radius distribution other than in the support. The study of water adsorption and desorption showed that the heteropoly compound modifying the -Al₂O₃support covers the support surface completely, and supported nickel interacts with the active surface of the modifying agent rather than with Al₂O₃. A hydrogenation mechanism is proposed, which involves H₂dissociation on Ni particles and the subsequent diffusion of hydrogen atoms via a spillover mechanism to the adsorbed organic compound with the participation of the OH groups of the modifying agent.     

负载钯催化的Suzuki偶联反应研究进展

负载钯催化的Suzuki偶联反应,由于产物易分离、催化剂可重复使用,已引起人们的广泛关注.综述了近年来负载钯催化的Suzuki偶联反应研究进展,载体包括活性碳、金属氧化物、硅铝酸盐微孔分子筛、二氧化硅材料、活性粘土和聚合物等.     

Polymer supported copper(II) amine‐imine complexes in the C‐N and A3 coupling reactions

New polymer supported Cu(II) complexes based on an epoxy functionalized gel type resin were prepared using the multi‐stage procedures. The reactions of epoxy groups with ethylenediamine or tris(2‐aminoethyl)amine, and then NH₂ groups with salicylaldehydes were used for the preparation of a series of amine‐imine functionalized polymer supports. Copper(II) acetate was used as a source of metal ions. The complexes were characterized using ICP‐OES, FTIR, DR UV–Vis and TGA techniques, and tested as catalysts in two model C‐N and a series of A³ coupling reactions. Their catalytic activity was rather low in the C‐N coupling reactions between imidazole and iodobenzene or phenylboronic acid. However, the second of the reactions could be conducted effectively under milder conditions. The complexes were efficient used as recyclable catalysts in the A³ coupling reactions. A series of aromatic aldehydes and secondary amines and phenylacetylene could be coupled using 1% mol catalyst.     

高分子离子液体的研究进展

综述了高分子离子液体最新的研究进展。作为离子液体的载体材料主要有两大类 :一是无机高分子 ,离子液体中的阴离子或阳离子通过与无机高分子材料表面的基团键合形成含离子液体结构的高分子 ;二是有机高分子 ,在有机高分子上引入离子液体合成聚合物电解质 ,并介绍了其在催化、导电材料方面的应用前景     

Efficient Synthesis of α,β‐Epoxy Carbonyl Compounds in Acetonitrile: Darzens Condensation of Aromatic Aldehydes with Ethyl Chloroacetate

The Darzens reaction of ethyl 2‐chloroacetate ( 1 ) with aromatic aldehydes 2 in the presence of polymer‐supported or nonsupported quaternary ammonium salts proceeds under mild conditions by phase‐transfer catalysis to give the corresponding epoxides 3 in satisfactory yields (Tables 1 and 2). With both MeCN as solvent and polystyrene‐supported catalysts, diastereoselective Darzens reactions proceed in excellent yields and short times, with a fair degree of stereoinduction.     

用乙酰氯淬灭法测定Ziegler-Natta催化剂的活性中心数

在测定Zieler-Natta催化剂活性中心数的主要方法中,动力学-分子量法不能测定聚合中任意时刻的活性中心数,氚醇淬灭法、阻聚法及~(14)CO标记法等的可靠性尚未得到充分肯定,因而有必要寻找兼具可靠、方便及适用面广等特点的新测定方法。本文报道用乙酰氯作为一种新的淬灭剂测定TiCl_3-烷基铝催化1-辛烯聚合体系活性中心数的初步结果。     

“嵌入模型”在γ-Al2O3负载单组分和双组分金属氧化物催化剂中的应用

探讨负载型金属氧化物催化剂的表面组分与载体之间的相互作用, 有助于理解相关催化剂的催化作用本质. 近年来, 我们对单组分CuO以及双组分CuO-Mn₂O₃, CuO-CoO等金属氧化物在γ-Al₂O₃载体表面的分散行为和存在状态, 及其物理化学性质和催化性能(CO+O₂和NO+CO模型反应)进行了研究. 结果表明, 这些金属氧化物在γ-Al₂O₃载体表面的分散行为和所得负载型催化剂样品的一些物理化学性质及其催化性能均可参照“嵌入模型”来解释. 在此基础上, 我们讨论了这些样品的“组成-结构-性质”间的关系, 并针对表面负载双组分金属氧化物样品提出了表面协同氧空位参与的NO+CO反应机理.     

Solid Phase Catalytic Oxidation of Alcohols by Polymer Supported Rare Earth Catalysts

Oxidation of alcohols to the corresponding aldehydes or ketones is one of the most fundamental reactions in organic chemistry [1,2]. Some of the products of the oxidation exhibit an important role in the organic synthesis as well as pharmaceutical synthesis. In most reactions, the lanthanide complexes show satisfied catalytic activities for some compounds. Furthermore, there has been increasing interest in the lanthanide complexes and several reports have appeared in the literature [3, 4]. But the exploitation of these complexes for the oxidation of some organic substrates has been limited. Here we reported a method for the preparation and the catalytic properties as well as the recycling of lanthanide complexes in oxidation of alcohols.The synthetic procedure for the polymer supported lanthanide complexes is shown as following(scheme 1):●-NH2+CICH2COOH(C2Hs)3N→●-NHCH2COOHM=Ce(Ⅲ), Tb(Ⅲ), Sm(Ⅲ)scheme 1The oxidation of benzyl alcohol was carried out in the presence of iodosylbenzene by the polymer supported Ce(Ⅲ), Tb(Ⅲ) and Sm(Ⅲ) catalysts at 80℃ for 4.0h, the yields of benz-aldehyde are as following (table 1):Table 1 Oxidation of benzyl alcohol with the supported catalysts**Reaction condition: benzyl alcohol 0.1 mmol, iodosylbenzene 0.15mmol,catalyst 0.2mg, 80℃ for 4.0h in 1,2-dichloroethane.It can be seen from the table that the Tb(Ⅲ) complex shows higher catalytic activity for the oxidation of benzyl alcohol. Further investigation is now being carded on to optimize the results.     

Morphology Evolution in the Early Stages of Olefin Polymerization

The olefin polymerizations were carried out by using silica supported metallocene/MAO catalysts and MgCl₂ supported Ziegler-Natta catalysts under mild reaction conditions and stopped at very low yield. The surface and cross sectional morphology of the polymer particles were characterized by using scanning electron microscopy (SEM). A homogeneous distribution of (co)catalyst on the support material is a prerequisite condition to get a homogeneous fragmentation and uniform polymer particle morphology. In the present work the catalysts show two different fragmentation behaviors. They can gradually fragment from the outer to the inner surface of the catalyst particle, or instantaneously break up into a large amount of small sub-particles at the beginning of the polymerization. The incorporation of comonomer does not change the general catalyst fragmentation scheme but delays the catalysts break-up progress.     

在杂多酸催化剂上苯和1-十二烯烷基化合成十二烷基苯

对不同ＳｉＯ２负载磷钨酸（ＰＷ）催化剂的表面性质、热稳定性、酸性、以及对苯与丙烯和１－十二烯的烷基化反应的催化活性进行了对比研究,结果表明,ＰＷ在ＳｉＯ２上的分散状况与ＳｉＯ２的比表面积和孔径大小有关,ＰＷ与载体表面作用的强弱会直接影响负载型催化剂的热性和酸性,采用不同的ＳｉＯ２可以制得比表面积、孔结构和酸强度不同的负载型ＰＷ催化剂,以满足不同催化反应的要求。     

STUDY ON POLYMER—Ru-Co—BIMETALLIC COMPLEXES CATALYSTS Ⅰ. SYNTHESIS OF CATALYSTS AND THEIR USE FOR THE HYDROFORMYLATION

Six kinds of polymer ligands, supported on SiO_2, containing coordinating atoms P, S and N respectively, have been synthesized. The Ru(Ⅲ)-Co(Ⅱ) bimetallic complexes of these polymer ligands have been obtained and examined as catalysts for the hydroformylation of cyclohexene. The effects of reaction temperature, pressure and Co/Ru ratio etc. on the activities of catalysts were investigated in detail. The catalysts are all polymer-noncarbonyl-metal complexes, easily to be prepared, active and stable. From the experimental results it can be suggested that under reaction conditions such polymer-noncarbonyl-metal complexes convert "in situ" to polymer-carbonyl-metal complexes, thus become active catalysts. The course of this conversion is supposed as a preliminary approach.     

STUDIES ON TiCI4/Mg (OEt)_2/EB SUPPORTED CATALYSTS FOR PROPYLENE POLYMERIZATION

The supported catalysts for propylene polymerization were prepared by milling Mg (OEt)_2 with EB (ethylbenzoate) and treating with TiCl_4 solution. When TiCl_4/(Mg(OEt)_2/EB) (mol.) ratio was increased, decrease in contents of-OEt and Ti of the catalysts was observed, while the content of EB increased. It is proved by analyses of IR, X-ray and XPS that during co-milling Mg(OEt)_2 with EB no reactions have taken place. But after treatment with TiCl_4 solution, Mg(OEt)_2 converts into MgCl_2 and EB coordinates on the resulting MgCl_2 carrier, a surface complex forms.The activity of catalysts,isotacticity and vicosimetric molecular weight of polypropylene increase with the decrease of the content of ethoxyl group. The kinetic curves of propene polymerization obtained with present catalysts system display decay curves. It is found from the triad tacticity calculated from the expanded spectra of methyl carbon region that, ethoxyl group in catalyst has an effect on the configuration of polymer chain.     

高分子支载的手性催化剂在不对称有机反应中的应用进展

本文评述了近年来高分子支载的手性催化剂在不对称氢化、不对称还原、不对称烷基化、不对称Ｄｉｅｌｓ－Ａｌｄｅｒ加成以及不对称二羟基化等有机反应中的应用进展。     

Ionic‐Liquid‐Grafted Rigid Poly(p‐Phenylene) Microspheres: Efficient Heterogeneous Media for Metal Scavenging and Catalysis

Novel guanidinium ionic liquid‐grafted rigid poly(p‐phenylene) (PPPIL) microspheres have been developed for metal scavenging and catalysis. The noble‐metal nanoparticles supported on the microspheres surface can be used as efficient heterogeneous catalysts. The combination of nanoparticles and ionic liquid fragments on the microsphere surfaces enhance the activity and durability of the catalyst. The PPPIL ? Pd⁰ catalyst has been tested in the Suzuki cross‐coupling reaction, and exhibits much higher catalytic activity than Pd catalysts supported on porous polymer matrices. The PPPIL ? Pd⁰ catalyst can be recycled at least for nine runs without any significant loss of activity. The present approach may, therefore, have potential applications in transition‐metal‐nanocatalyzed reactions.     

固体碱上硫醇氧化反应中助剂的作用

采用微波分散MgO的方法制备固体碱以替代脱硫醇反应中常用的液体碱，其制水冲刷性有利于延长固体碱催化剂的寿命。使用甲醇和含表面活性剂助剂能明显提高催化剂的活性。采用吸光光度法监测反应体系，发现助剂的加入可以加大活性组分磺化酞菁钴（CoPcS)在,催化剂表／界面水相中的溶解度；而紫外光谱的研究进一步证实了甲醇可以防止CoPcS分子间的二聚，促进活性组分的高分散。