高分子催化剂对羧基还原加氢的研究

一般的羧基加氢成羟基反应需要在较高的温度和压力下进行,寻找理想的加氢催化剂是许多科学工作者的奋斗目标.从六十年代末开始,人们将金属化合物络合在高分子配体上,形成高分子金属络合物来作为催化剂,这类催化剂具有高活性、高选择性,便于回收、使用、反应条件温和等特点.高分子金属络合物的催化活性,不仅取决于催化金属活性中心,而且强烈地依赖于高分子配体的种类和性质,这是由于高分子催化剂的分子链中诸功能基之间存在着协同效应.有的具有光学活性等特殊结构,使其具有高的催化活性和选择性.     

高分子负载催化剂的应用研究进展

高分子负载催化剂具有稳定性高、溶剂适用性广、易于产物分离纯化、对环境影响小、易从反应体系中分离回收和重复使用等优点,受到人们极大的重视。从高分子负载催化剂的特点、种类等方面综述了高分子负载催化剂不同于低分子金属络合物的催化性能,以及其应用进展。     

离子交换树脂负载的钯络合物催化油脂加氢

近年来,高分子固载化金属络合物催化剂以其优异的性能引起了催化工作者的广泛重视,做了大量的研究工作。但大部分是侧重于对共价键联高分子催化剂的研究,对离子键合形式的研究较少。离子交换树脂价廉易得,机械强度好且为球状颗粒,易于回收再用,是一种理想的高分子催化剂载体。本文中用几种不同功能基的离子交换树脂作载体制备了相应的高分子钯络合物催化剂,并检验了其对棉籽油加氢的活性和选择性。考察了反应条件对加氢速度的影响,所得结果对高分于催化剂的工业化应用有一定的意义。     

高分子负载钯催化Suzuki反应的研究进展

高分子负载钯催化剂与均相催化剂相比易于分离、可重复使用,同时大多数高分子负载钯催化剂保留了较高的催化活性。高分子负载钯催化剂已成为Suzuki反应催化剂的研究热点之一。本文综述了近年来高分子负载钯络合物及钯纳米催化剂在Suzuki反应中的研究进展。     

树脂固载钯络合物对油脂催化加氢性能及其动力学研究

本工作以强碱性阴离子交换树脂作载体制备了相应的高分子钯络合物催化剂,检验了其对棉籽油加氢的活性和选择性,考查了不同制备条件对催化剂活性的影响,求出其催化加氢的表现动力学方程为:r=KPH_2 近年来,高分子固载金属络合物催化剂以其优异的性能,引起了人们广泛的重视,做了大量的研究工作。但大部分着眼于共价键联高分子催化剂的研究,而对离子键合形式研究较少。离子交换树脂合成方便,原料易得,机械强度好且为球状颗粒易于回收再用,是一种理想的高分子催化剂载体,制备了高分子—钯络合物催化剂,考察了所得催化剂对棉籽油的催化加氢性能及其表观动力学行为。     

乙苯催化氧化合成苯乙酮研究进展

综述了乙苯催化氧化合成苯乙酮的研究进展,介绍了杂多化合物、过渡金属络合物、金属原子簇化合物、金属卟啉化合物及分子筛催化剂对乙苯选择氧化反应的催化效果和特点。结果表明,钼钒磷杂多化合物及钴络合物是乙苯催化氧化反应的理想催化剂,具有良好的应用前景。     

多相铂催化剂在芳香族化合物加氢中的应用

介绍了负载型铂催化剂、高分子铂络合物催化剂和负载型含铂双金属催化剂等几种多相铂催化剂在芳香族化合物加氢中的应用及各自特点，展示这类催化剂在反应中具有良好的催化活性。     

用聚γ-二苯基膦丙基硅氧烷-铂络合物催化的芳香族化合物的加氢

与烯烃的加氢相比,苯环的加氢需要较激烈的反应条件。虽然已有很多可用于芳香族化合物加氢的多相催化剂,但大部分的催化活性和选择性较低。最近发现有一些有机金属络合物,如(η~3-C_3H_5)Co[P(OMe)_3]_3、[Rh(η~5-C_5Me_5)Cl_2]_2·Et_3N和[η~6-C_6Me_6)Ru(μ-H_2)(μ-Cl)Ru(η~6-C_6Me_6)]Cl在温和条件下对芳香族化合物的均相催化加氢较为有效。但这些均相催化剂不太稳定,而且不容易从反应产物中分离出,也不易回收使用。为了克服这些缺点,这十年来,高分子金属催化剂的研究很活跃。聚酰胺-铂络合物和具有邻氨基苯甲酸基团的聚苯乙烯-铑络合物可作为苯加氢催化剂,但需要高温或高压的反应条件。我们曾制备了二氧化硅为载体的聚酰胺-铑络合物和二甲氨基或吗啉基取代的聚氯乙烯-铑络合物,并证明在常温常压下能够催     

用铑催化剂和金属助催化剂的甲醇羰基化反应过程

正羰基化反应生产醋酸的过程中使用金属助-催化剂,助催化剂作为铑的稳定剂和/或速度促进剂的有效性,金属对铑的摩尔比约为0.5~40。过程包括,在以铑为基础的催化剂金属络合物,     

钛催化的不对称硫醚氧化研究进展

手性亚砜是重要的手性中间体和辅剂、手性配体和催化剂、手性药物.手性亚砜可以采用生物方法和化学方法来合成,化学方法包括手性辅剂诱导、手性氧化剂氧化、手性拆分和不对称催化等.手性金属络合物催化硫醚的不对称氧化是合成手性亚砜最有效的方法.理性设计各种手性金属络合物催化剂应用于催化对映选择性氧化潜手性硫醚反应中,近年来引起了化学家们较大的关注.作者简要综述了钛络合物催化剂在不对称硫醚氧化反应制备手性亚砜中的应用.     

Study of complexes of poly(vinyl pyrrolidone) with copper and cobalt on solid state

A polymer–metal complex is a metal complex containing a polymer ligand, showing a remarkably specific structure in which central metal ions are surrounded by a colossal polymer chain. Based on this polymeric ligand, the polymer–metal complex has interesting and important characteristics, especially catalytic activities. This activity is different from that of the corresponding ordinary metal complex of low molecular weight. In this work we studied the synthesis and characterization, in the solid state, of different poly(vinyl pyrrolidone)–cobalt (PVP/Co) and –copper (PVP/Cu) complexes. We used differential thermal analysis and FTIR as the experimental techniques. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1512–1518, 2004     

Preparation of ultrafine metal particles/polyurethane composites

Summary A new type of coordination polyurethane was prepared by incorporating the transition metal ions into the pyridine containing thermoplastic polyurethane films. Then the metal ions dispersed in the polyurethane matrix were reduced by controlling the exposure of the metal sites to NaBH₄ under mild condition. The reduction of the polyurethane metal complex films resulted in the production of amorphous ultrafine metal powders. The size of these powders was controlled by the content of the metal ions and the polarity of the polymer matrix. A polar polymer backbone and lower metal ion concentration favored to achieve a smaller particle. It was also found that the polymer chains prohibited the excessive aggregation of the metal atoms and have protective effect on the final metal powders.     

Adsorbed metal ions as stabilizers for the thermal degradation of polyacrylamide

The thermal degradation of polyacrylamide has been studied in the presence of various metal ions using thermogravimetry. The thermal decomposition of the polymer in general occurs at higher temperatures in the presence of metal ions than with the pure polymer. Empirical measures of the stabilizing effect of the metal ions have been made by determining the temperatures of 12% and 50% decomposition, and the integral procedural decomposition temperature (IPDT). For main group metal ions, the stabilizing effect, as measured by the difference in ipdt between polymer-metal complex and copolymer, was inversely proportional to the radius of the metal ion, suggesting that the strength of the complex between the ion and polymer is important in determining stability. Transition metal ions, in contrast, showed no simple dependence of stabilizing effect on ionic radius, but showed, instead, a dependence upon the ligand field stabilization energy.     

New antimicrobial agents: The synthesis of Schiff base polymers containing transition metals and their characterization and applications

A new polymeric Schiff base containing formaldehyde and 2‐thiobarbituric acid moieties was synthesized by the condensation of a monomeric Schiff base derived from 2‐hydroxyacetophenone and hydrazine. Polymer–metal complexes were also synthesized by the reaction of the polymeric Schiff base with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) acetate. The polymeric Schiff base and its polymer–metal complexes were characterized with magnetic moment measurements, elemental analyses, and spectral techniques (infrared, ¹H‐NMR, and ultraviolet–visible). The thermal behaviors of these coordination polymers were studied by thermogravimetric analysis in a nitrogen atmosphere up to 800°C. The thermal data revealed that all of the polymer–metal complexes showed higher thermal stabilities than the polymeric Schiff base and also ascribed that the Cu(II) polymer–metal complex showed better heat resistant properties than the other polymer–metal complexes. The antimicrobial activity was screened with the agar well diffusion method against various selected microorganisms, and all of the polymer–metal complexes showed good antimicrobial activity. Among all of the complexes, the antimicrobial activity of the Cu(II) polymer–metal complex showed the highest zone of inhibition because of its higher stability constant and may be used in biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Metal complexing properties of water-soluble poly(N-maleyl glycine) studied by the liquid-phase polymer-based retention (LPR) technique

Summary The separation of various metal ions by the water-soluble N-maleyl glycine polymer in conjunction with membrane filtration was investigated. The method is based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low-molecular-weight species from the polymer complex formed. It is shown that poly(N-maleyl glycine) can bind several metal ions in aqueous solution at pH 3. At higher pH, the water-soluble polymer can be applied to the separation and preconcentration of many metal ions. In addition, the maximum capacity values of the homopolymer for copper(II) were investigated and compared in the presence of various metal ions at different pHs.     

Synthesis and characterization of highly porous poly(methacrylic‐co‐triethylene glycol dimethacrylate) by suspension polymerization

Porous poly(methacrylic‐co‐triethyleneglycol dimethacrylate) (MAA‐3G) was prepared by suspension polymerization using benzoyl peroxide as an initiator, poly(vinyl alcohol) as a protective colloid, and n‐hexane as a porogenic agent. The prepared polymer was base hydrolysed using hydroxyl amine and sodium methoxide into the corresponding polyhydroxamic acid (HYOX). The metal binding behavior of polyhydroxamic acid with various metal ions, the effect of pH on the metal ion capturing, and the selectivity of the resin towards the different metal ions were also examined by means of atomic absorption spectrophotometer. The thermal stability of the prepared base‐hydrolysed polymer and the metal polymer complex was examined by thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC). The prepared porous polymer methacrylic‐co‐triethyleneglycol dimethacrylate and its different modulated forms were characterized by means of FTIR specroscopy and scanning electron microscope. The hydroxamic acid content was also examined by elemental analysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 149–159, 1999     

Application of FTIR spectroscopy for structural characterization of ternary poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes

The FTIR spectroscopic technique was used in the study of ternary polymer–metal complexes containing two polyelectrolytes of opposite charge and metal ions. The structure of the ternary (PAA‐Fe³⁺‐PVP) complexes was examined by following the changes in their infrared spectra. It was found that the shapes of the absorption bands of the resultant compounds are influenced by the presence of Fe³⁺. According to this result it was suggested that two types of structure which differ in the composition are formed, one of which results from the coordination of Fe³⁺ with PAA‐PVP complex and the other is due to the formation of Fe³⁺ polycarboxylate. Comparison between the spectrum of PAA‐PVP complex and those of the compounds resulted from the reaction between the two opposite charged electrolytes, PAA and PVP and each of the divalent metal chlorides NiCl₂, CoCl₂, CuCl₂, and ZnCl₂) led to the conclusion that a reaction took place between the divalent transition metal chlorides and the extent of reaction depends on the nature of metal ions and PAA‐PVP complex. The FTIR spectra of the precipitate resulted from the mixtures of PAA‐PVP and Ni(NO₃)₂ or Sr(NO₃)₂ were investigated. It was noted that the addition of Ni(NO₃)₂ or Sr(NO₃)₂ to the mixture of the electrolytes of PAA and PVP provoked appreciable changes in the characteristic spectral features of the complex resulting from the interaction of the metal ions with the polymer–polymer complex. The FTIR spectra of the precipitate resulted from the reaction between CeCl₃, ErCl₃, and LaCl₃ were also investigated. It was concluded that a reaction took place between the rare earth metals and the PPC. This means that ternary polymer–metal–polymer complexes were formed. The extent of changes in the spectral features differs from metal to metal according to the nature of metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

铀酰-salophen印迹聚合物的合成与性能研究

以一种铀酰配合物为模板,制备了一种用于从水相选择性分离铀酰的新型印迹聚合物。用5-氯甲基水杨醛和3,4-二氨基苯甲酸合成四齿配体salophen,再合成铀酰与salophen的配合物铀酰-salophen。然后以甲基丙烯酸甲酯为功能单体,二甲基丙烯酸乙二醇酯为交联剂,铀酰-salophen为模板,合成铀酰的印迹聚合物。聚合物中的铀酰通过酸浸除去。用平衡吸附法研究了聚合物对铀酰的吸附性能和选择识别能力,且探讨了实验条件对印迹聚合物吸附性能的影响。结果表明,在竞争金属离子存在下,印迹聚合物对铀酰具有较高的吸附能力和选择识别能力,选择性系数大于200,且可以循环使用。     

Selective retention properties to silver(I) and mercury(II) ions of poly(4‐vinylpyridine) methyl iodide studied by the liquid‐phase polymer‐based retention technique

The retention of various metal ions by water‐soluble poly(4‐vinylpyridine) methyl iodide in conjunction with ultrafiltration membrane was investigated. The method is based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molecular weight species from the polymer metal ion complex formed. It is shown that the polychelatogen can bind silver(I) and mercury(II) ions in aqueous solution at pH 1. At higher pH, the water‐soluble polymer can be applied to the separation and preconcentration of silver metal ions. Therefore, this polychelatogen is highly selective to Hg(II) at pH 1 with respect to metal ions such as Cd(II) and Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2578–2582, 2001     

壳聚糖负载催化剂的研究进展

天然高分子壳聚糖是一天然碱性多糖,它对金属离子具有良好的螫合能力,其配合物可作为氢化、氧化偶合、开环聚合、烯类单体聚合、酯化、醚化等反应的催化剂和引发剂。主要对壳聚糖负载催化剂的研究进展进行了综述。