高分子钯络合物催化的亚胺化合物的加氢反应

制备了一系列以二氧化硅为载体的侧链上含有各种氮配位基团的聚硅氧烷-钯络合物,这些高分子钯络合物能够在常温常压下催化亚胺化合物的加氢反应并表现出不同程度的催化活性.对其中聚-(N,N-二乙酰基)-γ-氨丙基硅氧烷-钯络合物催化的亚苄基苯胺的加氢反应做了比较深入的研究,发现该催化剂在反应中是稳定的并给出唯一的加氢产物,络合物中的N/Pd原子比、反应温度以及不同底物对反应速度的影响也被报道.     

膨胀石墨负载钯纳米颗粒催化六价铬还原反应

采用高分子辅助的浸渍还原法,制备得到膨胀石墨(EG)负载的纳米钯催化剂(Pd-EG),采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等手段对催化剂组成、结构、形貌和价态进行了表征,并考察了Pd-EG催化剂在六价铬还原反应中的活性.结果表明,催化剂中纳米钯颗粒均匀分散在膨胀石墨上,平均粒径为4.37 nm,金属负载量质量分数为0.446%.该催化剂对六价铬还原反应具有良好的催化性能,可将六价铬完全转化为三价铬,在pH=4.0及45℃条件下反应转化频率(TOF)达到3186 h-1;催化剂经过多次重复使用后的活性仍保持稳定.     

纳米多孔金催化有机反应研究进展

综述了金纳米多孔材料在催化CO和醇的氧化反应、含不饱和键化合物(炔烃、亚胺和α,β-不饱和醛)的加氢还原反应、炔基芳香醛与炔烃的成环反应、氧化脱氢偶联构筑新C—C键反应和C—X(X=B,Si)键形成反应中的应用研究结果.     

含有酯基二茂铁亚胺环钯化合物催化Suzuki和Heck反应

合成并表征了系列含有酯基二茂铁亚胺环钯化合物.结果表明,该系列环钯催化剂在纯水或有机溶剂中均能高效催化Heck和Suzuki偶联反应.     

壳聚糖亚胺环钯化合物的合成及其催化性能研究

壳聚糖与苯甲醛或其衍生物作用制得壳聚糖席夫碱, 再与氯化钯锂的甲醇溶液作用, 制得壳聚糖亚胺环钯催化剂. 该类催化剂对空气和水稳定, 对于苯乙烯与芳基碘的交叉偶联反应具有较高的催化活性和选择性, 经简单分离回收可重复使用多次. 为立体选择性合成各种取代的1,2-二苯乙烯提供了一种制备简单、实用的高活性绿色催化剂体系.     

水溶性亚胺配体/钯催化的室温 Suzuki 反应

 设计并合成了一种新型水溶性亚胺双齿配体 I, 并得到其单晶结构. 该配体具有半配位效应和绿色化学特征, 与氯化钯组成的催化体系在空气和室温条件下, 可有效催化乙醇水溶液中的溴代芳烃与芳基硼酸的 Suzuki 交叉偶联反应. 在 n(ArBr) = 0.5 mmol, n(ArB(OH)₂) = 0.75 mmol, x(PdCl₂) = 1%, x(I) = 2%, n(K₂CO₃) = 1.0 mmol, c(EtOH) = 50% 水溶液的优化条件下, 经 20 min 反应, 分离收率即可达到 99%.     

壳聚糖亚胺环钯化合物对碘代苯与丙烯酸反应的催化性能

以苯甲醛或其衍生物对壳聚糖进行接枝改性制得了壳聚糖席夫碱配体,再与Li2PdCl4进行环钯化合成了壳聚糖亚胺环钯化合物催化剂1-10.研究了该类催化剂对碘代苯或碘苯衍生物与丙烯酸偶联反应的催化性能,结果表明该类催化剂具有较好的催化活性和一定的重复使用性能.     

钯纳米粒子在电极表面的制备及其对氧的催化还原

纳米微粒的体积效应使其成为表面纳米工程及功能化纳米结构材料制备的理想研究对象 [1～ 3] .纳米粒子具有独特的电子、催化及光学特性[4 ] ,近年来关于纳米粒子的制备及其在材料科学领域中的应用受到研究者的极大关注 .而贵金属纳米粒子由于其在催化领域中的广泛应用而成为最重要的研究对象之一[5,6 ] .电催化氧还原是一直为化学家瞩目的研究领域[7～ 9] .研究主要目的之一是寻找合适的氧电极反应催化剂 ,并使之能够应用于燃料电池中 .其中催化氧电极材料研究得最多的是贵金属 Pt[10 ,11] .贵金属 Pd对氧催化还原的研究工作很少 .我们首次…     

纳米多孔金属电催化剂在氧还原反应中的应用

燃料电池是将化学能直接转化为电能的能量转换装置,具有绿色、高效、便携等特点。对于大多数使用氧气或者空气为氧化剂的燃料电池而言,其阴极氧还原反应动力学缓慢、稳定性差是阻碍该技术走向商业化的主要因素,因此开发高催化活性和良好稳定性的低成本氧还原催化剂非常重要。基于脱合金法制得的纳米多孔金属是一类新型的宏观尺度纳米结构材料,其独特的开放型孔道结构、优良的导电性和结构的可调控性使其在电催化相关领域具有广泛的应用。本文侧重于讨论纳米多孔金属作为氧还原催化剂时所展示的一系列结构特性,及其在发展新一代高性能一体化燃料电池催化剂中所展示的机会。     

钯催化合成新型聚合物聚亚胺酮

以二溴化芳香酮和芳香二胺为单体,通过钯催化的胺化缩聚反应合成了新型聚合物——聚亚胺酮,其结构经1HNMR,IR和元素分析确认。     

A computational investigation of the hydrogenation of imines catalyzed by rhodium thiolate complexes

The mechanism of imine hydrogenation catalyzed by thiolate complexes of Rh(III) bearing a hydrotris(3,5‐dimethylpyrazolyl)borato ligand has been investigated via the density functional theory calculations. The overall catalytic cycle for heterolytic cleavage of H₂ and hydrogenation of N‐benzylidenemethylamine by the model catalyst [TpRh(bdt)MeCN)] is presented in detail. The results show that the reaction proceeds via an ionic mechanism through three steps: formation of dihydrogen complex, protonation of imine and the hydride transfer process. Protonation of imine occurs after the formation of Rh(H)‐S(H) moiety. For the whole catalytic cycle, the heterolytic splitting of dihydrogen is the step with the highest free energy barrier. © 2014 Wiley Periodicals, Inc.     

Asymmetric aza-Henry reaction of fluoromethylated imines catalyzed by cinchona-derived bifunctional thiourea

The asymmetric aza-Henry reaction of fluoromethyl imines derived from 4-methoxyaniline with nitromethane was achieved under mild conditions using cinchona-derived bifunctional thiourea as catalyst. A series of chiral fluoromethylated β-nitroamines were synthesized and their transformation to optically pure 4-fluoromethyl-2-imidazolidones was illustrated.     

Palladium(II) acetate‐catalyzed reduction of imines to the corresponding amines by triethylsilane

Reduction of a variety of imine compounds with triethylsilane in the presence of catalytic amounts of palladium(II) acetate in ethanol resulted in the formation of the corresponding amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.     

Asymmetric hydrogenation of imines and olefins using phosphine-oxazoline iridium complexes as catalysts

Herein we describe the synthesis of a new class of chiral phosphine-oxazolines and their application as ligands in iridium-catalyzed hydrogenations. Mechanistic aspects of olefin hydrogenation with this class of iridium catalysts are discussed and a selectivity model to help rationalize the results obtained is also presented.     

Simple manganese carbonyl catalyzed hydrogenation of quinolines and imines

Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese. Herein, we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls, Mn₂(CO)₁₀ or MnBr(CO)₅, thus eliminating the prerequisite pincer-type or bidentate ligands.     

Selective hydrogenation of chloronitrobenzenes catalyzed by palladium complex of silica-supported chitosan

A palladium complex of silica-supported chitosan has been found to catalyze the hydrogenation of p-, m- and o-chloronitrobenzene, and of 4-chloro-1,3-dinitrobenzene to p-, m- and o-chloroaniline, and 4-chloro-3-aminoaniline in 100% yield, respectively, at room temperature and under atmospheric pressure, and the side reaction, dechlorination, has not been observed. This catalyst was very stable, the turnover numbers (p-chloronitrobenzene to p-chloroaniline cycles / palladium atom) reached 9000 in 17 hours.     

Synthesis of amides from imines using Et3SiH/Zn system

A simple and efficient approach for the synthesis of amides by the reaction of imines and acyl chlorides in the presence of Et₃SiH/Zn system in THF at ambient temperature is reported. Mild reaction conditions, good yields of products, short reaction time and operational simplicity are the advantages of this procedure. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification of new catalysts for the asymmetric reduction of imines into chiral amines with polymethylhydrosiloxane using high-throughput screening

The use of high-throughput techniques allowed the rapid identification of new catalysts for the enantioselective reduction of imines using polymethylhydrosiloxane (PMHS) as a reducing agent. By a simple modification of the chiral ligand structure that came out of the screening, the enantioselectivity of the reduction was increased from 40% ee to 60% ee.     

Transfer hydrogenation of ketones catalyzed by ruthenium complexes

Oxidation of 1,3,5- and 1,2,4-trimethylbenzenes using heteropoly vanadomolybdate as catalyst in the presence of hydrogen peroxide under homogeneous conditions has been investigated. Phenol formation in the case of 1,2,4-trimethylbenzene and only side chain oxidation in the case 1,3,5-trimethylbenzene were observed. This behavior is explained in terms of the charge densities on different centers of both substrate molecules calculated by the MNDO method.