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1.
本综述以催化活性中心的原子种类为分类标准,着重于催化活性物种和催化反应机理的研究,系统地总结了自90年代以来苯及其芳烃化合物羟化合成在均相催化体系的研究进展.从研究趋势分析,人们从简单的无机盐均相催化体系过渡到合成仿生含氮配体的络合物作为催化剂的液-液两相催化体系,目前以铁、钒、铜和钯为催化活性中心的配合物液相催化体系的研究比较集中.从研究机理上来看,研究者运用多种研究手段和方法,提出了在各自研究体系中的*OH、高价金属氧配合物、金属氧或过氧或氢过氧化合物(或自由基)的羟化活性物种的自由基机理和配合物机理等.  相似文献   

2.
Schiff碱铜配合物模拟过氧化物酶的研究   总被引:9,自引:0,他引:9  
两种Schiff碱铜配合物首次作为过氧化物酶的模拟物用于催化过氧化氢氧化苯酚的反应;分析了配合物的特征光谱;研究了Schiff碱铜配合物的催化氧化机理,建立了催化氧化反应动力学数学模型;讨论了过氧化氢/催化剂摩尔比、体系温度、体系pH和胶束微环境对催化反应速率的影响.结果表明:这两种Schiff碱铜配合物在不同的反应条件下均表现出过氧化物酶催化的特征.  相似文献   

3.
钯催化下共轭烯烃的Heck芳基化是立体选择性形成碳碳键的重要方法,在有机合成中广为应用[1].均相钯催化剂因难以从反应体系中分离回收,其实际应用受到限制.聚合物负载过渡金属催化剂因综合了均相和复相催化过程的优势,已越来越引起人们的关注,聚苯乙烯负载的膦钯配合物能有效地催化共轭烯烃的芳基化[2,3].Zhang等报道了聚合物负载菲咯啉钯(0)配合物催化丙烯酰胺的芳基化[4],但该催化剂的制备过程过于复杂.作者曾报道过聚γ巯丙基硅氧烷钯(0)配合物的合成,并证实其是苯乙烯、丙烯酸Heck芳基化反…  相似文献   

4.
系统地总结了逆向相转移催化在有机合成中的应用,逆向相转移催化的作用在于逆向相转移催化剂能将底物分子从有机相转移至水相中发生反应,着重介绍了几种典型的逆向相转移催化剂如吡啶及其衍生物;杯芳烃;环糊精及其衍生物,水溶性过渡金属配合物在有机合成中的应用。  相似文献   

5.
水溶性铑膦配合物催化烯烃氢甲酰化反应研究进展   总被引:1,自引:0,他引:1  
 水/有机两相体系中水溶性铑膦配合物催化的烯烃氢甲酰化反应由于具有环境友好和催化剂容易分离等优点而受到广泛关注. 其中水溶性催化剂体系已经用于丙烯氢甲酰化反应制备丁醛的工业化生产. 然而, 长链烯烃在含有催化剂的水相中溶解性较差, 反应速率较慢. 综述了有关加速水/有机两相体系中长链烯烃氢甲酰化反应的方法和进展, 包括使用具有表面活性的膦配体, 以及在催化体系中添加环糊精和表面活性剂等促进剂. 另外, 还讨论了有关内烯烃氢甲酰化反应和提高直链醛选择性的方法.  相似文献   

6.
设计并合成了四种联吡啶配体上共价修饰不同取代基的三羰基铼配合物fac-Re(L)(CO)_3Cl:即取代基分别为甲基(Re-Me)、羧基(Re-Ac)、季铵盐(Re-Qa)以及咪唑盐(Re-Im)的铼配合物,化合物的结构均经过核磁氢谱、质谱以及红外光谱的确认,测定了四种配合物第一和第二还原电位.分别以该系列铼配合物为催化剂和光敏剂、三乙醇胺为电子牺牲体构建了均相可见光催化还原CO_2体系,配体上取代基对催化剂的催化效果有显著的影响,催化活性Re-QaRe-Ac≈Re-MeRe-Im.不同实验条件下四种催化剂的吸收光谱随时间变化研究表明,铼配合物的催化效果和其在催化过程中的失活速率密切相关,其变化趋势与催化剂失活速率一致,催化剂的失活发生在催化剂得到一个电子后的单电子还原态中间体(One-electron reduced species,OER).瞬态吸收光谱检测到了催化过程中的OER的生成,证实光催化还原CO_2过程通过生成OER中间体进行的.  相似文献   

7.
陈良凤  王卓  康鹏 《催化学报》2018,39(3):413-420
光驱动二氧化碳还原实现可再生能源转化近年来引起普遍关注.利用小分子金属配合物电催化剂和吸光半导体材料构建的光电催化体系兼具电催化剂的高选择性和光电极的高光电转化效率等优点,在能源催化领域的应用日益广泛.已有将贵金属配合物催化剂用于光电催化二氧化碳还原的研究报道,但催化剂成本较高且制备方法不简便,在规模化实际应用中受到局限.基于早期的研究报道,我们发现非贵金属多联吡啶铁钴镍配合物在乙腈电解质中能高选择性电催化还原二氧化碳.结合半导体材料的特异性电荷分离性能从而将光能高效转化为电能驱动催化反应进行,我们选择廉价且易于制备的多联吡啶钴配合物催化剂,利用半导体硅晶片光电极,实现了均相体系二氧化碳的高效光电催化还原.我们采用电化学循环伏安法和恒电位电解法分别研究了催化剂在干燥和加水电解质环境中的催化还原行为,并且进一步研究了微量质子源的加入对半导体界面催化过程的影响,从而提出一种能改善半导体光电催化体系选择性的新方法.首先我们构建了电化学三电极体系,研究了在暗环境下三联吡啶钴和二联吡啶钴这两种配合物催化还原二氧化碳的电流密度和电解产物分布情况.由循环伏安曲线发现,这两种配合物都有两组催化还原峰,第二个基于吡啶配体还原的峰具有明显的催化特性.少量水的加入能进一步增加催化电流强度,而三联吡啶钴配合物的催化增强效果更加显著.在变扫速条件下将电流密度对扫速平方根进行归一化处理,发现无论在干燥环境还是少量加水环境下,两种催化剂的归一化电流密度均随扫速降低而明显增强,证明了催化剂具有电催化特性.推测水的催化增强作用可能与质子化电催化过程活性中间体有关.恒电位电解结果说明电催化产物以一氧化碳为主.基于上述研究,我们构建了光电化学三电极体系,以单晶硅片为工作电极,研究了在光照环境下这两种配合物催化还原二氧化碳的电流密度和电解产物分布情况.研究发现,催化剂对二氧化碳仍具有催化活性,光电压为400 m V.不同于硅线电极加水导致产氢,改用少量甲醇做质子源后,光电流强度进一步增强,竞争性产氢受到了抑制,从而使一氧化碳的法拉第效率得到显著提高,分别优化为94%和83%,并且光电流在14h内保持稳定.推测甲醇质子源的催化增强作用可能是与改变光电极液接界面传质动力学过程有关.  相似文献   

8.
合成了手性吡啶醇二氧合钼(VI)及二氧合钨(VI)配合物,采用这两种配合物作为催化剂,实现了在水中对顺丙烯膦酸(CPPA)的催化不对称环氧化.这两种催化剂不溶于水,因此,这是一个发生在固液两相界面上的异相催化不对称环氧化反应.其中手性吡啶醇二氧合钼在0℃下的对映选择性ee值达到71%;加入相转移催化剂四正丁基溴化铵,催化剂的活性和对映选择性有显著提高,其中手性吡啶醇二氧合钨在50℃下ee值由54%提高到78%.手性吡啶醇二氧合钼和二氧合钨催化剂可以回收再使用.  相似文献   

9.
金属卟啉催化烯烃环氧化及反应机理研究   总被引:5,自引:0,他引:5  
李臻  夏春谷 《化学进展》2002,14(5):384-390
本文就铁卟啉及锰卟啉模拟酶体系近年来在催化烯烃环氧化反应机理方面的最新研究成果进行了详细阐述。均相催化剂固载化技术的应用,使金属卟啉配合物担载于无机载体上克服了卟啉的二聚、催化剂再生等难题,有力地推动了金属卟啉配合物应用研究的发展。  相似文献   

10.
近年来,铁、钴、镍和锰配合物催化体系在廉价金属催化领域取得了系列进展.由于其独特的性质和出色的催化性能,钴配合物在均相催化反应中最引人注目,所涉及的(脱氢)氢化反应在学术研究和化工行业中起着重要作用.本文根据氢化、转移氢化、无受体脱氢、脱氢偶联、借氢等反应类型总结了均相钴催化氢化、脱氢反应的研究进展,并概述了钴催化剂的反应性能、催化应用以及反应机理.  相似文献   

11.
A novel and practical catalytic method for efficient and highly selective oxidation of a wide range of benzylic, allylic, aliphatic, primary, and secondary alcohols to the corresponding aldehydes and ketones using tetrabutylammonium peroxomonosulfate catalyzed by tetradentate Schiff base–MnIII complexes has been developed. Electron‐deficient and hindered alcohols required longer reaction times for oxidation in this catalytic system. The electron‐poor and hindered salicylidene ring of the ligand enhanced the catalytic activity and stability of Mn catalysts. The desired turnover numbers obtained in the oxidation reactions indicated the high efficiency and relative stability of these simple Schiff base complexes in this catalytic system.  相似文献   

12.
In the present study we have analyzed the nature of palladium complexes in the catalytic system for selective carbon-sulfur bond formation via the addition of S-S and S-H bonds to alkynes. For the first time the mononuclear and dinuclear palladium complexes were clearly detected by DOSY NMR under the catalytic conditions. It was demonstrated that the concentration of these palladium complexes strongly depends on the amount of phosphine ligand available under reaction conditions.  相似文献   

13.
The two Schiff base cobalt(II) complexes, CoL1 and CoL2, were synthesized and characterized. The metallomicelle made up of the cobalt(II) complexes and surfactants (CTAB, LSS and Brij35), as mimic peroxidase metalloenzyme, were used in the catalytic oxidation of phenol by H2O2. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were studied. The acid effect of reaction system, structural effect of the complexes, and effect of temperature on the rate of the phenol oxidation catalyzed by the mimetic peroxidases have been discussed. The results showed that the schiff base cobalt(II) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.  相似文献   

14.
New Pd(II), Pt(II) and Rh(I) N-heterocyclic carbene (NHC) complexes containing two NHC units linked by an ortho-xylyl group are described and structurally and spectroscopically characterised. The Pt(II) complexes represent the first examples of Pt-bis(NHC) complexes where the NHC units are linked by an ortho-xylyl group. Functionalisation of the bis(NHC) ligands with heptyl groups has been used as a means of enhancing the solubility of the complexes, in order to facilitate spectroscopic characterisation and catalytic studies. The catalytic activity of the palladium(II) complexes in Heck and Suzuki cross-coupling reactions has been examined to investigate any effects of the diverse structural changes, though these appear to be insignificant.  相似文献   

15.
Three novel cobalt(II) complexes of the benzoaza-15-crown-5 Schiff base, CoL1, CoL2, and CoL3 were synthesized and characterized. Metallomicelles made from CoL and surfactants (CTAB, LSS, and Brij35) were used as mimetic peroxidase in the catalytic oxidation of phenol by H2O2. For comparison, the catalytic activity of the complexes (CoL1, CoL2, and CoL3) were also investigated. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were studied. The acid effect of reaction system, structural effect of the complexes, and effect of temperature on the rate of the phenol catalytic oxidation by the mimetic peroxidase were discussed. The results show that the Schiff base cobalt(II) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.  相似文献   

16.
The thermal stability of metal complexes immobilized on the surface of silica and its connection with the catalytic activity in the oxidation of hydrogen were investigated. High catalytic activity was exhibited by heterogenized platinum and palladium acetylacetonate near room temperatures in the initial state and by γ-aminopropylsilicas treated with platinum and palladium complexes. The catalytic activity of the metal complexes correlates with their thermal stability and with the ability to undergo oxidation to a metal state with high valence. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
自1938年Otto Roelen从事Fisher-Ttopsch发现氢甲酰化反应以来,这类反应一直是有机合成和金属催化领域热点之一。目前合成醛及其衍生物的氢甲酰化反应已成为金属均相催化体系中使用可溶性催化剂最大的工业应用范例。而自20世纪90年代出现的Cativa(铱基催化剂),因具有原料价格低,稳定性好,易溶解,  相似文献   

18.
It has been reported that three aza crowned Schiff base cobalt (II) complexes were synthesized and characterized, and the metallomicelle made up of the cobalt (II) complexes and surfactants(Brij35, CTAB, LSS), as mimic hydrolytic metalloenzyme, was used in catalytic hydrolysis of bis(4‐nitrophenyl) phosphate (BNPP). The analysis of specific absorption spectrums of the hydrolytic reaction systems indicated that key intermediates made up of BNPP and Co (II) complexes are formed in the reaction process of BNPP catalytic hydrolysis. The mechanism of BNPP catalytic hydrolysis proposed is based on the analytic result of specific absorption spectra. Based on the mechanism proposed, a kinetic mathematical model for the calculation of the kinetic parameter of BNPP catalytic hydrolysis has been established. The acid effect of reaction system, structure effect of the complexes, effect of temperature and effect of micelles on the rate of BNPP hydrolysis catalyzed by the complexes have been discussed.  相似文献   

19.
Metallomicelles made from two Schiff base manganese(III) complexes (MnL1 and MnL2) and surfactants (CTAB and Brij35) were used as mimetic peroxidase in the catalytic oxidation of phenol by H2O2. The catalytic activity of the complexes (MnL1 and MnL2) were investigated. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were also studied. The results show the optimum acidity of the enzyme-like system in the paper is ca. pH 7.0, the optimum temperature which is ca. 35°C and the optimum molar ratio of H2O2 to the complex is ca. 30 in the complexes-H2O2-buffered solution; the Schiff base manganese(III) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.  相似文献   

20.
Mono- and dinuclear N-heterocyclic carbene palladium complexes with diazine ligands were synthesized and characterized through adjusting the stoichiometric ratio of the reactants. The catalytic properties of all complexes were further studied in the Mizoroki–Heck reaction. The results indicated that the dinuclear complexes induced some benefits in catalytic behavior.  相似文献   

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