六齿配位的8-羟基喹啉铁催化过氧化氢氧化环己烷的研究

合成了几种具六齿配位的8-羟基喹啉铁类配合物,考察了这些配合物在催化过氧化氢氧化环己烷的催化性能。结果表明,配体的卤素取代基对催化剂有稳定作用,能提高其催化活性。二卤代的催化剂具有稳定的六齿配位结构,其催化反应速率慢;采用混合配体配位的催化剂能够明显加快反应速率,提高催化活性。     

蒙脱土担载钴配合物催化剂制备及性能研究

制备了系列蒙脱土担载钴(Ⅱ)(Co(Ⅱ))配合物催化剂,并对其结构进行了X射线衍射和透射电镜等表征,初步研究了蒙脱土担载钴(Ⅱ)配合物催化剂对烯烃的催化氧化性能.结果表明:配体进入了蒙脱土的片层间与Co(Ⅱ)配位,形成蒙脱土担载的铜配合物复合催化材料;在催化剂催化H2O2氧化苯乙烯的反应中,对苯甲醛和环氧苯乙烷的选择性高达94.7%,转化率达到38.4%;在环己烯的氧化反应中,对环氧环己烷、环己醇、环己烯醇和环己烯酮的选择性共达到98.5%,转化率达到33.2%.     

不对称双席夫碱Ni配合物催化环己烯环氧化

本文以3,5-二叔丁基水杨醛与邻苯二胺合成席夫碱配体(L2),用该配体与Ni2+配位合成中间体(L2-Ni),再与不同的芳香醛反应制得一系列不对称Salen-Ni(Ⅱ)配合物。利用傅里叶变换红外光谱和元素分析对配体和配合物进行了表征。然后以30%的过氧化氢为氧源,以一系列不对称Salen-Ni(Ⅱ)配合物为催化剂,探究了环己烯环氧化反应的催化性能和配体上不同推拉电子基团对催化反应的影响。通过优化反应条件,环己烯的转化率和选择性最高可达到67.4%、43.5%。     

PS负载乙二胺系列钼配合物催化环己烯环氧化的反应性能

以大孔聚苯乙烯树脂为载体,乙二胺(en)、二乙烯三胺(dien)及三乙烯四胺(trien)为配体,合成了PS-en-Mo(Ⅵ)、PS-dien-Mo(Ⅵ)以及PS-trien-Mo(Ⅵ)催化剂,并对其进行了结构表征,IR谱证实已在PS载体完成对目的物的负载;XPS谱的结果表明,所合成的以上3种Mo配合物中的钼皆以Mo(Ⅵ)价态形式存在,据此提出了所合成高分子金属配合物的可能结构。PS负载乙二胺系列钼配合物在催化t-BuOOH环氧化环己烯反应中,都具有很高催化活性,但随着配体分子中N原子个数的增加,催化选择性降低明显。认为这是N原子配位能力强,供电能力高,与Mo配位后形成的Mo—N键,大大减低了Mo的正电性,使Mo的Lewis酸性降低,从而使Mo(Ⅵ)活性中心与t-BuOOH形成金属双氧活性中间体的能力下降所致。配体分子N原子的增加,碱性增强,不仅进一步减低Mo的Lewis酸性,且会使t-BuOOH分解,最终导致选择性降低严重。     

螯合型羰基铑配合物催化甲醇羰基化反应的机理研究

报道了螯合型正方平面羰基铑配合物催化甲醇羰基化反应的机理研究。通过含有两种与铑具有不同配位能力的授体的配体,与四羰基二氯二铑形成螯合型正方平面阳离子配合物。研究证明,该类配合物在催化甲醇羰基化反应过程中,其活性物种区别于文献报道的[Rh(CO)2I2]-阴离子。配合物中铑与吡啶环上共轭N形成的N→Rh配键,在羰基化反应过程中并非通常认为的断裂而是形成新的活性物种,即配体与铑作为整体参与了CH3I的氧化加成及CH3COI的生成过程。通过对相应的聚合物配体铑催化剂的研究,进一步证实了这个反应机理。这一结果,对该类催化剂分子设计,以及克服其工业使用中的催化剂沉淀失活等现象均有重要意义。     

分子氧氧化环己烯负载型催化剂的制备与选择

在乙醇溶剂中,合成出三种希夫碱配体和四种不同金属离子希夫碱配合物,并用红外线对其结构进行表征,表明合成出希夫碱配体及其配合物.接着以分子氧为氧源,金属希夫碱配合物为催化剂,考察其对环己烯的催化氧化性能,从而筛选出较佳的配位体:水杨醛缩乙二胺配位体和较佳的金属离子钴离子;进而以水杨醛缩乙二胺钴配合物为均相催化剂,采用两种方法将其负载在硅藻土、活性炭、分子筛和石英砂上,并考察该非均相催化剂催化活化分子氧氧化环己烯的催化氧化性能,结果表明,硅藻土为较佳无机载体,固载时,柔性配体法优于浸渍法.     

染料木黄酮钙配合物的合成、表征及清除自由基和抑菌活性

以染料木黄酮和氢氧化钙为原料合成了染料木黄酮钙配合物,并采用红外光谱、紫外光谱、热重分析及核磁共振等手段对其结构进行了表征。采用邻苯三酚自氧化法、Fenton反应-邻二氮菲光度法和DPPH自由基方法分别测定配体与配合物清除超氧自由基、羟基自由基和DPPH自由基的能力,并且考察了它们的抑菌性质,测定了其抑制大肠杆菌、绿脓杆菌、李斯特氏菌的能力。结果表明:染料木黄酮以分子中的4位羰基O和5位羟基O与Ca2+配位而形成分子式为[Ca(C15H9O5)2].2H2O的配合物。在相同浓度下,配合物清除超氧自由基和羟自由基的能力明显强于配体,而清除DPPH自由基的能力仅略有增强。配体及其配合物对大肠杆菌、李斯特氏菌、绿脓杆菌都有一定的抑菌效果,配合物的抑菌性仅略高于配体。     

铁-卟啉氧化还原酶体系结构与氧化还原机理分析

铁-卟啉体系是生物体内众多重要氧化还原酶的活性中心。卟啉体系属于一种大环共轭配体结构,其与铁原子结合即可形成铁-卟啉体系,由于卟啉体系与铁原子配位情况较小,使得其分子配合物较为复杂。通过对该体系氧化还原反应机理的深入研究得知在整个反应过程中会出现许多带有正电荷或者自由基的铁氧复合物中间体,这些中间体的空间构造很复杂,传统的价键理论等很难作出合理的解释。基于此,开展对铁-卟啉氧化还原酶体系机构与氧化还原机理的研究,以为生物有机化学等学科的教学与科研提供一定的借鉴。     

铁配合物催化的有机反应研究进展

铁配合物在有机反应中起催化作用,很多化学反应需要有催化剂,这是化学反应的基本条件,铁配合物就是一种催化剂。主要从铁配合物的类型和基本定义、铁配合物催化剂的主要反应类型概述铁配合物催化的有机反应研究进展,希望为研究铁配合物的专家与学者提供参考。     

缩二脲锌配合物的合成与表征

以硝酸锌、乙酸锌及硫酸锌和缩二脲为原料,在甲醇溶液中反应合成了3种含有不同阴离子和结晶水的缩二脲锌配合物[Zn(bi)2](NO3)2·2H2O、[Zn(bi)2](Ac)2·1.5H2O和[Zn(bi)2]SO4·0.25H2O(bi=NH2CONHCONH2),用EDTA配位滴定、元素分析、X射线粉末衍射、红外光谱对产物进行组成和结构表征,并研究了配合物的热分解过程。实验结果表明,锌离子与缩二脲中的羰基氧原子配位,形成了配位数为4的配合物。配合物的热分解过程包括失水、配体及阴离子的氧化分解过程,最后完全分解形成氧化锌。     

Electronic structure and reactivity of three-coordinate iron complexes

[Reaction: see text]. The identity and oxidation state of the metal in a coordination compound are typically thought to be the most important determinants of its reactivity. However, the coordination number (the number of bonds to the metal) can be equally influential. This Account describes iron complexes with a coordination number of only three, which differ greatly from iron complexes with octahedral (six-coordinate) geometries with respect to their magnetism, electronic structure, preference for ligands, and reactivity. Three-coordinate complexes with a trigonal-planar geometry are accessible using bulky, anionic, bidentate ligands (beta-diketiminates) that steer a monodentate ligand into the plane of their two nitrogen donors. This strategy has led to a variety of three-coordinate iron complexes in which iron is in the +1, +2, and +3 oxidation states. Systematic studies on the electronic structures of these complexes have been useful in interpreting their properties. The iron ions are generally high spin, with singly occupied orbitals available for pi interactions with ligands. Trends in sigma-bonding show that iron(II) complexes favor electronegative ligands (O, N donors) over electropositive ligands (hydride). The combination of electrostatic sigma-bonding and the availability of pi-interactions stabilizes iron(II) fluoride and oxo complexes. The same factors destabilize iron(II) hydride complexes, which are reactive enough to add the hydrogen atom to unsaturated organic molecules and to take part in radical reactions. Iron(I) complexes use strong pi-backbonding to transfer charge from iron into coordinated alkynes and N 2, whereas iron(III) accepts charge from a pi-donating imido ligand. Though the imidoiron(III) complex is stabilized by pi-bonding in the trigonal-planar geometry, addition of pyridine as a fourth donor weakens the pi-bonding, which enables abstraction of H atoms from hydrocarbons. The unusual bonding and reactivity patterns of three-coordinate iron compounds may lead to new catalysts for oxidation and reduction reactions and may be used by nature in transient intermediates of nitrogenase enzymes.     

N-羟基邻苯二甲酰亚胺与负载型铁氧化物催化氧化环己烷研究

考察了N-羟基邻苯二甲酰亚胺与负载型铁氧化物相组合时催化氧化环己烷的效果以及可能存在的机理。用浸渍法制备了多种负载型铁氧化物催化剂,研究了用不同载体和不同铁来源制备的催化剂与N-羟基邻苯二甲酰亚胺共同催化氧化环己烷,比普通的三价铁盐与N-羟基邻苯二甲酰亚胺相组合催化氧化环己烷好。N-羟基邻苯二甲酰亚胺与Fe/ZrO₂在 100 ℃和氧压0.6 MPa下反应6 h,环己烷转化率可达53%。通过穆斯堡尔谱图等实验手段提供的信息提出可能的催化机理, 负载型铁氧化物晶体缺陷产生的Fe⁴⁺是激发N-羟基邻苯二甲酰亚胺为PINO自由基的来源。     

金属-有机笼状化合物在限域催化领域的研究进展

金属-有机笼状化合物（MOCs）是一种由金属离子与有机配体通过配位自组装而成的具有特定空腔的化合物。MOCs的可变价金属离子、功能性配体和形状各异的空腔结构为催化活性位点提供了多种可能，MOCs的限域催化作用实现了对不同类型反应的效率提升，因此，本文从金属离子、功能性配体以及其限域空腔三方面来详细阐述金属-有机笼状化合物在催化领域的研究进展，其中，金属-有机笼状化合物的金属离子催化性能主要表现在光致产氢、光致产氧和二氧化碳还原，其功能性配体能够调节不对称催化反应的对映选择能力，其限域空腔为光二聚体的形成起到了很好的催化效果并且也能够对一般的有机反应起到明显的促进效果。     

Efficient aerobic oxidation of hydrocarbons with O2 catalyzed by DDQ/NHPI

BACKGROUND: Organocatalysis, a promising strategy for the oxidation of organic compounds, does not involve the use of a catalytic metal. In this work, an efficient organocatalyst system consisting of 2,3‐dichloro‐5,6‐dicyano‐benzoquinone (DDQ) and N‐hydroxyphthalimide (NHPI) was studied. RESULTS: 72.2% conversion with 92.3% selectivity for acetophenone was obtained in ethylbenzene oxygenation catalyzed by DDQ/NHPI under 0.3 MPa of molecular oxygen at 80 °C for 10 h. In addition, other hydrocarbons were also oxidized with high efficiency using this catalyst system. UV/Vis spectroscopy of the catalytic system indicated that DDQ accelerated the generation of free radical phthalimido‐N‐oxyl (PINO) by abstracting a hydrogen atom from NHPI. CONCLUSION: An efficient organocatalyst system consisting of DDQ and NHPI for selective oxidation of hydrocarbons to corresponding ketones with molecular oxygen as oxidant is reported. DDQ promoted the generation of PINO from NHPI, and the oxidation reaction was accelerated via PINO. This organocatalyst system should be useful for the design of highly selective catalysts for hydrocarbon oxidation. Copyright © 2010 Society of Chemical Industry     

Fe-TAML催化H_2O_2降解甲基橙的实验研究

选用三价铁盐与草酸二乙酯、对硝基苯酚、多聚磷酸、四氢呋喃合成铁四胺基大环配位体Fe-TAML。以甲基橙溶液模拟染料废水,考察了各因素对甲基橙降解性能的影响。结果表明,在温度为25℃,pH为9,H_2O_2浓度为0.785 mol/L,催化剂Fe-TAML投加质量浓度为4 mg/L的条件下,甲基橙脱色率可达93.86%。同时机理研究表明,催化反应过程中,产生了羟基自由基和高价铁两种活性氧化物种,二者共同作用于甲基橙的降解。     

Experimental and theoretical study on N-hydroxyphthalimide and its derivatives catalyzed aerobic oxidation of cyclohexylbenzene

The liquid phase oxidation of cyclohexylbenzene (CHB) is a new green synthetic approach to cyclohexylbenzene-1-hydroperoxide (CHBHP), a key intermediate for preparing phenol and cyclohexanone. In this work, aryl-substituted (Cl and Br) derivatives of N-hydroxyphthalimide (NHPI) were synthesized and their catalytic performances for CHB oxidation were studied. In addition, geometric optimization and transition state search were performed using DFT calculations. Both experimental and theoretical studies have proven that chloro-substitution on NHPI can significantly improve its catalytic effects on the oxidation of CHB by oxygen. Compared with NHPI, CHB conversion and selectivity of CHBHP over Cl₄NHPI were increased by 10.47% and 13.24%. The strategy of aryl -substituting NHPI with halogen atoms proposed in this study would provide a potential way to the development of new NHPI-based catalysts for aerobic oxidation reactions.     

Innovation of Hydrocarbon Oxidation with Molecular Oxygen and Related Reactions

An innovation of the aerobic oxidation of hydrocarbons through catalytic carbon radical generation under mild conditions was achieved by using N‐hydroxyphthalimide (NHPI) as a key compound. Alkanes were successfully oxidized with O₂ or air to valuable oxygen‐containing compounds such as alcohols, ketones, and dicarboxylic acids by the combined catalytic system of NHPI and a transition metal such as Co or Mn. The NHPI‐catalyzed oxidation of alkylbenzenes with dioxygen could be performed even under normal temperature and pressure of dioxygen. Xylenes and methylpyridines were also converted into phthalic acids and pyridinecarboxylic acids, respectively, in good yields. The present oxidation method was extended to the selective transformations of alcohols to carbonyl compounds and of alkynes to ynones. The epoxidation of alkenes using hydroperoxides or H₂O₂ generated in situ from hydrocarbons or alcohols and O ₂ under the influence of the NHPI was demonstrated and seems to be a useful strategy for industrial applications. The NHPI method is applicable to a wide variety of organic syntheses via carbon radical intermediates. The catalytic carboxylation of alkanes was accomplished by the use of CO and O₂ in the presence of NHPI. In addition, the reactions of alkanes with NO₂ and SO₂ catalyzed by NHPI provided efficient methods for the synthesis of nitroalkanes and sulfonic acids, respectively. A catalytic carbon‐carbon bond forming reaction was achieved by allowing carbon radicals generated in situ from alkanes or alcohols to react with alkenes under mild conditions. 1 Introduction 2 Discovery of NHPI as Carbon Radical Producing Catalyst from Alkanes 2.1 Historical Background 2.2 Catalysis of NHPI in Aerobic Oxidation 3 NHPI‐Catalyzed Aerobic Oxidation 3.1 Oxidation of Benzylic Compounds 3.2 Alkane Oxidations with Molecular Oxygen 3.3 Oxidation of Alkylbenzenes 3.4 Practical Oxidation of Methylpyridines 3.5 Preparation of Acetylenic Ketones via Alkyne Oxidation 3.6 Oxidation of Alcohols 3.7 Selective Oxidation of Sulfides to Sulfoxides 3.8 Production of Hydrogen Peroxide by Aerobic Oxidation of Alcohols 3.9 Epoxidation of Alkenes using Molecular Oxygen as Terminal Oxidant 4 Carboxylation of Alkanes with CO and O₂ 5 Utilization of NO_x in Organic Synthesis 5.1 First Catalytic Nitration of Alkanes using NO₂ 5.2 Reaction of NO with Organic Compounds 6 Sulfoxidation of Alkanes Catalyzed by Vanadium 7 Carbon‐Carbon Bond Forming Reaction via Catalytic Carbon Radicals Generated from Various Organic Compounds Assisted by NHPI 7.1 Oxyalkylation of Alkenes with Alkanes and Dioxygen 7.2 Synthesis of α‐Hydroxy‐γ‐lactones by Addition of α‐Hydroxy Carbon Radicals to Unsaturated Esters 7.3 Hydroxyacylation of Alkenes using 1,3‐Dioxolanes and Dioxygen 8 Conclusions     

Electronic Effect of Substituent of Quinones on their Catalytic Performance in Hydrocarbons Oxidation

Quinones with electron-withdrawing F, Cl or Br groups and N-hydroxyphthalimide (NHPI) were used as catalysts in selective oxidation of hydrocarbons with molecular oxygen as oxidant. The catalytic activity in the selective oxidation of ethylbenzene to oxygenation products was in the following order: p-benzoquinone < tetrafluoro-p-benzoquinone ≈ tetrachloro-p-benzoquinone < tetrabromo-p-benzoquinone (p-TBBQ). Moderate electron-withdrawing power of substituent was suitable for quinone abstracting hydrogen from NHPI to generate reactive phthalimido-N-oxyl (PINO). The catalytic activity of p-TBBQ/NHPI, the best catalyst in our study, was also tested in the selective oxidation of alkylarenes, alkenes and alkanes.     

Aerobic Oxidation of Cyclohexane using N‐Hydroxyphthalimide Bearing Fluoroalkyl Chains

The N‐hydroxyphthalimide derivatives, F₁₅‐ and F₁₇‐NHPI, bearing a long fluorinated alkyl chain, were prepared and their catalytic performances were compared with that of the parent compound, N‐hydroxyphthalimide (NHPI). The oxidation of cyclohexane under 10 atm of air in the presence of fluorinated F₁₅‐ or F₁₇‐NHPI, cobalt diacetate [Co(OAc)₂], and manganese diacetate [Mn(OAc)₂] without any solvent at 100 °C afforded a mixture of cyclohexanol and cyclohexanone (K/A oil) as major products along with a small amount of adipic acid. It was found that F₁₅‐ and F₁₇‐NHPI exhibit higher catalytic activity than NHPI for the oxidation of cyclohexane without a solvent. However, for the oxidation in acetic acid all of these catalysts afforded adipic acid as a major product in good yield and the catalytic activity of NHPI in acetic acid was almost the same as those of F₁₅‐ and F₁₇‐NHPI. The oxidation by F₁₅‐ and F₁₇‐NHPI catalysts in trifluorotoluene afforded K/A oil in high selectivity with little formation of adipic acid, while NHPI was a poor catalyst under these conditions, forming K/A oil as well as adipic acid in very low yields. The oxidation in trifluorotoluene by F₁₅‐ and F₁₇‐NHPI catalysts was considerably accelerated by the addition of a small amount of zirconium(IV) acetylacetonate [Zr(acac)₄] to the present catalytic system to afford selectively K/A oil, but no such effect was observed in the NHPI‐catalyzed oxidation in trifluorotoluene.     

交联聚苯乙烯微球负载N-羟基邻苯二甲酰亚胺催化剂对甲苯和环己醇氧化的催化性能

通过分子设计,以交联聚苯乙烯(CPS)微球为基质,制备了固载化的N-羟基邻苯二甲酰亚胺(NHPI)催化剂. 先将CPS微球氯甲基化,制得氯甲基化微球CMCPS,再使微球表面的氯甲基与偏苯三酸酐(TMA)分子中的羧基酯化反应,将邻苯二甲酸酐(PA)键合到聚合物微球表面,获得键合邻苯二甲酸酐的微球CPS-PA,使之与盐酸羟胺反应,制备固载NHPI的微球CPS-NHPI,固载量达2.25 mmol/g,并对其进行表征. 将CPS-NHPI分别用于分子氧氧化甲苯和环己醇过程,考察微球的催化活性,分析其催化氧化机理. 结果表明,以三乙胺为缚酸剂,采用极性溶剂N,N-二甲基乙酰胺,在110℃下CMCPS表面的氯甲基与TMA可顺利反应. 适宜条件下CMCPS氯甲基的转化率可达73%. CPS-NHPI-Co(OAc)2催化体系对分子氧氧化甲苯和环己醇的催化活性良好,为自由基链反应机理.