埃洛石表面修饰并负载salen钼高效催化烯烃环氧化反应

采用温和的化学表面改性和自组装方法成功制备了埃洛石纳米管负载salen钼(HNTs-SL-Mo)催化剂，运用透射电镜、X射线衍射、红外光谱、诱导偶合等离子体谱和X射线光电子能谱表征了催化剂的形态、大小和分散性等性质。结果证明了salen结构的存在和埃洛石配位钼催化剂的成功制备。制备的催化剂在各种烯烃的环氧化反应中均有很好的活性，且活性高于均相催化剂。对比实验表明，在固定MoO(O2)2(DMF)2时， salen结构发挥了重要作用，不能用N原子作为单一配体来代替。本文还推测了钼和salen配体可能的连接方式和该催化剂催化烯烃环氧化反应的机理。该催化剂在重复使用8次后其活性未见明显下降，表现出优异的重复使用性能。由于埃洛石是一种廉价易得的材料，因此它可为设计效果独特的催化剂提供一个选择。     

埃洛石表面修饰并负载salen钼高效催化烯烃环氧化反应（英文）

采用温和的化学表面改性和自组装方法成功制备了埃洛石纳米管负载salen钼(HNTs-SL-Mo)催化剂,运用透射电镜、X射线衍射、红外光谱、诱导偶合等离子体谱和X射线光电子能谱表征了催化剂的形态、大小和分散性等性质.结果证明了salen结构的存在和埃洛石配位钼催化剂的成功制备.制备的催化剂在各种烯烃的环氧化反应中均有很好的活性,且活性高于均相催化剂.对比实验表明,在固定Mo O(O2)2(DMF)2时,salen结构发挥了重要作用,不能用N原子作为单一配体来代替.本文还推测了钼和salen配体可能的连接方式和该催化剂催化烯烃环氧化反应的机理.该催化剂在重复使用8次后其活性未见明显下降,表现出优异的重复使用性能.由于埃洛石是一种廉价易得的材料,因此它可为设计效果独特的催化剂提供一个选择.     

胺功能化的拟薄水铝石纳米颗粒负载的Mn-V复合物:高效的烯烃环氧化催化剂（英文）

将具有高比表面积和表面高度羟基化的拟薄水铝石纳米颗粒与3-(3甲氧基硅烷)-正丙胺进行共价结合而官能团化,再用于负载硫酸氧钒和六羰基钼络合物。所得样品采用红外光谱、粉末X射线衍射、热重-差热分析、X射线光电子能谱、元素分析、电感耦合等离子体和透射电镜等技术进行了表征,并用于顺-环辛烯的环氧化反应中,优化了诸如溶剂和氧化剂等反应条件.反应过程采用气-液色谱进行监测.重复使用实验表明,该纳米催化剂可重复使用多次,并保持顺-环辛烯接近完全环氧化.所得到的优化反应条件也成功用于其它的取代烯烃的环氧化反应中.     

胺功能化的拟薄水铝石纳米颗粒负载的Mn-V复合物：高效的烯烃环氧化催化剂

将具有高比表面积和表面高度羟基化的拟薄水铝石纳米颗粒与3-(3甲氧基硅烷)-正丙胺进行共价结合而官能团化,再用于负载硫酸氧钒和六羰基钼络合物。所得样品采用红外光谱、粉末X射线衍射、热重-差热分析、X射线光电子能谱、元素分析、电感耦合等离子体和透射电镜等技术进行了表征,并用于顺-环辛烯的环氧化反应中,优化了诸如溶剂和氧化剂等反应条件。反应过程采用气-液色谱进行监测。重复使用实验表明,该纳米催化剂可重复使用多次,并保持顺-环辛烯接近完全环氧化。所得到的优化反应条件也成功用于其它的取代烯烃的环氧化反应中。     

Y型分子筛固载Co(Salprn)配合物的制备及催化烯烃环氧化性能

采用自由配体法将双水杨醛缩丙二胺席夫碱钴配合物Co(Salprn)封装于Y型分子筛超笼中,并通过X射线衍射、漫反射UV-Vis光谱、FT-IR光谱和差热分析技术对所制备的催化剂进行了表征。该催化剂样品( [Co(Salprn)]-Y)在苯乙烯环氧化反应中较纯配合物Co(Salprn)表现出很高的催化活性。反应条件（包括溶剂、催化剂用量、异丁醛浓度和反应时间）对催化性能有较大影响。研究结果还表明,[Co(Salprn)]-Y对其他烯烃的环氧化也具有较高催化活性。其活性顺序为苯乙烯﹥环己烯﹥环辛烯﹥正辛烯。     

纳米SnO2高效催化烯烃与H2O2环氧化反应研究

构建了用于催化烯烃与过氧化氢环氧化反应的高效、 绿色催化反应体系. 首先, 通过水热合成法制备了纳米SnO₂, 并在320 ℃下煅烧. 随后, 对所有催化剂进行X射线衍射(XRD)、 紫外-可见漫反射光谱(UV-Vis)、 傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征. 进一步将催化剂用于以H₂O₂水溶液为氧化剂环氧化各种官能化烯烃(包括环烯烃, 苯乙烯和直链烯烃)的反应, 以高转化率和高选择性得到了环氧化物. 在相似的反应条件下, 发现合成的纳米SnO₂-170催化剂在催化1-甲基环己烯与H₂O₂的环氧化反应中的活性最佳, 在2 h内1-甲基环己烯的转化率达到100%, 环氧化物选择性达到100%.     

手性低聚环状salen-Mn(Ⅲ)配合物的合成及其催化烯烃不对称环氧化反应的性能

 合成了新型二水杨醛衍生物,将其与(1R,2R)-环己二胺缩合制备出手性低聚环状salen配体,该配体再与Mn3+配位制得手性低聚环状salen-Mn(Ⅲ)配合物. 利用核磁共振光谱、傅里叶变换红外光谱、紫外可见光谱、凝胶渗透色谱和元素分析等手段对配体和配合物进行了表征. 分别以NaClO和间氯过氧苯甲酸(m-CPBA)为氧化剂,考察了该salen-Mn(Ⅲ)配合物催化烯烃不对称环氧化反应的性能. 结果表明,该配合物对顺-β-甲基苯乙烯的不对称环氧化反应具有很好的催化性能,产物选择性达96%, ee值达78%. 以顺-β-甲基苯乙烯为底物,m-CPBA为氧化剂,考察了该配合物催化剂的循环使用性能.     

通过接枝苄基磺酸在MCM-41上固载手性Mn(salen)配合物

首先通过两步后合成处理,在MCM-41上接枝苄基磺酸;然后,以苄基磺酸为过渡产物,用手性Mn(salen)配合物修饰处理,得到了苄基磺酸轴向负载手性Mn(salen)配合物的MCM-41;实现了在廉价且温和条件下均相手性Mn(salen)催化剂的非均相化。采用X射线衍射(XRD)、低温N₂吸附-脱附、红外光谱、热重-差示扫描量热(TG-DSC)分析、电感耦合等离子体发射光谱(ICP)和酸度滴定等对样品进行了表征。结果表明,手性Mn(salen)配合物成功固载在MCM-41上,且MCM-41的介孔结构和Mn(salen)配合物的手性特征仍然保留。以间氯过氧苯甲酸为氧化剂,考察了所得固载型催化剂对α-甲基苯乙烯的不对称环氧化催化性能,结果表明在0 ℃反应2 h,催化剂用量为0.02 mmol,无需加入轴向配体N-甲基吗啉氮氧化物(NMO)的条件下对映体过量(enantiomeric excess,e.e.)值可达99%以上,转化率为77%。归因于苄基磺酸基起到了很好的轴向配体作用。经适当处理,固载型催化剂在循环使用5次后e.e.值依然有71%,表现出较好的活性和重复使用性能。     

通过接枝苄基磺酸在MCM-41上固载手性Mn(salen)配合物

首先通过两步后合成处理,在MCM-41上接枝苄基磺酸;然后,以苄基磺酸为过渡产物,用手性Mn(salen)配合物修饰处理,得到了苄基磺酸轴向负载手性Mn(salen)配合物的MCM-41;实现了在廉价且温和条件下均相手性Mn(salen)催化剂的非均相化。采用X射线衍射(XRD)、低温N2吸附-脱附、红外光谱、热重-差示扫描量热(TG-DSC)分析、电感耦合等离子体发射光谱(ICP)和酸度滴定等对样品进行了表征。结果表明,手性Mn(salen)配合物成功固载在MCM-41上,且MCM-41的介孔结构和Mn(salen)配合物的手性特征仍然保留。以间氯过氧苯甲酸为氧化剂,考察了所得固载型催化剂对α-甲基苯乙烯的不对称环氧化催化性能,结果表明在0℃反应2 h,催化剂用量为0.02 mmol,无需加入轴向配体N-甲基吗啉氮氧化物(NMO)的条件下对映体过量(enantiomeric excess,e.e.)值可达99%以上,转化率为77%。归因于苄基磺酸基起到了很好的轴向配体作用。经适当处理,固载型催化剂在循环使用5次后e.e.值依然有71%,表现出较好的活性和重复使用性能。     

离子液体中Mn(salen)催化环己烯环氧化反应

 研究了离子液体中Mn(salen)络合物催化环己烯的环氧化反应,考察了反应介质、 Mn(salen)络合物催化剂结构和反应条件等对环氧化反应的影响. 在离子液体-CH2Cl2混合溶剂中,以相对廉价的H2O2为氧化剂,得到了高的环己烯转化率和环氧环己烷选择性. 当以邻苯二胺和水杨醛制备的Mn(salen)络合物为催化剂,反应温度为273 K时,在［bmim］BF4-CH2Cl2的混合溶剂中,环己烯的转化率和环氧环己烷选择性分别可达100%和94.0%. 此外,反应结束后,产物可以由正己烷萃取出来,解决了传统均相催化体系中催化剂与产物不易分离的问题.     

Molybdenum hexacarbonyl supported on amine modified multi‐wall carbon nanotubes: an efficient and highly reusable catalyst for epoxidation of alkenes with tert‐butylhydroperoxide

In the present work, highly efficient epoxidation of alkenes catalyzed by Mo(CO)₆ supported on multi‐wall carbon nanotubes modified by 2‐aminopyrazine, APyz‐MWCNTs, is reported. The prepared catalyst was characterized by elemental analysis, scanning electron microscopy, FT IR and diffuses reflectance UV–vis spectroscopic methods. This new heterogenized catalysts, [Mo(CO)₆@APyz‐MWCNT], was used as a highly efficient catalyst for epoxidation of alkenes with tert‐BuOOH. This robust catalyst was reused several times without loss of its catalytic activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Mono-lacunary PrIII-Polyoxotungstate： Epoxidation of Alkenes with Unusual Selectivity

The utilization of polyoxometalates (POMs) or their derivatives as homogeneous or heterogeneous catalysts in alkene epoxidation is a subject of considerable research activity[1]. The limitation to the use of POMs in these catalytic reactions is either their relatively low selectivity in epoxide formation or applicability for a rather limited type of alkenes. Therefore, it would be beneficial if the catalysts bear high selectivity for epoxidation and are applicable for a rather wide variety of alkenes, which is desirable in industrial processes and also vital for the selection of an ideal catalyst[2]. In search for an efficient and practical epoxidation method to utilize aqueous H2O2 as terminal oxidant, we focus on the rare-earth complexes with lacunary POM ligands.     

Axially coordinated chiral salen Mn(iii) anchored onto azole onium modified ZnPS-PVPA as effective catalysts for asymmetric epoxidation of unfunctionalized olefins

A series of chiral salen Mn(iii) immobilized onto azole onium modified zinc poly(styrene-phenylvinyl phosphonate)-phosphate (ZnPS-PVPA) were prepared. The catalysts were characterized by FT-IR, diffusion reflection UV-vis, AAS, N(2) volumetric adsorption, SEM, TEM, XPS, XRD, TG and elemental analysis. The results showed that the chiral salen Mn(iii) complex was successfully immobilized onto ZnPS-PVPA. These prepared catalysts were evaluated in the asymmetric epoxidation of unfunctionalized olefins with m-CPBA and NaIO(4) as oxidants and demonstrated higher catalytic activities than those of the corresponding homogeneous chiral salen Mn(iii) catalyst under the same conditions. Moreover, these heterogeneous catalysts were stable and could be recycled nine times without significant loss of activity. Furthermore, this novel type of catalyst could also be validly used in large-scale reactions with superior catalytic disposition being maintained at the same level, which indicated the potential for applications in industry.     

Oxidation reactions catalysed by molybdenum(VI) complexes grafted on UiO‐66 metal–organic framework as an elegant nanoreactor

A heterogeneous catalyst was synthesized by immobilizing Mo(CO)₃ in a UiO‐66 metal–organic framework. The benzene ring of the organic linker in UiO‐66 was modified via liquid‐phase deposition of molybdenum hexacarbonyl, Mo(CO)₆, as starting precursor to form the (arene)Mo(CO)₃ species inside the framework. The structure of this catalyst was characterized using X‐ray diffraction, and chemical integrity was confirmed using Fourier transform infrared and diffuse reflectance UV–visible spectroscopic methods. The metal content was analysed with inductively coupled plasma. Field emission scanning electron microscopy was used to measure particle size and N₂ adsorption measurements to characterize the specific surface area. This catalytic system was efficiently applied for epoxidation of alkenes and oxidation of sulfides. The Mo‐containing metal–organic framework was reused several times without any appreciable loss of its efficiency.     

Efficient and Magnetically Recoverable “Click” PEGylated γ‐Fe2O3–Pd Nanoparticle Catalysts for Suzuki–Miyaura,Sonogashira, and Heck Reactions with Positive Dendritic Effects

The engineering of novel catalytic nanomaterials that are highly active for crucial carbon–carbon bond formations, easily recoverable many times, and biocompatible is highly desirable in terms of sustainable and green chemistry. To this end, catalysts comprising dendritic “click” ligands that are immobilized on a magnetic nanoparticle (MNP) core, terminated by triethylene glycol (TEG) groups, and incorporate Pd nanoparticles (PdNPs) have been prepared. These nanomaterials are characterized by transmission electron microscopy (TEM), high‐resolution TEM, inductively coupled plasma analysis, Fourier transform infrared spectroscopy, X‐ray photoelectron spectra and energy‐dispersive X‐ray spectroscopy. They are shown to be highly active, dispersible, and magnetically recoverable many times in Suzuki, Sonogashira, and Heck reactions. In addition, a series of pharmacologically relevant or natural products were successfully synthesized using these magnetic PdNPs as catalyst. For comparison, related PdNP catalysts deposited on MNPs bearing linear “click” PEGylated ligands are also prepared. Strong positive dendritic effects concerning ligand loading, catalyst loading, catalytic activity, and recyclability are observed, that is, the dendritic catalysts are much more efficient than non‐dendritic analogues.     

Encapsulation of a chiral MnIII(salen) complex in ordered mesoporous silicas: an approach towards heterogenizing asymmetric epoxidation catalysts for non-functionalized alkenes

Two immobilized chiral Mn^III(salen) complexes covalently anchored on modified MCM-41 (50 Å) and SBA-15 (75 Å) were prepared using 3-aminopropyltriethoxysilane as a reactive surface modifier to afford comparable or even higher enantioselectivity than homogeneous catalysts for the enantioselective epoxidation of a series of smaller to bulkier alkenes. The catalyst immobilized in silica with larger pore diameters was found to be more active. Compared to homogeneous catalysts, the heterogenized catalysts are more stable and can be recycled four times with retention of enantioselectivity.     

Effect of triarylphosphane ligands on the rhodium‐catalyzed hydrosilylation of alkene

A series of triarylphosphanes ( 1a , 2a , 3a , 4a , 5a , 6a , 7a , 8a , 9a , 10a , 11a ) have been synthesized. An X‐ray crystal structure analysis of (2‐bromophenyl)diphenylphosphane ( 1a ) unambiguously confirmed the constitution of the functionalized phosphane. The hydrosilylation reaction of styrene with triethoxysilane catalyzed with RhCl₃/triarylphosphane was studied. In comparison with the classic Wilkinson's catalyst, rhodium complexes with functionalized triarylphosphane ligands are characterized by a very high catalytic effectiveness for the hydrosilylation of alkene. Among these catalysts tested, RhCl₃/diphenyl(2‐(trimethylsilyl)phenyl)phosphane ( 8a ) exhibited excellent catalytic properties. Using this silicon‐containing phosphane ligand for the rhodium‐catalyzed hydrosilylation of styrene, both higher conversion of alkene and higher β‐adduct selectivity were obtained than with Wilkinson's catalyst. Copyright © 2014 John Wiley & Sons, Ltd.     

Enhanced epoxidation of soybean oil by novel Al2O3–ZrO2–TiO2 solid acid catalyst

This study aims to develop highly efficient, recyclable solid catalysts for the epoxidation of vegetable oils. An Al₂O₃–ZrO₂–TiO₂ solid acid catalyst was prepared by a co‐precipitation/impregnation method and characterised through scanning electron microscopy, energy‐dispersive spectroscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared and nitrogen adsorption–desorption analyses. The solid acid catalyst with a high surface area and typical slit pore adsorption was successfully synthesised. Al₂O₃–ZrO₂–TiO₂ also exhibits high stability and improved catalytic efficiency in the epoxidation of soybean oil. An oil conversion rate of 86.6%, which is higher than that of conventional catalysts, was obtained with a catalyst loading of 0.8 wt% and was maintained at 76.6% even after recycling the catalyst three times. The performance of the solid catalyst was slightly superior to that of H₂SO₄. Therefore, this novel catalyst may potentially be applicable in catalysing soybean oil epoxidation.     

Synthesis and characterization of a new kind of immobilized Mn(salen) and catalytic epoxidation of styrene on the catalyst

A linear polystyrene‐isopropenyl phosphonic acid (PS‐IPPA) copolymer was newly synthesized by free radical reaction in solution with isopropenyl phosphonic acid (IPPA) and styrene. Zirconium poly(styrene‐isopropenyl phosphonate)‐phosphate acid (ZPS‐IPPA) was also synthesized. The benzene rings of ZPS‐IPPA were hydroxylated and then further reacted with Mn(salen)Cl. Thus the heterogeneous catalyst, Mn(salen) axially immobilized onto ZPS‐IPPA was synthesized. These substances were characterized by IR spectra, X‐ray diffraction (XRD), SEM, TEM, NMR, thermogravimetric analysis, and AAS. The catalyst showed good activity to epoxidation of styrene, which is close to that of the corresponding homogeneous catalyst. Copyright © 2008 John Wiley & Sons, Ltd.     

A route to magnetically separable nanocatalysts: Combined experimental and theoretical investigation of alkyl substituent role in ligand backbone towards epoxidation ability

We have prepared two chiral Schiff base ligands, H₂L¹ and H₂L², and one achiral Schiff base ligand, H₂L³, by treating 2,6‐diformyl‐4‐methylphenol separately with (R )‐1,2‐diaminopropane, (R )‐1,2‐diaminocyclohexane and 1,1′‐dimethylethylenediamine, in ethanolic medium, respectively. The complexes MnL¹ClO₄ ( 1 ), MnL²ClO₄ ( 2 ), MnL³ClO₄ ( 3 ), FeL¹ClO₄ ( 4 ), FeL²ClO₄ ( 5 ) and FeL³ClO₄ ( 6 ) have been obtained by reacting the ligands H₂L¹, H₂L² and H₂L³ with manganese(III) perchlorate or iron(III) perchlorate in methanol. Circular dichroism studies suggest that ligands H₂L¹ and H₂L² and their corresponding complexes have asymmetric character. Complexes 1 – 6 have been used as homogeneous catalysts for epoxidation of alkenes. Manganese systems have been found to be much better than iron counterparts for alkene epoxidation, with 3 as the best catalyst among manganese systems and 6 as the best among iron systems. The order of their experimental catalytic efficiency has also been rationalized by theoretical calculations. We have observed higher enantiomeric excess product with catalysts 1 and 4 , so they were attached to surface‐modified magnetic nanoparticles to obtain two new magnetically separable nanocatalysts, Fe₃O₄@dopa@MnL¹ and Fe₃O₄@dopa@FeL⁴. They have been characterized and their alkene epoxidation ability has been investigated. These catalysts can be easily recovered by magnetic separation and recycled several times without significant loss of catalytic activity. Hence our study focuses on the synthesis of a magnetically recoverable asymmetric nanocatalyst that finds applications in epoxidation of alkenes and at the same time can be recycled and reused.