可重复使用CuO纳米粒子催化微波辅助的腈和NaN3环加成反应 合成5-取代1H-四唑类

将可重复使用的CuO纳米粒子成功用于催化微波辅助的腈和NaN3[3+2]环加成反应高效合成5-取代1H-四唑类化合物.该法突出特点为成本低、合成快、稳定性高、可重复使用、反应条件温和、无需任何添加物、官能团兼容性好和产率高.这种环境友好的微波辅助纳米粒子催化合成策略可望替代现有的涉及常规路易斯酸催化剂方法,以及作为一种简易的合成特殊化合物的方法.     

水滑石负载钯催化剂上的醇无氧脱氢反应

 研究了多种载体负载 Pd 催化剂上苯甲醇无氧脱氢反应. 结果发现, 以兼具较强酸性和碱性的水滑石 (HT) 为载体时, Pd 催化剂具有优异的苯甲醇转化活性和苯甲醛选择性, 当 Pd 含量为 0.32%~0.55% 时催化性能最佳. Pd/HT 催化剂可重复使用, 且对于含推电子取代基的芳香醇、2-噻吩甲醇、α,β-不饱和醇与环状脂肪醇等的直接脱氢反应均具有较好催化性能. HT 表面的 Pd(II) 物种反应后转变为平均粒径为 2.0~2.5 nm 的 Pd 纳米粒子或纳米簇. 具有较高分散度的 Pd(II) 物种易转变为较小的 Pd 纳米粒子, 从而具有较佳的催化性能. 本文推测, 催化剂表面的碱性位可促进苯甲醇 O–H 键的活化, 形成 Pd-苯甲氧基中间体, 该中间体进一步脱氢生成苯甲醛和 Pd-H 物种; 而催化剂表面的质子酸位可与 Pd-H 作用, 促进 H2 的脱除.     

酰胺羰基化反应中可重复使用的Pd/HZSM-5催化剂

 合成了非均相Pd/HZSM-5催化剂并将其用于酰胺羰基化反应. 结果表明,文献报道的Pd/C催化剂重复使用时其活性降为原来的一半,而Pd/HZSM-5催化剂重复使用4次后活性基本不变. 反应前后两种催化剂的TEM电镜照片表明, Pd/C上的金属钯粒子在反应后团聚并形成网络状结构,而Pd/HZSM-5上钯粒子在反应后仍保持与反应前相同的均匀分布状态.     

硫醚功能化离子液体固定纳米金粒子的制备及其催化性能

合成了一种新型的硫醚功能化离子液体(TFIL),以其为稳定剂在1-甲基-3-丁基咪唑六氟磷酸离子液体中制备了TFIL固定的纳米金粒子(GNP-TFIL)催化剂.采用红外光谱、紫外-可见光谱和透射电子显微镜等方法对GNP-TFIL催化剂进行了表征.结果表明,TFIL在固定纳米金粒子之后仍保持着离子液体的基本结构;纳米金粒子的分布均匀,粒径为2.0～3.6nm.GNP-TFIL催化剂对苯乙烯环氧化反应具有较高的催化活性,且可以重复使用.在45℃下反应6h时,苯乙烯的转化率和环氧苯乙烷的选择性分别可达100%和88.5%.     

可重复使用CuO纳米粒子催化微波辅助的腈和NaN_3环加成反应合成5-取代1H-四唑类（英文）

将可重复使用的CuO纳米粒子成功用于催化微波辅助的腈和NaN_3[3+2]环加成反应高效合成5-取代1H-四唑类化合物.该法突出特点为成本低、合成快、稳定性高、可重复使用、反应条件温和、无需任何添加物、官能团兼容性好和产率高.这种环境友好的微波辅助纳米粒子催化合成策略可望替代现有的涉及常规路易斯酸催化剂方法,以及作为一种简易的合成特殊化合物的方法.     

Pd(OH)2纳米粒子的制备、结构表征及其在HBIW催化氢解中的应用

2,4,6,8,10,12－六硝基－2,4,6,8,10,12－六氮杂异伍兹烷（HNIW）作为目前威力最大的单质炸药,日益受到各国国防和航空工业的重视^[1,2]。HNIW的合成,大体上分为缩合、催化氢解和硝化三步。在原料2,4,6,8,10,12－六氯杂异伍兹烷（HNIW）作为目前威力 最大的单质炸药,日前受到各国国防和航空工业的重视^[1,2]。HNIW的合成,大体上分为缩合、催化氢解和硝化三步。在原料2,4,6,8,10,12－六苄基－2,4,6,8,10,12-氮杂异伍兹烷（HBIW,化合物1）催化氢解中,催化剂Pd(OH)2/C因制备和回收工艺繁锁而成本较高,是造成HNIW生产成本居高不下的主要原因^[3]。改进催化氢解的催化剂,对HNIW的工业化生产具有重要意义。很多催化剂的催化效率随催化剂颗粒减小到纳米量级而显著提高[4,5],Pd(OH)2纳米粒子催化活性可望超过Pd(OH2)/C催化剂,用于催化氢解中。本文用共沸蒸馏法对自制的水合Pd(OH)2进行脱水处理,首次制得了Pd(OH)2纳米粒子。采用高分辨率透射电镜、激光动态光散射、紫外－可见吸收研究了Pd(OH)2纳米粒子的微观结构,并比较了Pd(OH)2纳米粒子和Pd(OH)2/C在化合物1催化氢解中的活性。     

中孔MCM-41负载Ru纳米粒子催化剂用于超声辐射下芳烃选择氧化反应

以中孔MCM-41为载体制得均一分散的粒径约5nm的Ru纳米粒子催化剂MCM-41-Ru,采用电感耦合等离子体、透射电镜、能量散射谱、X射线衍射和N2吸附-脱附法对其进行了表征,并将其作为可重复使用高效催化剂用于超声辅助芳烃选择氧化反应.结果表明,在超声辐射和KBrO3为氧化剂条件下,MCM-41-Ru催化剂加速了氧化反应,并以较高产率得到目的产物.回收的催化剂用于下次反应时活性保持不变,但其活性中心性质发生变化.     

绿色离子液体中纳米钯催化剂的制备及其催化Heck-Mizoroki反应性能

发展了在非卤素绿色离子液体1-丁基-3-甲基咪唑离子液体乳酸盐中制备纳米Pd催化剂的简便化学方法.透射电镜结果表明,Pd纳米粒子高度分散在[Bmim]Lac离子液体中,平均粒径为2.2–3.1 nm.Pd纳米粒子的大小随着体系中[Bmim]Lac与Pd(OAc)2摩尔比减小和温度升高而增大.考察了离子液体稳定纳米Pd催化剂(PdNPs@[Bmim]Lac)催化Heck-Mizoroki反应性能,并对反应条件进行了优化.结果表明,所制备的离子液体稳定的纳米Pd催化剂在优化条件下可高效催化系列卤代芳烃与烯烃的Heck-Mizoroki反应,且可循环使用6次.     

TiO_2-SiO_2纳米粒子的合成及二级散射光谱法测定核糖核酸

采用溶胶-凝胶法制备了TiO2-SiO2纳米粒子.通过X-射线衍射谱、透射电子显微镜等对纳米粒子进行了表征.研究了TiO2-SiO2纳米粒子与核糖核酸(RNA)的相互作用,建立了基于纳米粒子与RNA吸附反应,二级散射光谱法测定痕量RNA的新方法.方法的线性范围是0.005～5 mg/L; 检出限为1.46 μg/L.方法用于RNA合成样品的测定,回收率为99.4%～103.9%;相对标准偏差为019%～0.24%.     

MIL-101(Cr)-NH2负载Pd低温催化糠醛高选择性加氢生成四氢糠醇

随着资源枯竭和环境污染严重问题的凸显,生物质转化的研究越来越多,特别是生物质催化裂解制备生物燃料及高附加值的化学品.糠醛是一种半纤维素酸解的产物,也是生产糠醇、四氢糠醇、2-甲基呋喃、环戊酮等的重要原料.其中四氢糠醇既可以用于生产其他高附加值化学品,也可以用作生物燃料或者燃料添加剂.虽然Pd/MFI,Ni/SiO2,Pd-Ir/SiO2等催化剂均可用于糠醛选择加氢制备四氢糠醇,但是反应通常在高温高压条件下进行.为此我们希望找到一种在温和条件下使用的高效催化剂.MOF多孔材料具有丰富的孔道结构、极高的比表面积、表面可修饰的特点,还可与其他客体发生相互作用,进而影响催化性能.因此本课题组合成了一种含有氨基的MOF材料MIL-101(Cr)-NH2,进一步利用表面氨基吸附Pd的氯酸盐前体,经还原直接制得负载型催化剂Pd@MIL-101(Cr)-NH2,并用于糠醛选择加氢反应.本文采用X射线粉末衍射(PXRD)、热重分析(TG)、N2物理吸附-脱附、透射电镜(TEM)等手段表征了所制的MOFs和催化剂.通过将MIL-101(Cr)-NH2和不同Pd@MIL-101(Cr)-NH2的XRD谱与标准谱图对比,发现MIL-101(Cr)-NH2已成功合成,并在催化剂制备过程中和反应之后仍然保持稳定.TG结果表明,所制备MIL-101(Cr)-NH2在低于350 ℃C时结构不会被破环.MIL-101(Cr)-NH2的比表面积可达到1669 m2g?1,孔容达1.35 cm3g?1,从而为Pd纳米粒子均匀分散在载体上提供了可能性.各Pd@MIL-101(Cr)-NH2样品的TEM照片我们看出,Pd纳米粒子可均匀分散在MIL-101(Cr)-NH2上,粒径为3?4 nm.对比实验表明,氨基与金属的相互作用有利于Pd纳米粒子分散均匀.将Pd@MIL-101(Cr)-NH2用于糠醛选择加氢反应时,在40 ℃C,2 MPa H2的温和条件下,反应6 h后糠醛完全转化为四氢糠醇其选择性接近100%.表现出比文献报导的更加优异的催化性能.这得益于高度均匀分散的Pd纳米粒子,以及催化剂载体与Pd纳米粒子的配位作用和π-π相互作用.结果还表明当高于80℃C反应时,即有副产物生成,进一步提高反应温度会促进环戊酮的生成.可见,Pd@MIL-101(Cr)-NH2所表现的低温高加氢活性对提高四氢糠醇选择性至关重要.     

Biosynthesis of Highly Dispersed Palladium Nanoparticles Using Astraglmanna Aqueous Extract

Biosynthesis of nanoparticles has received increased attention due to a growing need to develop environmentally benign technologies in material synthesis and employment of secondary metabolites from plant extract that has emerged as a novel technology for this purpose. In this study, a rapid and biogenic process for fabrication of palladium nanoparticles (PdNPs) is reported. Highly dispersed palladium nanoparticles were successfully prepared by using aqueous extract of Astraglmanna, a non‐toxic and eco‐friendly material, without extra surfactant, capping agent, and template. The PdNPs were characterized by using UV—Visible spectroscopy, scanning electron microscope ‐ energy dispersive spectra (SEM‐EDX), Fourier transform infra red spectroscopy (FTIR), dynamic light scattering (DLS) and X‐ray diffraction (XRD) analysis. Transmission electron microscopic (TEM) images of the PdNPs were recorded and mean size of the biosynthesized nanoparticles was found to be approximately 15 nm.     

Green synthesis of palladium nanoparticles using Hibiscus sabdariffa L. flower extract: Heterogeneous and reusable nanocatalyst in Suzuki coupling reactions

An elementary and ecological method has been designed for the biosynthesis of palladium nanoparticles, through the utilization of aqueous extract of red tea (Hibiscus sabdariffa L.) as a reducing and stabilizing agent. The nanoparticles obtained were characterized through UV–visible spectroscopy, transmission election microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning election microscopy, energy‐dispersive X‐ray analysis and inductively coupled plasma analysis. The nanoparticles with spherical shape and dimensions of approximately 10 nm were used as a heterogeneous catalyst for Suzuki coupling reactions under mild conditions. The high efficiency of the catalytic reaction was affirmed by the good yields of products, easy work‐up, absence of palladium leached from the support and smooth recovery of catalyst.     

Green and effective route for the synthesis of monodispersed palladium nanoparticles using herbal tea extract (Stachys lavandulifolia) as reductant,stabilizer and capping agent,and their application as homogeneous and reusable catalyst in Suzuki coupling reactions in water

A simple and eco‐friendly procedure has been devised for the green synthesis of palladium nanoparticles, using the aqueous extract of herbal tea (Stachys lavandulifolia), a renewable and nontoxic natural phyto‐exudate. The water‐soluble components of the extract act as reducing agent and stabilizer. This green route does not require a surfactant or capping agent for the growth of palladium nanoparticles. The generated nanoparticles were analysed using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray analysis and inductively coupled plasma. The palladium nanoparticles having spherical shape and dimensions of between 5 and 7 nm were employed as a homogeneous catalyst for Suzuki coupling reactions conducted in water under mild conditions. Good yields of products, a facile work‐up, no evidence of leached palladium from the catalyst surface and smooth recovery of the catalysis by adding ethyl acetate, which could be reused at least eight times, confirm the very good efficiency of the catalytic reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Silica–acetylacetone‐supported palladium nanoparticles as an efficient and reusable catalyst in the Heck–Mizoroki C–C cross‐coupling reaction

The preparation of palladium nanoparticles supported on acetylacetone‐modified silica gel and their catalytic application for Heck olefination of aryl halides were investigated. The catalyst was characterized using X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission and scanning electron microscopies. The supported palladium nanoparticles are demonstrated to be a highly active and reusable catalyst for the Heck reaction. Several reaction parameters, including type and amount of solvent and base, were evaluated. The heterogeneity of the catalytic system was investigated with results indicating that there is a slight palladium leaching into the reaction solution under the applied reaction conditions. Despite this metal leaching, the catalyst can be reused nine times without significant loss of catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Behavior of Palladium Nanoparticles in the Absence or Presence of Cobalt Tetraaminophthalocyanine for the Electrooxidation of Hydrazine

We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly‐CoTAPc‐GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs‐GCE and PdNPs/poly‐CoTAPc‐GCE, respectively. PdNPs/poly‐CoTAPc‐GCE showed the best activity for the oxidation of hydrazine at the lowest potential of ?0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly‐CoTAPc‐GCE compared to PdNPs‐GCE. The catalytic rate constant for hydrazine oxidation was 6.12×10⁸ cm³ mol^?1 s^?1 using PdNPs/poly‐CoTAPc‐GCE.     

A simple,quick and novel protocol for biaryl synthesis using LiCl‐promoted in situ‐generated Pd nanoparticles

This paper describes a simple and a very quick protocol for biaryl synthesis using the Suzuki–Miyaura cross‐coupling reaction. A quintessential role of salting‐out agent LiCl was observed in the Suzuki–Miyaura cross‐coupling reaction that enhanced the reduction rate of Pd (II) to a considerable extent, resulting in the formation of nanosized palladium in a few seconds. The isolated Pd nanoparticles were characterized with X‐ray diffraction, dynamic light scattering, TGA, transmission electron microscopy and scanning electron microscopy‐dispersive X‐ray spectroscopy. The Suzuki–Miyaura cross‐coupling reaction proceeded very well with the in situ‐generated Pd nanocatalysts furnishing the desired biaryl adducts with excellent yields.     

Greener approach for synthesis of monodispersed palladium nanoparticles using aqueous extract of green tea and their catalytic activity for the Suzuki–Miyaura coupling reaction and the reduction of nitroarenes

A facile and green route for the synthesis of palladium nanoparticles (NPs) was developed utilizing non‐toxic and renewable natural green tea extract as the reducing, stabilizing and capping agent. The as‐prepared Pd‐NPs@G.Tea extract was characterized using UV–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. The Pd‐NPs@G.Tea extract could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties, and also for the reduction of nitroarenes using sodium borohydride in an environmentally friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity.     

Biosynthesis of palladium nanoparticles using Rosa canina fruit extract and their use as a heterogeneous and recyclable catalyst for Suzuki–Miyaura coupling reactions in water

A facile and green route for the synthesis of palladium nanoparticles was developed utilizing non‐toxic and renewable natural Rosa canina fruit extract as the reducing, stabilizing and capping agent, and they were applied as a heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties in water under moderate reaction conditions. The structural investigation of the generated nanoparticles was performed with UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy‐dispersive X‐ray analysis. The method has some advantages such as high yields, efficiency, elimination of surfactant, chemical reductants, ligand and organic solvent, economic, cleaner reaction profiles, heterogeneous catalysis, simple methodology and easy workup. The catalyst can be recovered and reused seven times without any significant decrease in catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Palladium on magnetic Irish moss: A new nano‐biocatalyst for suzuki type cross‐coupling reactions

A novel heterogeneous magnetic palladium nano‐biocatalyst was designed by utilizing Irish moss, a family of sulfated polysaccharides extracted from algae, as a natural biopolymer. This magnetic Irish moss decorated with palladium (Pd–Fe₃O₄@IM) to form a biomagnetic catalytic system was synthesized and well characterized by FT–IR analysis, X‐ray powder diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. The catalyst was stable to air and moisture and displayed high catalytic activity in ligand‐free Suzuki–Miyaura cross‐coupling reactions conducted under green chemistry reaction conditions. The aromatic ketones are produced by the cross‐coupling reaction between acid chlorides and aryl boronic acid derivatives in high yields.     

Biosynthesis of palladium nanoparticles as a heterogeneous and reusable nanocatalyst for reduction of nitroarenes and Suzuki coupling reactions

A facile and green route for the synthesis of palladium nanoparticles (Pd‐NPs) was developed utilizing non‐toxic and renewable natural green tea extract as the reducing, stabilizing and capping agent. The as‐prepared Pd‐NPs@Oak Gum catalyst was characterized using UV–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X‐ray spectroscopy. The Pd‐NPs@Oak Gum catalyst could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties and also for the reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.