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We describe herein a highly elegant and suitable synthesis of amide products from alcohols and amines through a tandem oxidation process that uses molecular oxygen as a terminal oxidant. Carbon‐black‐stabilized polymer‐incarcerated gold (PICB‐Au) or gold/cobalt (PICB‐Au/Co) nanoparticles were employed as an efficient heterogeneous catalyst depending on alcohol reactivity and generated only water as the major co‐product of the reaction. A wide scope of substrate applicability was shown with 42 examples. The catalysts could be recovered and reused without loss of activity by using a simple operation. 相似文献
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Selective oxidation of amines using oxygen as terminal oxidant is an important area in green chemistry. In this work, we describe the use of graphite‐supported gold nanoparticles (AuNPs/C) to catalyze aerobic oxidation of cyclic and acyclic benzylic amines to the corresponding imines with moderate‐to‐excellent substrate conversions (43–100 %) and product yields (66–99 %) (19 examples). Oxidation of N‐substituted 1,2,3,4‐tetrahydroisoquinolines in the presence of aqueous NaHCO3 solution gave the corresponding amides in good yields (83–93 %) with high selectivity (up to amide/enamide=93:4) (6 examples). The same protocol can be applied to the synthesis of benzimidazoles from the reaction of o‐phenylenediamines with benzaldehydes under aerobic conditions (8 examples). By simple centrifugation, AuNPs/C can be recovered and reused for ten consecutive runs for the oxidation of dibenzylamine to N‐benzylidene(phenyl)methanamine without significant loss of catalytic activity and selectivity. This protocol “AuNPs/C+O2” can be scaled to the gram scale, and 8.9 g (84 % isolated yield) of 3,4‐dihydroisoquinoline can be obtained from the oxidation of 10 g 1,2,3,4‐tetrahydroisoquinoline in a one‐pot reaction. Based on the results of kinetic studies, radical traps experiment, and Hammett plot, a mechanism involving the hydrogen‐transfer reaction from amine to metal and oxidation of M‐H is proposed. 相似文献
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甲烷氧化菌素(methanobactin,mb)是具有过氧化氢还原酶活性的荧光肽.从甲基弯菌Methylosinus trichospo-rium IMV3011限铜培养介质中分离mb,采用紫外可见全波长扫描法观察mb催化对苯二酚还原氯金酸合成纳米金的作用和影响,当mb/氯金酸/对苯二酚反应液中mb的浓度分别是2.5×10-5mol/L、5.0×10-5mol/L和1.0×10-4mol/L时,形成的纳米金溶液的特征峰分别是561.5 nm(OD561=0.158)、548.0 nm(OD5 48=0.426)、536.5 nm(OD5 36=0.541),特征峰波长减小,对应的吸光值增大,表明mb能够催化对苯二酚还原氯金酸合成纳米金,并且可以通过调控mb的浓度控制纳米金的合成量及粒径大小. 相似文献
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Dr. Peng Liu Prof. Dr. Can Li Prof. Dr. Emiel J. M. Hensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):12122-12129
Efficient basic hydrotalcite (HT)‐supported gold nanoparticle (AuNP) catalysts have been developed for the aerobic oxidative tandem synthesis of methyl esters and imines from primary alcohols catalyzed under mild and soluble‐base‐free conditions. The catalytic performance can be fine‐tuned for these cascade reactions by simple adjustment of the Mg/Al atomic ratio of the HT support. The one‐pot synthesis of methyl esters benefits from high basicity (Mg/Al=5), whereas moderate basicity greatly improves imine selectivity (Mg/Al=2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies show a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidation of the starting alcohol but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the composition of the support has been shown to yield optimum AuNP catalysts for different tandem reactions. 相似文献
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Oxidation of Benzyl Alcohol and Carbon Monoxide Using Gold Nanoparticles Supported on MnO2 Nanowire Microspheres
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Dr. Mosaed Alhumaimess Dr. Zhongjie Lin Dr. Qian He Dr. Li Lu Dr. Nickolaos Dimitratos Dr. Nicholas F. Dummer Dr. Marco Conte Dr. Stuart H. Taylor Dr. Jonathan K. Bartley Prof. Christopher J. Kiely Prof. Graham J. Hutchings 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1701-1710
MnO2 was synthesised as a catalyst support material using a hydrothermal method. This involved reacting MnSO4 ? H2O and (NH4)2S2O8 at 120 °C for a range of crystallisation times, which affords control over the morphology and phase composition of the MnO2 formed. Gold was deposited on these supports using sol‐immobilisation, impregnation and deposition precipitation methods, and the resultant materials were used for the oxidation of benzyl alcohol and carbon monoxide. The effect of the support morphology on the dispersion of the gold nanoparticles and the consequent effect on the catalytic performance is described and discussed. 相似文献
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Synthesis and Catalytic Reactions of Nanoparticles formed by Electrospray Ionization of Coinage Metals
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Anyin Li Qingjie Luo Prof. So‐Jung Park Prof. R. Graham Cooks 《Angewandte Chemie (International ed. in English)》2014,53(12):3147-3150
Noble metals can be ionized by electrochemical corrosion and transported by electrospray ionization. Mass spectrometry (MS) showed solvated metal ions as the main ionic constituent of the sprayed droplets. Collection of the electrospray plume on a surface yielded noble metal nanoparticles (NPs) under ambient conditions. The NPs were characterized by several techniques. Under typical conditions, capped‐nanoparticle sizes averaged 2.2 nm for gold and 6.5 nm for silver. The gold nanoparticles showed high catalytic activity in the reduction of p‐nitrophenol by NaBH4. Efficient catalysis was also observed by simply directing the spray of solvated Au+ onto the surface of an aqueous p‐nitrophenol/NaBH4 mixture. Organometallic ions were generated by spiking ligands into the spray solvent: for example, CuI bipyridine cations dominated the spray during Cu electrocorrosion in acetonitrile containing bipyridine. This organometallic reagent was shown to be effective in the radical polymerization of styrene. 相似文献
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Mohannad T. Aljarrah Alaa M. Alboull Mohammad S. Alharahsheh Azad Ashraf Amith Khandakar 《Molecules (Basel, Switzerland)》2022,27(24)
The synthesis of gold nanoparticles (GNPs) using chemical reduction in batch and microreactor methods has been reported. A parametric study of the effect of several parameters on the size of gold nanoparticles was performed in batch synthesis mode using the modified Martin method. The best-obtained conditions were used to synthesize gold nanoparticles using a glass chip microreactor, and the size of the resulting GNPs from both methods was compared. The presence of polyvinyl alcohol (SC) was used as a capping agent, and sodium borohydride (SB) was used as a reducing agent. Several parameters were studied, including HAuCl4, SC, SB concentrations, the volumetric ratio of SB to gold precursor, pH, temperature, and mixing speed. Various techniques were used to characterize the resulting nanoparticles, including Atomic Absorbance spectroscopy (AAS), Ultraviolet-visible spectroscopy (UV-Vis), and dynamic light scratching (DLS). Optimum conditions were obtained for the synthesis of gold nanoparticles. Under similar reaction conditions, the microreactor consistently produced smaller nanoparticles in the range of 10.42–11.31 nm with a reaction time of less than 1 min. 相似文献
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Dr. Rosaria Ciriminna Dr. Ermelinda Falletta Prof. Cristina Della Pina Dr. Joaquim Henrique Teles Dr. Mario Pagliaro 《Angewandte Chemie (International ed. in English)》2016,55(46):14210-14217
Gold catalysis has recently found its first large‐scale applications in the chemical industry. This Minireview provides a critical analysis of the success factors and of the main obstacles that had to be overcome on the long way from the discovery to the commercialization of gold catalysts. The insights should be useful to researchers in both academia and industry working on the development of tomorrow's gold catalysts to tackle significant environmental and economic issues. 相似文献
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可见光催化作为一种新兴且强大的有机合成手段,具有洁净节能、优秀的官能团兼容性和良好的化学选择性等特征。氧气作为一种廉价、无污染的氧化剂,与可见光催化相结合,极大地促进了绿色化学的发展。本文主要对我们课题组近年来在可见光需氧氧化领域取得的成果做了简明的综述,并对其发展进行了展望。 相似文献
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Aila Jimenez‐Ruiz Prof. Pilar Perez‐Tejeda Prof. Elia Grueso Dr. Paula M. Castillo Prof. Rafael Prado‐Gotor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9596-9609
Since Faraday first described gold sol synthesis, synthetic routes to nanoparticles, as well as their applications, have experienced a huge growth. Variations in synthesis conditions such as pH, temperature, reduction, and the stabilizing agent used will determine the morphology, size, monodispersity, and stability of nanoparticles obtained, allowing for modulation of their physical and chemical properties. Although many studies have been made about the synthesis and characterization of individual nanosystems of interest, to our knowledge the common, general traits that all those synthesis share have not been previously compiled. In this review, we aim to offer a global vision of some of the most relevant synthetic procedures reported up to date, with a special focus on nonfunctionalized gold nanoparticle synthetic routes in aqueous media, and to display a broad overview of the influence that synthesis conditions have on the shape, stability, and reactivity of nanoparticle systems. 相似文献
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Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity,Stability, and Temperature‐ Dependent Activation Properties
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Dr. Takuya Yoshida Prof. Dr. Toru Murayama Prof. Dr. Norihito Sakaguchi Prof. Dr. Mitsutaka Okumura Prof. Dr. Tamao Ishida Prof. Dr. Masatake Haruta 《Angewandte Chemie (International ed. in English)》2018,57(6):1523-1527
Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs4[α‐SiW12O40]?n H2O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was ?67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Auδ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions. 相似文献
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Gold Nanoparticles Supported on a Layered Double Hydroxide as Efficient Catalysts for the One‐Pot Synthesis of Flavones
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Takafumi Yatabe Dr. Xiongjie Jin Dr. Kazuya Yamaguchi Prof. Dr. Noritaka Mizuno 《Angewandte Chemie (International ed. in English)》2015,54(45):13302-13306
Flavones are a class of natural products with diverse biological activities and have frequently been synthesized by step‐by‐step procedures using stoichiometric amounts of reagents. Herein, a catalytic one‐pot procedure for the synthesis of flavone and its derivatives is developed. In the presence of gold nanoparticles supported on a Mg‐Al layered double hydroxide (Au/LDH), various kinds of flavones can be synthesized starting from 2′‐hydroxyacetophenones and benzaldehydes (or benzyl alcohols). The present one‐pot procedure consists of a sequence of several reactions, and Au/LDH can catalyze all these different types of reactions. The catalysis is shown to be truly heterogeneous, and Au/LDH can be readily recovered and reused. 相似文献