- A Cu-Doped ZIF-8 metal organic framework as a heterogeneous solid catalyst for aerobic oxidation of benzylic hydrocarbons
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Mixed-metal metal organic frameworks have received considerable attention in recent years and it has been shown that the activity of the parent metal organic framework (MOF) is often enhanced upon doping with external metal ions within the framework. In this context, Cu2+ ions with different loadings were incorporated within the ZIF-8 framework to obtain a series of Cu-doped ZIF-8 materials and their activity was examined in the aerobic oxidation of hydrocarbons. The as-synthesized Cu-doped solids were characterized by powder X-ray diffraction (XRD), ultraviolet diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM), Fourier Transform infrared (FT-IR), electron paramagnetic resonance (EPR) and inductively coupled plasma (ICP) analysis. The experimental results revealed that the activity of Cu-doped ZIF-8 is much higher than that of the parent ZIF-8 in all the tested substrates at 120 °C. Furthermore, the activity of the Cu-doped ZIF-8 with the highest Cu loading was eight fold higher than that of the parent ZIF-8 in the aerobic oxidation of cyclooctane (1) at 120 °C with more than 80% selectivity to the corresponding cyclooctanol/cyclooctanone (ol/one) mixture. Cu-doped ZIF-8 was reused two times with no significant drop in its activity under identical conditions. Furthermore, comparison of the two times reused solid with that of the fresh solid by powder XRD and SEM analysis revealed identical structural integrity and morphology, respectively during the oxidation reactions.
- Nagarjun, Nagarathinam,Dhakshinamoorthy, Amarajothi
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supporting information
p. 18702 - 18712
(2019/12/09)
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- Synthesis, crystal structure and immobilization of a new cobalt(ii) complex with a 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand on modified magnetic nanoparticles as a catalyst for the oxidation of alkanes
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A new Co(ii) complex with formula [Co(tptz)Cl2]·2H2O (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) has been synthesized and characterized by X-ray crystallography, elemental analyses and spectroscopic methods. It was then supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3-aminopropyl)trimethoxysilane (APTMS) and designated as a Fe3O4@SiO2@APTMS@complex nanocatalyst. The prepared nanocatalyst was characterized by means of FT-IR, Raman, XPS, EDX, XRD, VSM, SEM and TEM studies. The catalytic activity of the [Co(tptz)Cl2]·2H2O complex and Fe3O4@SiO2@APTMS@complex designated as catalysts A and B was used for oxidation of activated secondary alkanes such as fluorene, diphenyl methane, ethylbenzene, cyclooctane and adamantane. Observation of 39-99% conversions and 27-100% selectivities toward the corresponding ketones as well as the heterogeneity and reusability of the catalyst B seem promising.
- Azarkamanzad, Zahra,Farzaneh, Faezeh,Maghami, Mahboobeh,Simpson, Jim
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p. 12020 - 12031
(2019/08/07)
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- "ship in a bottle" Porph@MOMs as highly efficient catalysts for selective controllable oxidation and insights into different mechanisms in heterogeneous and homogeneous environments
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In the present work, three "ship in a bottle" Porph@MOMs are reported as biomimetic oxidation catalysts for different reactions. These frameworks are constructed from trimesic acid and metal ions (M = Fe, Co and Mn) in which tetra(N-methyl-4-pyridyl)porphyrin (MTMPyP) is encapsulated within the cavities. Additionally, the catalytic activities of the corresponding homogeneous compounds, FeTMPyP, CoTMPyP and MnTMPyP, and the frameworks without porphyrins within the cavities were investigated in the foregoing oxidation reactions. The prepared 3D porous structures have the ability to control selectivity toward the desired product. Furthermore, they are capable of acting as effective peroxidase mimics, which successfully catalyze the oxidation of diverse olefins as well as hydrocarbons using TBHP as an oxidant. The heterogeneous catalysts significantly enhance conversion in contrast to their corresponding homogeneous systems. Remarkably, an insight into the catalyst behavior was gained from the proposed mechanism based on the reversal of selectivity. Investigation of the stability and reusability of the catalysts revealed the heterogeneity character of the catalyst with no desorption during the course of oxidation reactions. The high yields, clean reactions, high thermal stability and reusability of the catalysts make them good candidates for heterogeneous catalysts in various oxidation reactions.
- Saghian,Dehghanpour,Sharbatdaran
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p. 12872 - 12881
(2018/08/01)
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- Alkane oxidation catalysed by a self-folded multi-iron complex
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A preorganised ligand scaffold is capable of coordinating multiple Fe(II) centres to form an electrophilic CH oxidation catalyst. This catalyst oxidises unactivated hydrocarbons including simple, linear alkanes under mild conditions in good yields with selectivity for the oxidation of secondary CH bonds. Control complexes containing a single metal centre are incapable of oxidising unstrained linear hydrocarbons, indicating that participation of multiple centres aids the CH oxidation of challenging substrates.
- Mettry, Magi,Moehlig, Melissa Padilla,Gill, Adam D.,Hooley, Richard J.
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p. 120 - 128
(2016/11/09)
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- Ni-based catalysts derived from a metal-organic framework for selective oxidation of alkanes
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Ni nanoparticles embedded in nitrogen-doped carbon (Ni@C-N) materials were prepared by thermolysis of a Ni-containing metal-organic framework (Ni-MOF) under inert atmosphere. The as-synthesized Ni@C-N materials were characterized by powder X-ray diffraction, N2 adsorption-desorption analysis, scanning electron microscopy, transmission electron microscopy, atomic absorption spectroscopy, and X-ray photoelectron spectroscopy. The MOF-derived Ni-based materials were then examined as heterogeneous catalysts for the oxidation of alkanes under mild reaction conditions. The Ni@C-N composites displayed high activity and selectivity toward the oxidation of a variety of saturated C-H bonds, affording the corresponding oxidation products in good-to-excellent yields. Furthermore, the catalysts could be recycled and reused for at least four times without any significant loss in activity and selectivity under the investigated conditions.
- Zhou, Ying,Long, Jilan,Li, Yingwei
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p. 955 - 962
(2016/07/06)
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- Hydrocarbon oxidation catalyzed by self-folded metal-coordinated cavitands
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Functionalized cavitands have been shown to self-fold via coordination of Fe(ii) salts and effect catalytic C-H oxidation reactions of unfunctionalized alkanes under mild aqueous conditions in the presence of tert-butyl hydroperoxide as co-oxidant. Secondary and tertiary C-H bonds can be converted to ketones and alcohols, respectively, and ethers can be converted to esters. The cavitands retain the catalytic metal throughout the reaction, and can be recovered by filtration. The Royal Society of Chemistry 2012.
- Djernes, Katherine E.,Padilla, Melissa,Mettry, Magi,Young, Michael C.,Hooley, Richard J.
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supporting information
p. 11576 - 11578
(2013/01/15)
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- Activation of molecular oxygen by a metal-organic framework with open 2,2′-bipyridine for selective oxidation of saturated hydrocarbons
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A metal-organic framework with open 2,2′-bipyridine sites can efficiently activate molecular oxygen for selective oxidation of a variety of saturated hydrocarbons with unprecedented activities and selectivities.
- Long, Jilan,Wang, Liming,Gao, Xingfa,Bai, Cuihua,Jiang, Huanfeng,Li, Yingwei
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supporting information
p. 12109 - 12111
(2013/01/16)
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- Selective oxidation of alkanes with molecular oxygen and acetaldehyde in compressed (supercritical) carbon dioxide as reaction medium
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The oxidation of cycloalkanes or alkylarenes with molecular oxygen and acetaldehyde as sacrificial co-reductant occurs efficiently in compressed (supercritical) carbon dioxide (scCO2) under mild multiphase conditions. No catalyst is required and high-pressure ATR-FTIR online measurements show that a radical reaction pathway is heterogeneously initiated by the stainless steel of the reactor walls. For secondary carbon atoms, high ketone to alcohol ratios are observed (3.5-7.9), most probably due to fast consecutive oxidation of alcoholic intermediates. Since C - C scission reactions are detected only to a very small extent, tertiary carbon atoms are transformed into the corresponding alcohols with high selectivity. Detailed analysis of the product distributions and other mechanistic evidence suggest that acetaldehyde acts not only as the sacrificial oxygen acceptor, but also as an efficient H-atom donor for peroxo and oxo radicals and as a crucial reductant for hydroperoxo intermediates. In comparison to other inert gases such as compressed N, or Ar, the use of carbon dioxide was shown to increase the yields of alkane oxygenates under identical reaction conditions.
- Theyssen, Nils,Hou, Zhenshan,Leitner, Walter
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p. 3401 - 3409
(2008/09/19)
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- Selective oxidation of cyclooctane to cyclootanone with molecular oxygen in the presence of compressed carbon dioxide
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The oxidation of cyclooctane (1) to cyclooctanone (3) with molecular oxygen and acetaldehyde (2) as a co-reductant occurs efficiently in the presence of compressed CO2. Up to 20% yields of 3 are obtained under optimised multiphase conditions.
- Theyssen, Nils,Leitner, Walter
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p. 410 - 411
(2007/10/03)
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- Alkane oxidation with molecular oxygen using a new efficient catalytic system: N-hydroxyphthalimide (NHPI) combined with Co(acac)n (n = 2 or 3)
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A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)n (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)2 in acetic acid at 100°C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their α-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (kH/kD) in the oxidation of ethylbenzene and ethylbenzene-d10 with dioxygen using NHPI/Co(acac)2 was 3.8.
- Ishii, Yasutaka,Iwahama, Takahiro,Sakaguchi, Satoshi,Nakayama, Kouichi,Nishiyama, Yutaka
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p. 4520 - 4526
(2007/10/03)
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- Formation of Dicarbonyl Compounds in the Flash Vacuum Pyrolysis of Saturated Bicyclic Peroxides
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Under flash vacuum pyrolysis, dioxabicycloalkanes (n = 3,4, and 5) isomerise to keto-aldehydes, MeCOnCHO, whereas dioxabicycloalkanes (n = 2,3, and 4) fragment to give, by loss of hydrogen and ethylene, mixtures of cycloalkane-1,4-diones and dialdehydes, OHCnCHO.
- Bloodworth, A. J.,Baker, David S.,Eggelte, Henny J.
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p. 1034 - 1036
(2007/10/02)
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