5379-26-0Relevant academic research and scientific papers
Metallic Barium: A Versatile and Efficient Hydrogenation Catalyst
Stegner, Philipp,F?rber, Christian,Zenneck, Ulrich,Knüpfer, Christian,Eyselein, Jonathan,Wiesinger, Michael,Harder, Sjoerd
, p. 4252 - 4258 (2021)
Ba metal was activated by evaporation and cocondensation with heptane. This black powder is a highly active hydrogenation catalyst for the reduction of a variety of unactivated (non-conjugated) mono-, di- and tri-substituted alkenes, tetraphenylethylene, benzene, a number of polycyclic aromatic hydrocarbons, aldimines, ketimines and various pyridines. The performance of metallic Ba in hydrogenation catalysis tops that of the hitherto most active molecular group 2 metal catalysts. Depending on the substrate, two different catalytic cycles are proposed. A: a classical metal hydride cycle and B: the Ba metal cycle. The latter is proposed for substrates that are easily reduced by Ba0, that is, conjugated alkenes, alkynes, annulated rings, imines and pyridines. In addition, a mechanism in which Ba0 and BaH2 are both essential is discussed. DFT calculations on benzene hydrogenation with a simple model system (Ba/BaH2) confirm that the presence of metallic Ba has an accelerating effect.
Triphase hydrogenation reactions utilizing palladium-immobilized capillary column reactors and a demonstration of suitability for large scale synthesis
Kobayashi, Juta,Mori, Yuichiro,Kobayashi, Shu
, p. 1889 - 1892 (2005)
We have developed a practical and highly productive system for hydrogenation reactions utilizing capillary column reactors, which occupy less space than ordinary batch systems, are low cost and easy to handle, and show feasibility toward large-scale chemical synthesis. Palladium-containing micelles were immobilized onto the inner surface of the capillaries. Nine palladium-immobilized capillaries were assembled and connected to a T-shaped connector, and hydrogen and a substrate solution were fed to capillaries via the connector. Hydrogenation of 1-phenyl-1-cyclohexene (1) proceeded smoothly to give phenylcyclohexane in quantitative yield. The capillaries themselves occupy only ca. 0.4 mL and a high space-time yield has been achieved (124.3 mg/17 min/0.4 mL). In addition, leaching of palladium was not detected by ICP analysis after reactions.
An Effect of a Support Nature and Active Phase Morphology on Catalytic Properties of Ni-Containing Catalysts in Hydrogenation of Biphenyl
Chernova,Minayev,Martynenko, Ye. A.,Pimerzin, Al. A.,Yeremina, Yu. V.,Verevkin,Pimerzin
, p. 1701 - 1710 (2018)
Ni/Sup catalysts were prepared, where SBA-15, γ-Al2O3, SiO2 were used as supports (Sup). The synthesized catalysts were investigated by the methods of low-temperature nitrogen adsorption, temperatureprogrammed reduction (TPR), and high-resolution transmission electron microscopy. The catalytic properties of the prepared catalysts were tested in liquid phase hydrogenation of biphenyl under conditions of a flow installation at temperatures of 60–100°C, pressure of 4 MPa, volumetric feed rate of 4–10 h–1 and H2: feed ratio of 1500 nM. A 1 wt % solution of biphenyl in heptane, as a model mixture, was used. It has been established that the activity of nickel hydrogenation catalysts depends on the nickel content and the type of support. The activity of supported nickel catalysts decreases in the series Ni-12/SBA-15 > Ni-12/SiO2 >> Ni-12/Al2O3. The kinetic characteristics of the biphenyl hydrogenation reaction were determined: the rate constants and activation energy for the hydrogenation of the first and second aromatic rings of the substrate molecule.
Multinuclear iron-phenyl species in reactions of simple iron salts with PhMgBr: Identification of Fe4(μ-Ph)6(THF)4 as a key reactive species for cross-coupling catalysis
Carpenter, Stephanie H.,Baker, Tessa M.,Mu?oz, Salvador B.,Brennessel, William W.,Neidig, Michael L.
, p. 7931 - 7939 (2018)
The first direct syntheses, structural characterizations, and reactivity studies of iron-phenyl species formed upon reaction of Fe(acac)3 and PhMgBr in THF are presented. Reaction of Fe(acac)3 with 4 equiv. PhMgBr in THF leads to the formation of [FePh2(μ-Ph)]22- at -80 °C, which can be stabilized through the addition of N-methylpyrrolidone. Alternatively, at -30 °C this reaction leads to the formation of the tetranuclear iron-phenyl cluster, Fe4(μ-Ph)6(THF)4. Further synthetic studies demonstrate that analogous tetranuclear iron clusters can be formed with both 4-F-PhMgBr and p-tolylMgBr, illustrating the generality of this structural motif for reactions of simple ferric salts and aryl Grignard reagents in THF. Additional studies isolate and define key iron species involved in the synthetic pathway leading to the formation of the tetranuclear iron-aryl species. While reaction studies demonstrate that [FePh2(μ-Ph)]22- is unreactive towards electrophile, Fe4(μ-Ph)6(THF)4 is found to rapidly react with bromocyclohexane to selectively form phenylcyclohexane. Based on this reactivity, a new catalytic reaction protocol has been developed that enables efficient cross-couplings using Fe4(μ-Ph)6(THF)4, circumventing the current need for additives such as TMEDA or supporting ligands to achieve effective cross-coupling of PhMgBr and a secondary alkyl halide.
Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
supporting information, p. 5958 - 5963 (2021/08/18)
Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
Effect of pre-activation treatment temperature on hydrodesulfurization catalytic activity of CoMoS/KIT-6
Beltrán, Karen A.,Alvarez-Contreras, Lorena,Delgado, Anabel D.,Leyva-Porras, César C.,Aguilar-Elguezabal, Alfredo
, p. 106 - 115 (2019/11/26)
Mesoporous silica-supported cobalt–molybdenum hydrodesulfurization catalysts have been prepared by wetness impregnation, drying and a thermal pre-treatment of impregnated support before activation. Characterization of materials was made by nitrogen adsorption, thermogravimetric analysis, Raman spectroscopy, TEM and XPS. Catalytic activity was determined by hydrodesulfurization of dibenzothiophene (DBT). The results indicate that the thermal pre-treatment carried out at the lower temperature allows the formation of smaller and less stacked active phase structures, with a higher amount of CoMoS phase.
Novel Molybdenite-Based Nanopowder Catalysts for Hydrodesulfurization
Fedushchak,Uimin,Maikov,Akimov,Zhuravkov,Vosmerikov,Prosvirin,Velichkina,Stepanov,Kogan
, p. 794 - 805 (2021/07/14)
Abstract: Novel bulk single-component sulfide catalysts were prepared under theconditions of solid-phase dispersion of МoS2 molybdeniteat various mechanical treatment times and various amounts of polar and nonpolarliquid microadditives. The chemical degradation of the samples in the air wasfound to lead to the formation of surface sulfate anions that shieldcatalytically active Mo sites. Indirect correlations of the hydrodesulfurizationability of MoS2 powders with the concentration of sulfateanions on their surface, and with the aqueous pH in the powder suspensions,including the dielectric permittivity of the organic dopants, can serve asreference indicators of high catalytic activity in the model reaction ofdibenzothiophene hydrogenolysis. The study identified the most active sampleable to run for an extended time during multiple cycles without losing itscatalytic properties. Also, the paper discusses the dibenzothiophene conversionroutes, the product composition, the probable structure of active sites in thecatalysts, and the desulfurization degree of diesel fuel components. [Figure not available: see fulltext.]
Synergy effect of boron and cobalt in B2O3-SBA-15-(Co)Mo catalyst for efficient hydrodesulfurization of liquid fuels
Ganiyu, Saheed A.
, p. 3751 - 3768 (2021/05/11)
The contributory effect of surface acidity is significant to desulfurize heavy recalcitrant organosulfur compounds effectively. This research explores the synergistic effect of boron and cobalt in CoMoS supported on B2O3-SBA-15 for ultradeep hydrodesulfurization (HDS) of DBT and MDBT in the model and diesel fuel, respectively. The catalysts prepared consisting of SBA-15-(Co)Mo, representing (SM and SMC) and B2O3-SBA-15-(Co)Mo for BSM and BSMC, were fully characterized to gain insight into the structural activity concerning the nature of the fuel and the organosulfur compound employed. The incorporation of boron into the mesoporous framework of SBA-15 improves the surface characteristics, viz. surface acidity, support metal interaction and textural properties, necessary for efficient catalytic HDS reaction. The catalysts BSM and BSMC outperformed their analogous catalysts SM and SMC. The catalytic efficiency of BSMC is outstanding and capable of desulfurizing diesel fuel (1000 ppmw-S) containing a more complex matrix with a 90% conversion of methyldibenzothiophene (MDBT). BSMC possessed favorable and lower activation energy (Ea) of 77.11 kJ mol?1 than other catalysts and can be used as a commercial catalyst for ultradeep desulfurization of real fuel. Graphic abstract: [Figure not available: see fulltext.].
Indium Tribromide-Catalysed Transfer-Hydrogenation: Expanding the Scope of the Hydrogenation and of the Regiodivergent DH or HD Addition to Alkenes
Li, Luomo,Hilt, Gerhard
supporting information, p. 11221 - 11225 (2021/06/25)
The transfer-hydrogenation as well as the regioselective and regiodivergent addition of H?D from regiospecific deuterated dihydroaromatic compounds to a variety of 1,1-di- and trisubstituted alkenes was realised with InBr3 in dichloro(m)ethane. In comparison with the previously reported BF3?Et2O-catalysed process, electron-deficient aryl-substituents can be applied reliably and thereby several restrictions could be lifted, and new types of substrates could be transformed successfully in hydrodeuterogenation as well as deuterohydrogenation transfer-hydrogenation reactions.
Ligand-enabled and magnesium-activated hydrogenation with earth-abundant cobalt catalysts
Han, Bo,Jiao, Hongmei,Ma, Haojie,Wang, Jijiang,Zhang, Miaomiao,Zhang, Yuqi
, p. 39934 - 39939 (2021/12/31)
Replacing expensive noble metals like Pt, Pd, Ir, Ru, and Rh with inexpensive earth-abundant metals like cobalt (Co) is attracting wider research interest in catalysis. Cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. Herein, we describe a hydrogenation method for polycyclic aromatic hydrocarbons (PAHs) and olefins with a magnesium-activated earth-abundant Co catalyst. When diketimine was used as a ligand, simple and inexpensive metal salts of CoBr2in combination with magnesium showed high catalytic activity in the site-selective hydrogenation of challenging PAHs under mild conditions. Co-catalyzed hydrogenation enabled the reduction of two side aromatics of PAHs. A wide range of PAHs can be hydrogenated in a site-selective manner, which provides a cost-effective, clean, and selective strategy to prepare partially reduced polycyclic hydrocarbon motifs that are otherwise difficult to prepare by common methods. The use of well-defined diketimine-ligated Co complexes as precatalysts for selective hydrogenation of PAHs and olefins is also demonstrated.
