2979-24-0Relevant articles and documents
Microporous zirconia-silica mixed oxides made by sol-gel as catalysts for the liquid-phase oxidation of olefins with hydrogen peroxide
Palazzi, Chiara,Oliva, Liliana,Signoretto, Michela,Strukul, Giorgio
, p. 286 - 293 (2000)
Microporous zirconia-silica mixed oxides were prepared by sol-gel method and their reactivity in the oxidation of olefins with hydrogen peroxide was examined. The catalysts were characterized via BET methods, thermogravimetric analysis, XRD, UV-vis spectroscopy and TPD of ammonia. They had high surface areas, were amorphous and possessed only mild surface acidity. The reactivity order observed in the oxidation of olefins is a strong indication that the reaction proceeds through a heterolytic mechanism in which a nucleophilic olefin attacks a surface-electron-poor zirconium peroxo species. Although in all cases, the epoxide is likely involved as the primary reaction oxidation product. The acidity of the medium and/or support led to the opening of the oxirane ring. In the absence of solvent, the catalysts showed high selectivity (>99% glycol) at moderate temperature. In general, the activity and selectivity of the catalysts appear to be controlled by an appropriate polarity of the medium in which the reaction is carried out, by the polarity/acidity of the surface, and by the possibility to carry out the reaction at lower temperatures where the acidity effects of the hydrogen peroxide and silica matrix could be minimized.
Target-Architecture Engineering of a Novel Two-dimensional Metal-Organic Framework for High Catalytic Performance
Afshariazar, Farzaneh,Morsali, Ali
, p. 4239 - 4245 (2019)
A novel 2D-MOF, [Zn(L1)(oba)], an effective heterogeneous H-bond donor catalyst, based on carbohydrazide moiety (L1), was synthesized. Remarkable enhanced catalytic activity was achieved for methanolysis of epoxides by applying two effective strategies: (i) increasing the acidic strength of the H-bond donors and (ii) providing more accessible active sites within the framework.
Neighboring Methoxy Group Effect in Solvolysis Reactions of Cyclopentyl and Cyclohexyl p-Toluenesulfonates
Roberts, Donald D.
, p. 1857 - 1859 (1997)
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Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Manna, Kuntal,Newar, Rajashree,Rawat, Manhar Singh
supporting information, (2022/01/19)
The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
Role of Catalyst Support's Physicochemical Properties on Catalytic Transfer Hydrogenation over Palladium Catalysts
Batalha, Nuno,Fraga, Gabriel,Hasan, M. D.,Konarova, Muxina,Laycock, Bronwyn,Pratt, Steven,Santos, Mirella S.
, p. 5191 - 5202 (2021/10/29)
Catalytic transfer hydrogenation (CTH) is a promising reaction for valorisation of bio-based feedstocks via hydrogenation without needing to use H2. Unlike standard hydrogenation, CTH occurs via dehydrogenation (DHD) of a hydrogen donor (H-donor) and hydrogenation (HYD) of a substrate. Therefore, the “ideal” CTH catalyst must balance the catalysis of both reactions to maximize the hydrogen transfer between H-donor and substrate with minimal H2 loss to gas (high atom efficiency). Additionally, the H-donor must be highly stable to prevent secondary reactions with the substrate. Herein we study the impact of the catalyst's properties on CTH of guaiacol using bicyclohexyl, a liquid organic hydrogen carrier, as a H-donor. The reaction was promoted by palladium dispersed on three typical support materials (γ-Al2O3, MgO, and SiO2). The performance of these catalysts in the conversion of bicyclohexyl and guaiacol was evaluated, allowing to estimate the H-transfer efficiency, as well as the potential for recycling the spent H-donor (bicyclohexyl). The apparent activation energies for DHD of bicyclohexyl and HYD of guaiacol revealed that slow DHD combined with fast HYD, as is the case with Pd/MgO, favours hydrogen transfer efficiency and selectivity towards hydrogenated products. In addition, an investigation of the DHD of bicyclohexyl and HYD of guaiacol independently showed that the affinity between the organic molecules and the support significantly impacts CTH. Indeed, Pd/SiO2 was highly active for both reactions individually and almost inactive for CTH. Consequently, these findings highlight the importance of the interaction between solvent-substrate-support in designing catalysts for transfer hydrogenation.
