504-01-8Relevant articles and documents
Selective hydrogenation of lignin-derived compounds under mild conditions
Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
, p. 3069 - 3073 (2020/06/17)
A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
A stable and practical nickel catalyst for the hydrogenolysis of C-O bonds
Cui, Xinjiang,Yuan, Hangkong,Junge, Kathrin,Topf, Christoph,Beller, Matthias,Shi, Feng
, p. 305 - 310 (2017/01/24)
The selective hydrogenolysis of C-O bonds constitutes a key step for the valorization of biomass including lignin fragments. Moreover, this defunctionalization process offers the possibility of producing interesting organic building blocks in a straightforward manner from oxygenated compounds. Herein, we demonstrate the reductive hydrogenolysis of a wide variety of ethers including diaryl, aryl-alkyl and aryl-benzyl derivatives catalyzed by a stable heterogeneous NiAlOx catalyst in the presence of a Lewis acid (LA). The special feature of this catalyst system is the formation of substituted cyclohexanols from the corresponding aryl ether.
Upgrading of aromatic compounds in bio-oil over ultrathin graphene encapsulated Ru nanoparticles
Shi, Juanjuan,Zhao, Mengsi,Wang, Yingyu,Fu, Jie,Lu, Xiuyang,Hou, Zhaoyin
supporting information, p. 5842 - 5848 (2016/05/24)
Fast pyrolysis of biomass for bio-oil production is a direct route to renewable liquid fuels, but raw bio-oil must be upgraded in order to remove easily polymerized compounds (such as phenols and furfurals). Herein, a synthesis strategy for graphene encapsulated Ru nanoparticles (NPs) on carbon sheets (denoted as Ru@G-CS) and their excellent performance for the upgrading of raw bio-oil were reported. Ru@G-CS composites were prepared via the direct pyrolysis of mixed glucose, melamine and RuCl3 at varied temperatures (500-800 °C). Characterization indicated that very fine Ru NPs (2.5 ± 1.0 nm) that were encapsulated within 1-2 layered N-doped graphene were fabricated on N-doped carbon sheets (CS) in Ru@G-CS-700 (pyrolysis at 700 °C). And the Ru@G-CS-700 composite was highly active and stable for hydrogenation of unstable components in bio-oil (31 samples including phenols, furfurals and aromatics) even in aqueous media under mild conditions. This work provides a new protocol to the utilization of biomass, especially for the upgrading of bio-oil.
Ruthenium Nanoparticles Stabilized in Cross-Linked Dendrimer Matrices: Hydrogenation of Phenols in Aqueous Media
Maximov, Anton,Zolotukhina, Anna,Murzin, Vadim,Karakhanov, Edward,Rosenberg, Edward
, p. 1197 - 1210 (2015/04/14)
Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975h-1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinoneacatechol. The maximum specific activity for resorcinol was a turnover frequency of 243150h-1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity.
Greener selective cycloalkane oxidations with hydrogen peroxide catalyzed by copper-5-(4-pyridyl)tetrazolate metal-organic frameworks
Martins, Luísa,Nasani, Rajendar,Saha, Manideepa,Mobin, Shaikh,Mukhopadhyay, Suman,Pombeiro, Armando
, p. 19203 - 19220 (2015/11/27)
Microwave assisted synthesis of the Cu(I) compound [Cu(μ4-4-ptz)]n [1, 4-ptz = 5-(4-pyridyl)tetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II) compounds [Cu3(μ3-4-ptz)4(μ2-N3)2(DMF)2]n·(DMF)2n (2) and [Cu(μ2-4-ptz)2(H2O)2]n (3) using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane) with aqueous hydrogen peroxide, under very mild conditions (at room temperature), without any added solvent or additive. The most efficient system (2/H2O2) showed, for the oxidation of cyclohexane, a turnover number (TON) of 396 (TOF of 40 h?1), with an overall product yield (cyclohexanol and cyclohexanone) of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1-3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.
Preparation, characterization and catalytic activity of MgO/SiO2 supported vanadium oxide based catalysts
Aboelfetoh, Eman Fahmy,Pietschnig, Rudolf
, p. 97 - 103 (2014/03/21)
Vanadium oxide-based catalyst obtained by grafting VOCl3 on Florisil (MgO:SiO2) with the molar ratio of 15:85 have been studied for the selective oxidation of cyclohexane in order to obtain cyclohexyl hydroperoxide, cyclohexanol and
Aqueous-phase hydrodeoxygenation of highly oxygenated aromatics on platinum
Yang, Jin,Williams, C. Luke,Ramasubramaniam, Ashwin,Dauenhauer, Paul J.
, p. 675 - 682 (2014/02/14)
Utilization of renewable sugars from biomass by a hybrid chemical process produces highly oxygenated aromatic compounds, such as phloroglucinol, which require catalytic reduction for desirable aromatic products. Aqueous phase hydrodeoxygenation of phloroglucinol on carbon-supported platinum produces resorcinol, phenol, cyclohexanol, cyclohexanone, and 1,3-cyclohexanediol by combinations of carbon-oxygen bond cleavage and carbon-carbon double bond hydrogenation. Carbon-carbon σ-bond cleavage was not observed. Hydrodeoxygenation was the primary reaction of phloroglucinol, leading to the production of resorcinol in the overall rate-limiting reaction, with an activation energy barrier of Ea = 117 kJ mol-1. Subsequent reactions of resorcinol produced 1,3-cyclohexanediol and phenol with similar energy barriers, Ea = 46 and Ea = 54 kJ mol-1, respectively. Further hydrogenation of phenol (Ea = 42 kJ mol -1) occurs through the intermediate, cyclohexanone, which is further reduced (Ea = 14 kJ mol-1) to the dominant product, cyclohexanol.
Photochemistry of 2-nitrobenzylidene acetals
Sebej, Peter,Solomek, Tomas,Hroudna, L'ubica,Brancova, Pavla,Klan, Petr
experimental part, p. 8647 - 8658 (2010/02/28)
(Figure Presented) Photolysis of dihydroxy compounds (diols) protected as 2-nitrobenzylidene acetals (ONBA) and subsequent acid- or base-catalyzed hydrolysis of the 2-nitrosobenzoic acid ester intermediates result in an efficient and high-yielding release of the substrates. We investigated the scope and limitations of ONBA photochemistry and expanded upon earlier described two-step procedures to show that the protected diols of many structural varieties can also be liberated in a one-pot procedure. In view of the fact that the acetals of nonsymmetrically substituted diols are converted into one of the corresponding 2-nitrosobenzoic acid ester isomers with moderate to high regioselectivity, the mechanism of their formation was studied using various experimental techniques. The experimental data were found to be in agreement with DFT-based quantum chemical calculations that showed the preferential cleavage occurs on the acetal C-O bond in the vicinity of more electron-withdrawing (or less electron-donating) groups. The study also revealed considerable complexity in the cleavage mechanism and that the structural variations in the substrate can significantly alter the reaction pathway. This deprotection strategy was found to be also applicable for 2-thioethanol when released from the corresponding monothioacetal in the presence of a reducing agent, such as ascorbic acid.
Raney ni-al alloy mediated hydrodehalogenation and aromatic ring hydrogenation of halogenated phenols in aqueous medium
Liu, Guo-Bin,Zhao, Hong-Yun,Zhang, Jie,Thiemannb, Thies
experimental part, p. 342 - 344 (2010/01/16)
Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a very powerful reducing agent and is highly effective for the reductive dehalogenation of polyhalogenated phenols and aromatic ring hydrogenation of phenols to the corresponding cyclohexanols.
Selective partial hydrogenation of hydroxy aromatic derivatives with palladium nanoparticles supported on hydrophilic carbon
Makowski, Philippe,Demir Cakan, Rezan,Antonietti, Markus,Goettmann, Frederic,Titirici, Maria-Magdalena
, p. 999 - 1001 (2008/09/21)
Selective hydrogenation of phenol to cyclohexanol in the aqueous phase was achieved using a new catalytic system based on palladium particles supported on hydrophilic carbon prepared by one-pot hydrothermal carbonisation. The Royal Society of Chemistry.
