- Studies Concerning the Factors Affecting the Formation of Cyclohexanone Intermediates in the Catalytic Hydrogenation of Phenols. I. Hydrogenation of p-Cresol over Various Pd-C Catalysts
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The catalytic hydrogenation of p-cresol with commercial Pd on active carbon (Pd-C), water-washed Pd-C (Pd-C-N), acid-treated Pd-C (Pd-C-A), and base-treated Pd-C (Pd-C-B) has been kinetically studied in cyclohexane as a solvent under 0.15-8.0 MPa hydrogen pressure at 80 deg C.Under each reaction condition, the hydrogenation rate constants for the cresol and the ketone intermediate, k1+k3 and k2, respectively, the relative reactivity of the ketone to the cresol (K) and the ratio of the adsorption coefficient of the ketone to that of the cresol (b2/b1) were determined of the basis of a Langmuir-Hinshelwood model.Regardless of the difference in the nature of the catalysts, hydrogenations with these catalysts always gave high selectivities of 0.85-1.0 for the formation of the ketone intermediate, and small values of 0.014-0.62 for the relative reactivity (K).The small values of K over Pd-C and Pd-C-B were shown to be mostly due to the small values of k2/(k1+k3).In contrast, even smaller values of K over Pd-C-N and Pd-C-A were found due to a great difference in the strength of adsorption between the cresol and the ketone intermediate.In general, both the values of K and k2/(k1+k3) increase with increasing hydrogen pressure.All of the experimental results show that both the alkaline impurities associated with catalyst preparation and the hydrogen pressure are the most important factors affecting the formation of the ketone intermediate.
- Higashijima, Michio,Nishimura, Shigeo
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Read Online
- Synthesis method of 4-substituent cyclohexanone liquid crystal intermediate
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The invention discloses a synthesis method of a 4-substituent cyclohexanone liquid crystal intermediate, which comprises the following step: carrying out oxidation catalytic reaction on 4-substituent cyclohexanol under the action of trichloroisocyanide urea to obtain the 4-substituent cyclohexanone liquid crystal intermediate. The method is high in reaction selectivity, high in yield, environment-friendly, simple in post-treatment and suitable for industrial production.
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Paragraph 0044; 0046-0047
(2021/05/19)
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- Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
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Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.
- Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
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p. 4429 - 4438
(2021/07/12)
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- Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
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A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
- Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
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supporting information
p. 9925 - 9937
(2021/06/30)
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- CATALYTIC PROCESS
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A catalytic process for the deoxygenation of an organic substrate, such as a biomass or bio-oil, is described. The catalytic process is conducted in the presence of a gaseous mixture containing both hydrogen and nitrogen. The presence of nitrogen in the gaseous mixture gives rise inter-aliato increased catalytic activity and/or increased selectivity for aromatic reaction products.
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Paragraph 0224; 0244; 0248
(2021/12/03)
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- POLITAG-Pd(0) catalyzed continuous flow hydrogenation of lignin-derived phenolic compounds using sodium formate as a safe H-source
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Phenols are aromatic biobased compounds and as they are accessible from lignin depolymerization, they can be a useful platform chemicals to produce value-added products. Herein we report our recent investigations on the definition of an approach to the efficient continuous flow selective hydrogenation of phenols in water. Our protocol is based on the use of sodium formate as a clean and safe hydrogen source in combination with our newly defined heterogeneous POLITAG-Pd(0) catalytic system. POLITAG is a polymeric heterogeneous support decorated with pincer-type ionic ligands proven to be highly efficient for the stabilization of Pd(0) nanoparticles. The results obtained are remarkable in comparison with other protocols that employ sodium formate as H-source. Indeed, our investigation has been extended to a variety of differently substituted phenolic compounds that have been hydrogenated with excellent to good selectivity in continuous flow conditions. Durability of the catalyst has been also tested with a representative continuous processing of over 100 mmol that showed no loss in efficiency and minimal metal leaching.
- Campana, Filippo,Ferlin, Francesco,Silvetti, Matteo,Trombettoni, Valeria,Vaccaro, Luigi,Valentini, Federica
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- Highly Selective Hydrogenation of Phenols to Cyclohexanone Derivatives Using a Palladium@N-Doped Carbon/SiO2Catalyst
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A new palladium-based heterogeneous material was synthesized by means of immobilization of Pd(OAc)2/1,10-phenanthroline on commercially available SiO2and subsequent pyrolysis at 600 °C for 2 h in air, namely, a Pd@N-doped carbon/SiO2catalyst. The obtained catalyst was studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) techniques, and was effectively applied in the highly selective hydrogenation of phenols to give the corresponding cyclohexanone derivatives with 93-98% yields at 100 °C under 0.4 MPa H2in EtOH. It was demonstrated that introducing nitrogen could effectively promote the Pd dispersion and enhance the electronic interaction of Pd, both of which facilitate the improvement of the catalytic activity and selectivity. The likely reaction pathway was outlined to elucidate the selective hydrogenation mechanism according to experimental results.
- Sheng, Xueru,Wang, Chao,Wang, Wentao
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supporting information
p. 2425 - 2431
(2021/11/16)
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- Heterogeneous photocatalytic anaerobic oxidation of alcohols to ketones by Pt-mediated hole oxidation
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We report a platinum nanocluster/graphitic carbon nitride (Pt/g-C3N4) composite solid catalyst with a photocatalytic anaerobic oxidation function for highly active and selective transformation of alcohols to ketones. The desirable products were successfully obtained in good to excellent yields from various functionalized alcohols at room temperature, including unactivated alcohols. Mechanistic studies indicated that the reaction could proceed through a Pt-mediated hole oxidation initiating an α-alcohol radical intermediate followed by a two-electron oxidation pathway. The merit of this strategy offers a general approach towards green and sustainable organic synthetic chemistry.
- Sun, Danhui,Li, Peihe,Wang, Xia,Wang, Yingying,Wang, Jinghui,Wang, Yin,Lu, Ye,Duan, Limei,Sarina, Sarina,Zhu, Huaiyong,Liu, Jinghai
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supporting information
p. 11847 - 11850
(2020/10/13)
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- Improved performance of SiO2-supported Ni3Ga intermetallic compound for deoxygenation of phenolic compounds
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Ni/SiO2 and SiO2-supported Ni3Ga and Ni5Ga3 intermetallic compounds were prepared by the sol-gel method and evaluated for the hydrodeoxygenation of various phenolic compounds at 0.1 MPa. In the hydrodeoxygenation of anisole, Ni3Ga/SiO2 was more active for direct deoxygenation to benzene than the corresponding catalyst prepared by the impregnation method as well as Ni/SiO2. The anisole conversion and selectivity to benzene reached 95.1% and 92.5% on Ni3Ga/SiO2 at 300 °C and WHSV of 2 h?1, respectively. In the HDOs of cresols and guaiacol, Ni3Ga/SiO2 still more dominatingly facilitated the direct deoxygenation, while Ni/SiO2 significantly promoted the C-CH3 bond cleavage.
- Chen, Jixiang,Niu, Xiongxiong,Wang, Liwen
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- Catalytic Transfer Hydrogenation of Arenes and Heteroarenes
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Transfer hydrogenation reactions are of great interest to reduce diverse molecules under mild reaction conditions. To date, this type of reaction has only been successfully applied to alkenes, alkynes and polarized unsaturated compounds such as ketones, imines, pyridines, etc. The reduction of benzene derivatives by transfer hydrogenation has never been described, which is likely due to the high energy barrier required to dearomatize these compounds. In this context, we have developed a catalytic transfer hydrogenation reaction for the reduction of benzene derivatives and heteroarenes to form complex 3-dimensional scaffolds bearing various functional groups at room temperature without needing compressed hydrogen gas.
- Gelis, Coralie,Heusler, Arne,Nairoukh, Zackaria,Glorius, Frank
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supporting information
p. 14090 - 14094
(2020/10/19)
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- The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
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The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
- Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
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supporting information
p. 13695 - 13700
(2020/08/24)
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- Trans-Selective and Switchable Arene Hydrogenation of Phenol Derivatives
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A trans-selective arene hydrogenation of abundant phenol derivatives catalyzed by a commercially available heterogeneous palladium catalyst is reported. The described method tolerates a variety of functional groups and provides access to a broad scope of trans-configurated cyclohexanols as potential building blocks for life sciences and beyond in a one-step procedure. The transformation is strategically important because arene hydrogenation preferentially delivers the opposite cis-isomers. The diastereoselectivity of the phenol hydrogenation can be switched to the cis-isomers by employing rhodium-based catalysts. Moreover, a protocol for the chemoselective hydrogenation of phenols to cyclohexanones was developed.
- Bergander, Klaus,Glorius, Frank,Heusler, Arne,Wollenburg, Marco
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p. 11365 - 11370
(2020/11/24)
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- Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems
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Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i.e., H2O and alkanes), in multistep continuous-flow reactors in the presence of heterogeneous Pd catalysts. The high product selectivity and functional-group tolerance of this method allowed aryl amines with diverse functional groups to be selectively obtained in high yields over a continuous operation time of one week.
- Ichitsuka, Tomohiro,Kobayashi, Shū,Koumura, Nagatoshi,Sato, Kazuhiko,Takahashi, Ikko
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supporting information
p. 15891 - 15896
(2020/07/13)
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- Iterative Preparation of Platinum Nanoparticles in an Amphiphilic Polymer Matrix: Regulation of Catalytic Activity in Hydrogenation
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We demonstrate that iteration of the seeded preparation of platinum nanoparticles dispersed in an amphiphilic polystyrene-poly(ethylene glycol) resin (ARP-Pt) regulates their catalytic activity in the hydrogenation of aromatic compounds in water. The catalytic activity of the fifth generation of ARP-Pt [G5] prepared through four iterations of the seeded preparation was far superior to that of the initial ARP-Pt [G1] in the hydrogenation of aromatic compounds in water.
- Hamasaka, Go,Osako, Takao,Srisa, Jakkrit,Torii, Kaoru,Uozumi, Yasuhiro
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supporting information
p. 147 - 152
(2020/01/23)
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- Fine-Bubble-Slug-Flow Hydrogenation of Multiple Bonds and Phenols
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We describe a promising method for the continuous hydrogenation of alkenes or alkynes by using a newly developed fine-bubble generator. The fine-bubble-containing slug-flow system was up to 1.4 times more efficient than a conventional slug-flow method. When applied in the hydrogenation of phenols to the corresponding cyclohexanones, the fine bubble-slug-flow method suppressed over-reduction. As this method does not require the use of excess gas, it is expected to be widely applicable in improving the efficiency of gas-mediated flow reactions.
- Iio, Takuya,Nagai, Kohei,Kozuka, Tomoki,Sammi, Akhtar Mst,Sato, Kohei,Narumi, Tetsuo,Mase, Nobuyuki
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supporting information
p. 1919 - 1924
(2020/11/09)
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- Electrocatalytic Upgrading of Lignin-Derived Bio-Oil Based on Surface-Engineered PtNiB Nanostructure
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The development of robust electrocatalysts for electrocatalytic hydrogenation (ECH) of guaiacol and related lignin model monomers is necessary for the stabilization or upgrading of bio-oil. Additionally, the efficiency of biomass conversion to bio-oil products remains below the minimum requirements for its implementation at scale. Herein, a PtNiB/CMK-3 catalyst with pronounced ECH performance in the conversion of guaiacol and related model lignin monomers to bio-oil under optimally mild conditions, through a modulation strategy that modified the electronic structure of PtNi via boron alloying, is prepared. Notably, the optimized PtNiB/CMK-3 exhibited an inspiring high faradaic efficiency of 86.2%, which is significantly higher (13.7 times) than that of the PtNi/CMK-3 without B-doping (6.3%). Experimental results and theoretical calculations showed that the B-doping optimized the PtNiB alloy surface electron structure, simultaneously promoting substrate and intermediate adsorption and the ECH process. In addition, the uniform dispersion of PtNiB nanoparticles embedded within the mesoporous channels of CMK-3 ensures an enhanced utilization efficiency, leading to improvements in stability and bio-oil product generation. The lab-scale ECH experiment of guaiacol also certified the scale-up potential. This work opens a promising avenue to the rational design of advanced and highly efficient electrocatalysts for biomass upgrading.
- Zhou, Yulin,Gao, Yijing,Zhong, Xing,Jiang, Wenbin,Liang, Yulin,Niu, Pengfei,Li, Meichao,Zhuang, Guilin,Li, Xiaonian,Wang, Jianguo
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- A New Route to Cyclohexanone using H2CO3 as a Molecular Catalytic Ligand to Boost the Thorough Hydrogenation of Nitroarenes over Pd Nanocatalysts
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Carbon dioxide has been important in green chemistry, especially in catalytic and chemical engineering applications. While exploring CO2 to produce cyclohexanone for nylon or nylon 66 that is currently produced with low yields using harsh catalytic methods, we made the exciting discovery that carbonic acid, generated from dissolved CO2 in water, was utilized as molecular catalytic ligand to produce cyclohexanone via the hydrogenation of nitrobenzene in aqueous solution that uses Pd catalysts with a total yield higher than 90 %. Importantly, the gaseous nature of catalytic ligand H2CO3 profoundly simplifies post-catalysis cleanup unlike liquid or solid catalysts. This new green catalysis strategy demonstrated the universality for hydrogenation of aromatic compounds like aniline and N-methylaniline and could be broadly applicable in other catalytic field like artificial photosynthesis and electrocatalytic organic synthesis.
- Zhao, Tian-Jian,Zhang, Jun-Jun,Zhang, Bing,Liu, Yong-Xing,Lin, Yun-Xiao,Wang, Hong-Hui,Su, Hui,Li, Xin-Hao,Chen, Jie-Sheng
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p. 2837 - 2842
(2019/05/27)
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- Correlation of the catalytic performance with Nb2O5 surface properties in the hydrodeoxygenation of lignin model compound
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Production of aromatic hydrocarbons through lignin hydrodeoxygenation (HDO) is of significant importance. Previously, we found that Ru/Nb2O5 was an excellent catalyst for the conversion of lignin to arenes with relatively high selectivity (71%). Herein, we aim to clarify which properties of Nb2O5 influence the activity and selectivity. Four Ru/Nb2O5 catalysts with different Nb2O5 morphologies were used in the HDO of 4-methylphenol. Intensive studies show that layered Nb2O5 supported Ru has more Nb[dbnd]O groups (unsaturated NbOx sites) and highest Ru dispersion, which led to the highest activity and toluene selectivity, this was further confirmed by loading pre-synthesized Ru colloids in various Nb2O5. Finally, a Ru/Nb2O5 catalyst with more unsaturated Nb[dbnd]O groups was designed and it was found that even with enzymatic lignin as the feedstock, the selectivity to arenes can reach up to 94.8% with the yield of hydrocarbons of 99.6%. This study provides a promising strategy for catalyst design towards the selective production of aromatic hydrocarbons from lignin.
- Xin, Yu,Dong, Lin,Guo, Yong,Liu, Xiaohui,Hu, Yongfeng,Wang, Yanqin
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p. 202 - 212
(2019/06/18)
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- Hydrogenation of Phenol to Cyclohexanone over Bifunctional Pd/C-Heteropoly Acid Catalyst in the Liquid Phase
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Abstract: Cyclohexanone is an important intermediate in the manufacture of polyamides in chemical industry, but direct selective hydrogenation of phenol to cyclohexanone under mild conditions is a challenge. Hydrogenation of phenol to cyclohexanone has been investigated in the presence of the composite catalytic system of Pd/C-heteropoly acid. 100% conversion of phenol and 93.6% selectivity of cyclohexanone were achieved within 3?h under 80?°C and 1.0?MPa hydrogen pressure. It has been found that a synergetic effect of Pd/C and heteropoly acid enhanced the catalytic performance of the composite catalytic system which suppressed the hydrogenation of cyclohexanone to cyclohexanol. Graphic Abstract: [Figure not available: see fulltext.].
- Liu, Shiwei,Han, Jing,Wu, Qiong,Bian, Bing,Li, Lu,Yu, Shitao,Song, Jie,Zhang, Cong,Ragauskas, Arthur J.
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p. 2383 - 2389
(2019/06/19)
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- Ammonium Tungstate as an Effective Catalyst for Selective Oxidation of Alcohols to Aldehydes or Ketones with Hydrogen Peroxide under Water - A Synergy of Graphene Oxide
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Ammonium tungstate was found to be a facile and efficient catalyst for selective oxidation of alcohols to the corresponding carbonyl compounds with hydrogen peroxide as oxidant. Heterogeneous graphene oxide as acid effectively intensified the transformations and resulted in excellent yields. The use of water as solvent rendered the reactions promising both economically and environmentally.
- Fu, Huihui,Hu, Chuanfeng,Huang, Zhida,Zhou, Jianhao,Peng, Xinhua
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supporting information
p. 447 - 451
(2017/11/27)
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- Mechanistic Aspects of Hydrodeoxygenation of p-Methylguaiacol over Rh/Silica and Pt/Silica
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The mechanism of p-methylguaiacol (PMG) hydrodeoxygenation (HDO) has been examined over two Rh/silica catalysts and a Pt/silica catalyst at 300 °C and 4 barg hydrogen. Sequential conversion of PMG to 4-methylcatechol is followed by m- and p-cresol formation and finally toluene production, although direct conversion of PMG to p-cresol is favored over a commercial Rh/silica catalyst. Dehydroxylation and hydrogenation are shown to occur over metal functions, while demethylation and demethoxylation are favored over the fumed silica support. A mechanistic pathway for HDO of PMG is proposed.
- Bouxin, Florent P.,Zhang, Xingguang,Kings, Iain N.,Lee, Adam F.,Simmons, Mark J. H.,Wilson, Karen,Jackson, S. David
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p. 1586 - 1589
(2018/09/25)
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- Mild and Regioselective Hydroxylation of Methyl Group in Neocuproine: Approach to an N,O-Ligated Cu6 Cage Phenylsilsesquioxane
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The self-Assembly synthesis of Cu(II)-silsesquioxane involving 2,9-dimethyl-1,10-phenanthroline (neocuproine) as an additional N ligand at copper atoms was performed. The reaction revealed an unprecedented aerobic hydroxylation of only one of the two methyl groups in neocuproine to afford the corresponding geminal diol. The produced derivative of oxidized neocuproine acts as a two-centered N,O ligand in the assembly of the hexacopper cage product [Cu6(Ph5Si5O10)2·(C14H11N2O2)2] (1), coordinating two of the six copper centers in the product. Two siloxanolate ligands [PhSi(O)O]5 in the cis configuration coordinate to the rest of the copper(II) ions. Compound 1 is a highly efficient homogeneous precatalyst in the oxidation of alkanes and alcohols with peroxides.
- Bilyachenko, Alexey N.,Levitsky, Mikhail M.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Shubina, Elena S.,Shul'Pin, Georgiy B.
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supporting information
p. 168 - 171
(2018/02/06)
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- Selective hydrogenation of phenol to cyclohexanone by SiO2-supported rhodium nanoparticles under mild conditions
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A silica-supported rhodium catalyst for the selective hydrogenation of phenol to cyclohexanone under mild conditions has been developed. As the Rh concentration on the catalyst increased from 0.5 to 15 wt%, the conversion (at phenol/Rh mole ratio 100/1) dropped whereas the initial selectivity to cyclohexanone increased. The direct hydrogenation to cyclohexanol occurred in parallel with partial hydrogenation to cyclohexanone. The negative correlation between selectivity and Rh dispersion suggests that direct hydrogenation occurs at low coordination sites whereas dissociation of phenol to phenoxy followed by hydrogenation to cyclohexanone takes place at higher coordinated terrace sites. DFT calculations revealed that the activation barrier for O–H bond cleavage is lower for phenol adsorbed on a Rh(1 1 1) flat surface than on small particles. By blocking the low coordination edge and step sites through grafting with (3-mercaptopropyl)trimethoxysilane, the cyclohexanone selectivity was improved from 82 to 93% at 100% conversion. The catalyst is active at room temperature and 1 atm H2 pressure and can be easily activated by in-situ reduction.
- Zhang, Hongwei,Han, Aijuan,Okumura, Kazu,Zhong, Lixiang,Li, Shuzhou,Jaenicke, Stephan,Chuah, Gaik-Khuan
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p. 354 - 365
(2018/06/26)
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- Synthesis of N-Doped Mesoporous Carbon Nanorods through Nano-Confined Reaction: High-Performance Catalyst Support for Hydrogenation of Phenol Derivatives
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Traditional hard-template methods for the preparation of mesoporous carbon structures have been well developed, but there are difficulties associated with complete filling of the organic precursors in ordered mesochannels and exact replication of the templates. Herein, mesoporous carbon nanorods (meso-CNRs) were synthesized through thermal condensation of furfuryl alcohol followed by the nano-confined decomposition of polyfurfuryl alcohol in silica nanotubes (SiO2 NTs) with porous shells. Limited and slow release of gaseous water through the porous shells and finite polyfurfuryl precursor inside silica nanotubes are responsible for the formation of the mesoporous structures. Nitrogen can be doped into the meso-CNRs by adding guanidine hydrochloride to the precursors. The nitrogen dopant not only stabilizes the ultrasmall and active Pd nanocatalyst in the meso-CNRs but also increases the electron density of Pd and accelerates the dissociation of H2, both of which increase the catalytic activity of the Pd catalyst in hydrogenation reactions.
- Liu, Xueteng,Pang, Fei,Ge, Jianping
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p. 822 - 829
(2018/03/07)
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- Ductile Pd-Catalysed Hydrodearomatization of Phenol-Containing Bio-Oils Into Either Ketones or Alcohols using PMHS and H2O as Hydrogen Source
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A series of phenolic bio-oil components were selectively hydrodearomatized by palladium on carbon into the corresponding ketones or alcohols in excellent yields using polymethylhydrosiloxane and water as reducing agent. The selectivity of the reaction was governed by the water concentration where selectivity to alcohol was favoured at higher water concentrations. As phenolic bio-oil examples cardanol and beech wood tar creosote were studied as substrate to the developed reaction conditions. Cardanol was hydrodearomatized into 3-pentadecylcyclohexanone in excellent yield. From beech wood tar creosote, a mixture of cyclohexanols was produced. No hydrodeoxygenation occurred, suggesting the applicability of the reported method for the production of ketone-alcohol oil from biomass. (Figure presented.).
- Di Francesco, Davide,Subbotina, Elena,Rautiainen, Sari,Samec, Joseph S. M.
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supporting information
p. 3924 - 3929
(2018/09/14)
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- Aerobic oxidation of secondary alcohols in water with ABNO/tert-butyl nitrite/KPF6catalytic system
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A green and efficient transition-metal free ABNO/tert-butyl nitrite/KPF6-catalyzed aerobic oxidation of secondary alcohols in water has been achieved. Under the optimal reaction conditions, a number of secondary aliphatic alcohols and secondary benzylic alcohols can be converted to their corresponding ketones in excellent yields (up to 99%).
- Ma, Jiaqi,Hong, Chao,Wan, Yan,Li, Meichao,Hu, Xinquan,Mo, Weimin,Hu, Baoxiang,Sun, Nan,Jin, Liqun,Shen, Zhenlu
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p. 652 - 657
(2017/01/25)
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- Synthesis and characterization of some new half-sandwich ruthenium(II) complexes with bidentate N,N′-ligands and their application in alcohol oxidation
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A series of eight new (η6-arene)ruthenium(II) complexes were prepared by the reaction of pyridyl-imine ligands and the ruthenium(II) precursors of the general formula [(η6-arene)Ru(μ-Cl)Cl]2, where arene = p-cymene (1) and C6H6(2), to form the complexes [(η6-arene)RuCl(C5H4N-2-CH[dbnd]N-Ar)]PF6(where Ar = 2,4,6-trimethylphenyl (a), 2,4-dimethylphenyl (b), 2-methoxyphenyl (c), 2,6-diisopropylphenyl (d)).These complexes were characterized using 1H NMR, 13C NMR, 31P NMR, IR, UV–Vis, HRMS, and TGA. The molecular structures for the complexes 1a,1d, 2a and 2d were determined by single crystal crystallography, revealing a pseudo-octahedral piano stool geometry. In this arrangement, the ruthenium metal is coordinated to the arene ligand at the apex of the stool with one chloride and the N,N-ligand as the base. These complexes were applied as catalysts in the oxidation of cyclic, aliphatic and aromatic alcohols with NaIO4as oxidant and the complexes showed good conversions and yields to the corresponding carbonyl products.
- Gichumbi, Joel M.,Friedrich, Holger B.,Omondi, Bernard
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- Construction of Distant Stereocenters by Enantioselective Desymmetrizing Carbonyl-Ene Reaction
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An efficient desymmetrizing carbonyl-ene reaction of 1-substituted 4-methylenecyclohexanes with glyoxal derivatives was thus executed by a chiral N,N′-dioxide/NiII catalyst, providing facile access to cyclohexene derivatives bearing two remote 1,6-related stereocenters. This distal stereocontrol methodology originates from the efficient interaction between the catalyst with enophiles, discrimination of the two chair conformations of olefinic components, and the intrinsic six-membered transition-state structure of ene process.
- Luo, Weiwei,Lin, Lili,Zhang, Yu,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 3374 - 3377
(2017/07/15)
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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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- A Ni-Mg-Al layered triple hydroxide-supported Pd catalyst for heterogeneous acceptorless dehydrogenative aromatization
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In the presence of a Ni-Mg-Al layered triple hydroxide-supported Pd catalyst, the acceptorless dehydrogenative aromatization of a wide range of cyclohexanols/cyclohexanones and cyclohexylamines efficiently proceeded to give the corresponding phenols and anilines, respectively, in moderate to high yields with the liberation of molecular hydrogen.
- Jin, Xiongjie,Taniguchi, Kento,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
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supporting information
p. 5267 - 5270
(2017/07/10)
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- Deactivation study of the hydrodeoxygenation of p-methylguaiacol over silica supported rhodium and platinum catalysts
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Hydrodeoxygenation of para-methylguaiacol using silica supported Rh or Pt catalysts was investigated using a fixed-bed reactor at 300?°C, under 4 barg hydrogen and a WHSV of 2.5?h?1. The activity, selectivity and deactivation of the catalysts were examined in relation to time on stream. Three catalysts were tested: 2.5% Rh/silica supplied by Johnson Matthey (JM), 2.5% Rh/silica and 1.55% Pt/silica both prepared in-house. The Rh/silica (JM) showed the best stability with steady-state reached after 6?h on stream and a constant activity over 3?days of reaction. In contrast the other two catalysts did not reach steady state within the timeframe of the tests, with continuous deactivation over the time on stream. Nevertheless higher coking was observed on the Rh/silica (JM) catalyst, while all three catalysts showed evidence of sintering. The Pt catalyst (A) showed higher selectivity for the production of 4-methylcatechol while the Rh catalysts were more selective toward the cresols. In all cases, complete hydrodeoxygenation of the methylguaiacol to methylcyclohexane was not observed.
- Bouxin,Zhang,Kings,Lee,Simmons,Wilson,Jackson
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- A Pd/Monolayer Titanate Nanosheet with Surface Synergetic Effects for Precise Synthesis of Cyclohexanones
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A catalyst composed of monolayer nonstoichiometric titanate nanosheets (denoted as TN) and Pd clusters is constructed for precise synthesis of cyclohexanone from phenol hydrogenation with high conversion (>99%) and selectivity (>99%) in aqueous media under light irradiation. Experimental and DFT calculation results reveal that the surface exposed acid and basic sites on TN could interact with phenol molecules in a nonplanar fashion via a hexahydroxy hydrogen-bonding ring to form a surface coordination species. This greatly facilitates the adsorption and activation of phenol molecules and suppresses the further hydrogenation of cyclohexanone. Moreover, the surface Pd clusters serve as the active sites for the adsorption and dissociation of hydrogen molecules to provide active H atoms. The synergistic effect of the surface coordination species, TN and Pd clusters remarkably facilitate the high yield of cyclohexanone in photocatalysis. Finally, the possible thermo/photocatalytic mechanisms on Pd/TN are proposed. This work not only highlights the great potential for monolayer nonstoichiometric composition nanosheets in the construction of catalysts for precise organic synthesis but also provides insight into the inherent catalytic behavior at a molecular level.
- Song, Yujie,Wang, Hao,Gao, Xiaomei,Feng, Yingxin,Liang, Shijing,Bi, Jinhong,Lin, Sen,Fu, Xianzhi,Wu, Ling
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p. 8664 - 8674
(2017/12/08)
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- NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates
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New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(η3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4-trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1-(pyridin-2-yl)propan-2-one provided the β-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.
- Martinez-Espinar, Francisco,Blondeau, Pascal,Nolis, Pau,Chaudret, Bruno,Claver, Carmen,Castillón, Sergio,Godard, Cyril
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p. 113 - 127
(2017/09/08)
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- A biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound (by machine translation)
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The invention relates to a biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound. It in order to load the noble metal palladium titanium dioxide as catalyst, biomass phenolic compound by catalytic hydrogenation synthesis of cyclohexyl alcohol compound, the obtained cyclohexyl alcohol compound can be used as fuel additives or pharmaceutical chemical intermediate, improving the utilization rate of renewable sources of energy, to relieve the energy crisis and the increasing importance attached to the problem of environmental pollution, its catalyst has simple preparation process, green environmental protection, does not pollute the environment, suitable for popularization and application. (by machine translation)
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Paragraph 0028; 0033
(2017/09/26)
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- Strongly coupled Mn3O4-porous organic polymer hybrid: A robust, durable and potential nanocatalyst for alcohol oxidation reactions
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Herein we describe a novel strategy for noble-metal-free Mn3O4@POP (porous organic polymer) hybrid synthesis by encapsulation of Mn3O4-NP in the interior cavity of a porous organic polymer which exhibited enhanced catalytic activity and stability for oxidation of diverse activated and nonactivated alcohols relative to the conventional catalysts to demonstrate the benefits of such a nanoarchitecture in heterogeneous nanocatalysis. The use of a non precious catalyst, tremendous recyclability (upto 15 catalytic runs) and exceptional stability make our system innovative in nature, addressing all the profound challenges in the noble-metal-free heterogeneous catalysts development community.
- Dhanalaxmi, Karnekanti,Singuru, Ramana,Kundu, Sudipta K.,Reddy, Benjaram Mahipal,Bhaumik, Asim,Mondal, John
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p. 36728 - 36735
(2016/05/24)
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- Au-Pd alloy nanoparticles supported on layered double hydroxide for heterogeneously catalyzed aerobic oxidative dehydrogenation of cyclohexanols and cyclohexanones to phenols
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Phenol, an important industrial chemical, is widely produced using the well-developed cumene process. However, demand for the development of a novel alternative method for synthesizing phenol from benzene has been increasing. Herein, we report a novel system for the synthesis of phenols through aerobic oxidative dehydrogenation of cyclohexanols and cyclohexanones, including ketone-alcohol (KA) oil, catalyzed by Mg-Al-layered double hydroxide (LDH)-supported Au-Pd alloy nanoparticles (Au-Pd/LDH). Alloying of Au and Pd and basicity of LDH are key factors in achieving the present transformation. Although monometallic Au/LDH, Pd/LDH, and their physical mixture showed almost no catalytic activity, Au-Pd/LDH exhibited markedly high catalytic activity for the dehydrogenative phenol production. Mechanistic studies showed that β-H elimination from Pd-enolate species is accelerated by Au species, likely via electronic ligand effects. Moreover, the effect of supports was critical; despite the high catalytic performance of Au-Pd/LDH, Au-Pd bimetallic nanoparticles supported on Al2O3, TiO2, MgO, and CeO2 were ineffective. Thus, the basicity of LDH plays a deterministic role in the present dehydrogenation possibly through its assistance in the deprotonation steps. The synthetic scope of the Au-Pd/LDH-catalyzed system was very broad; various substituted cyclohexanols and cyclohexanones were efficiently converted into the corresponding phenols, and N-substituted anilines were synthesized from cyclohexanones and amines. In addition, the observed catalysis was truly heterogeneous, and Au-Pd/LDH could be reused without substantial loss of its high performance. The present transformation is scalable, utilizes O2 in air as the terminal oxidant, and generates water as the only by-product, highlighting the potential practical utility and environmentally benign nature of the present transformation. Dehydrogenative aromatization of cyclohexanols proceeds through (1) oxidation of cyclohexanols to cyclohexanones; (2) dehydrogenation of cyclohexanones to cyclohexenones; and (3) disproportionation of cyclohexenones to afford the desired phenols. In the present Au-Pd/LDH-catalyzed transformation, the oxidation of the Pd-H species is included in the rate-determining step.
- Jin, Xiongjie,Taniguchi, Kento,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 5371 - 5383
(2016/07/29)
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- Novel cage-like hexanuclear nickel(II) silsesquioxane. Synthesis, structure, and catalytic activity in oxidations with peroxides
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New hexanuclear nickel(II) silsesquioxane [(PhSiO1.5)12(NiO)6(NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO1,5)12(NiO)6(NaCl)(C4H8O2)13(PhCN)2(H2O)2 and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers.
- Bilyachenko, Alexey N.,Yalymov, Alexey I.,Shul'pina, Lidia S.,Mandelli, Dalmo,Korlyukov, Alexander A.,Vologzhanina, Anna V.,Es'kova, Marina A.,Shubina, Elena S.,Levitsky, Mikhail M.,Shul'pin, Georgiy B.
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- Pd/TiN nanocomposite catalysts for selective hydrogenation of phenol and its derivatives
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Pd/TiN nanocomposite catalysts were fabricated for one-step selective hydrogenation of phenol to cyclohexanone successfully. High conversion of phenol (99%) and selectivity of cyclohexanone (98%) were obtained at 30?°C and 0.2?MPa H2for 12?h in the mixed solvents of H2O and CH2Cl2. The Pd nanoparticles were stable in the reaction, and no aggregation was detected after four successive runs. The catalytic activity and selectivity depended on slightly the Pd particle sizes. The generality of the catalysts for this reaction was demonstrated by the selective hydrogenation of phenol derivatives, which showed that the catalyst was selective for the formation of cyclohexanone.
- Li, Hai-Feng,Zhang, Qin-Sheng,Pang, Zeng-Bo,Tian, Mi,Gao, Ping,Wang, Lai-Lai
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p. 1500 - 1504
(2016/09/23)
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- Preparation of hydrophobic reduced graphene oxide supported Ni-B-P-O and Co-B-P-O catalysts and their high hydrodeoxygenation activities
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Hydrophobic reduced graphene oxide supported Ni-B-P-O and Co-B-P-O catalysts were synthesized by a chemical reduction method and these dispersed relatively well in a non-polar solvent, prevented contact with water, and consequently protected the active phases and exhibited high catalytic activity in the liquid-phase p-cresol hydrodeoxygenation reaction: both the conversion and deoxygenation degree were higher than 99% at 225 °C for 1 h.
- Wang, Weiyan,Liu, Pengli,Wu, Kui,Tan, Song,Li, Wensong,Yang, Yunquan
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p. 984 - 988
(2016/02/27)
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- A simple procedure for the oxidation of alcohols using [bis(acetoxy)iodo]benzene and a catalytic amount of bromide ions in ethyl acetate
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Abstract Primary and secondary benzylic alcohols and secondary aliphatic alcohols were oxidized to the corresponding aldehydes and ketones by using [bis(acetoxy)iodo]benzene (BAIB) and a catalytic amount of bromide ions, from tetrabutylammonium bromide or KBr, in ethyl acetate. The catalytic role of the bromide ions was also highlighted in the oxidation of primary aliphatic alcohols and secondary allylic alcohols carried out in the presence of 1 mol% TEMPO.
- Salvo, Anna Maria Pia,Campisciano, Vincenzo,Beejapur, Hazi Ahmad,Giacalone, Francesco,Gruttadauria, Michelangelo
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p. 1179 - 1184
(2015/06/02)
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- Nanocomposite shuttle-supported palladium nanoparticles as a PH-triggered phase transfer catalyst for the aerobic oxidation of alcohols
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Abstract We synthesize a novel mesoporous nanocomposite shuttle. It can reversibly transfer between the organic and water phase in response to pH. It was used as the precursor to load palladium nanoparticles for the aerobic oxidation of alcohols. The whole oxidation process with the catalyst is highly efficient and chemo-selective. The nanocomposite shuttle can take Pd nanoparticles to an organic phase for catalyzing, and then come back to the aqueous phase, thus benefiting the separation and recycling of the catalysts. The catalyst is stable and can be reused for at least five runs. The catalyst we discovered not only makes the whole reaction homogeneous, but can also can be separated by decanting.
- Zhu, Yaoqin,Xu, Jia,Lu, Ming
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p. 1213 - 1219
(2015/06/02)
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- Copper nanoparticles on dichromium trioxide: A highly efficient catalyst from copper chromium hydrotalcite for oxidant-free dehydrogenation of alcohols
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Stable copper(0) nanoparticles supported on chromium (Cu(0)/Cr2O3) are prepared from the composite precursor copper chromium hydrotalcite. The resulting Cu(0)/Cr2O3 catalyst is first used in the selective dehydrogenation of alcohols to aldehydes. More impressively, these dehydrogenations are performed without oxidants and yields of products are high. The stability of Cu(0)/Cr2O3 is also assessed by studying its recoverability and reusability for up to five cycles.
- Zhu, Yaoqin,Shen, Mengnan,Xia, Yonggen,Lu, Ming
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p. 152 - 156
(2015/03/30)
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- Alkane oxidation with peroxides catalyzed by cage-like copper(II) silsesquioxanes
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Isomeric cage-like tetracopper(II) silsesquioxane complexes [(PhSiO1.5)12(CuO)4(NaO0.5)4] (1a), [(PhSiO1.5)6(CuO)4(NaO0.5)4(PhSiO1.5)6] (1b) and binuclear complex [(PhSiO1.5)10(CuO)2(NaO0.5)2] (2) have been studied by various methods. These compounds can be considered as models of some multinuclear copper-containing enzymes. Compounds 1a and 2 are good pre-catalysts for the alkane oxygenation with hydrogen peroxide in air in an acetonitrile solution. Thus, the 1a-catalyzed reaction with cyclohexane at 60°C gave mainly cyclohexyl hydroperoxide in 17% yield (turnover number, TON, was 190 after 230 min and initial turnover frequency, TOF, was 100 h-1). The alkyl hydroperoxide partly decomposes in the course of the reaction to afford the corresponding ketone and alcohol. The effective activation energy for the cyclohexane oxygenation catalyzed by compounds 1a and 2 is 16 ± 2 and 17 ± 2 kcal mol-1, respectively. Selectivity parameters measured in the oxidation of linear and branched alkanes and the kinetic analysis revealed that the oxidizing species in the reaction is the hydroxyl radical. The analysis of the dependence of the initial reaction rate on the initial concentration of cyclohexane led to a conclusion that hydroxyl radicals attack the cyclohexane molecules in proximity to the copper reaction centers. The oxidations of saturated hydrocarbons with tert-butylhydroperoxide (TBHP) catalyzed by complexes 1a and 2 exhibit unusual selectivity parameters which are due to the steric hindrance created by bulky silsesquioxane ligands surrounding copper reactive centers. Thus, the methylene groups in n-octane have different reactivities: the regioselectivity parameter for the oxidation with TBHP catalyzed by 1a is 1:10.5:8:7. Furthermore, in the oxidation of methylcyclohexane the position 2 relative to the methyl group of this substrate is noticeably less reactive than the corresponding positions 3 and 4. Finally, the oxidation of trans-1,2-dimethylcyclohexane with TBHP catalyzed by complexes 1a and 2 proceeds stereoselectively with the inversion of configuration. The 1a-catalyzed reaction of cyclohexane with H216O2 in an atmosphere of 18O2 gives cyclohexyl hydroperoxide containing up to 50% of 18O. The small amount of cyclohexanone, produced along with cyclohexyl hydroperoxide, is 18O-free and is generated apparently via a mechanism which does not include hydroxyl radicals and incorporation of molecular oxygen from the atmosphere.
- Vinogradov, Mikhail M.,Kozlov, Yuriy N.,Bilyachenko, Alexey N.,Nesterov, Dmytro S.,Shul'pina, Lidia S.,Zubavichus, Yan V.,Pombeiro, Armando J. L.,Levitsky, Mikhail M.,Yalymov, Alexey I.,Shul'pin, Georgiy B.
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supporting information
p. 187 - 199
(2015/02/19)
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- Selective hydrogenation of phenol to cyclohexanone in water over PD@N-doped carbon derived from ionic-liquid precursors
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In this report, a kind of mesoporous N-doped carbon (CN-x) derived from N-containing ionic-liquid (IL) precursors were synthesized, and Pd@CN-x prepared by a simple ultrasound-assisted method showed higher catalytic activity for the selective hydrogenation of phenol and its derivatives under mild reaction conditions in water than commercial Pd@C and other common Pd heterogeneous catalysts. The catalytic activities of Pd@CN-x derived from different ILs were different, and further study into the influencing factors, including physical properties, N species of CN-x, and Pd status of Pd@CN-x, were performed. Being picky: N-Doped carbon (CN-x) derived from N-containing ionic-liquid precursors are used as Pd nanoparticle supports for the selective hydrogenation of phenol to cyclohexanone with high activity and selectivity under mild reaction conditions. The activities of the Pd@CN-x catalysts derived from a variety of ionic liquids are different, and studies on the physical properties, Pd status, and N species of the catalysts are performed.
- Xu, Xuan,Li, Haoran,Wang, Yong
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p. 3328 - 3332
(2015/04/16)
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- Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
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Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
- Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
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supporting information
p. 9250 - 9253
(2015/08/11)
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- Selective Hydrogenation of Phenol to Cyclohexanone over Pd-HAP Catalyst in Aqueous Media
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The production of pure cyclohexanone under mild conditions over catalysts with high reactivity, selectivity, compatibility, stability, and low cost is still a great challenge. Here we report a hydroxyapatite-bound palladium catalyst (Pd-HAP) to demonstrate its excellent performance on phenol hydrogenation to cyclohexanone. Based on catalyst characterization, the Pd nanoclusters (≈0.9 nm) are highly dispersed and bound to phosphate in HAP. Only basic active sites on HAP surface are detected. At 25°C and ambient H2 pressure in water, phenol can be 100% converted into cyclohexanone with 100% selectivity. This system shows a universal applicability to temperature, pH, solvent, low H2 purity, and pressure. The catalyst reveals high stability to be recycled without deactivation or morphology change; and Pd nano-clusters barely aggregate even at 400°C. During the reaction, HAP adsorbs phenol, and Pd nanoclusters activate and spillover H2. The mechanism is also investigated, proposed, and verified.
- Xu, Guangyue,Guo, Jianhua,Zhang, Ying,Fu, Yao,Chen, Jinzhu,Ma, Longlong,Guo, Qingxiang
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p. 2485 - 2492
(2015/08/24)
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- Efficient room-temperature aqueous-phase hydrogenation of phenol to cyclohexanone catalyzed by Pd nanoparticles supported on mesoporous MMT-1 silica with unevenly distributed functionalities
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Efficient and selective aqueous-phase hydrogenation of phenol by a novel Pd catalyst supported on dually and selectively functionalized mesoporous MMT-1 silica nanoparticles has been developed. The catalyst features small (~1.1 nm) Pd nanoparticles surrounded by unevenly distributed nitrogen- or heteroatom-free organic groups in the helical mesopores and the presence of non-hydrogen-bonded isolated silanol groups on the mesopore surface. The catalyst exhibited superior conversion of phenol and high selectivity of cyclohexanone at room temperature under atmospheric pressure of hydrogen and remained highly active after ten catalytic runs. The catalyst was active for the aqueous-phase hydrogenation of a variety of mono- and dihydroxylated aromatic compounds. The green protocol with the designed catalyst would be practical for the hydrogenation of phenol and other derivatives.
- Lin, Chi-Jui,Huang, Shao-Hsien,Lai, Nien-Chu,Yang, Chia-Min
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p. 4121 - 4129
(2015/11/11)
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- Synthesis of Ni-P-B amorphous nanoparticles with uniform size as a potential hydrodeoxygenation catalyst
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An Ni-P-B amorphous nano-catalyst was synthesized using a facile chemical reduction method. The amorphous degree was enhanced and the transferred electron decreased with an increase of P content in Ni-P-B. In the hydrodeoxygenation (HDO) of p-cresol, the conversion using Ni-P-B was high up to 98.9% with a selectivity of 6.5% for toluene and a deoxygenation degree of 96.8% at 498 K.
- Wang, Weiyan,Liu, Pengli,Wu, Kui,Zhang, Kun,Li, Lu,Qiao, Zhiqiang,Yang, Yunquan
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supporting information
p. 813 - 816
(2015/02/19)
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- Copper nanoparticles from copper aluminum hydrotalcite: An efficient catalyst for acceptor- and oxidant-free dehydrogenation of amines and alcohols
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An efficient and simple process for the preparation of stable nanocopper(0) on alumina [Cu(0)/Al2O3] from the inorganic composite precursor copper aluminum hydrotalcite (Cu-AlHT) by a chemical reduction method is described. Cu(0)/ Al2O3 was employed as an efficient catalyst in the acceptor- and oxidant-free dehydrogenation of various amines and alcohols to their corresponding dehydrogenated products in good to excellent yields. The stability of Cu(0)/Al2O3 was assessed by studying its recoverability and reusability in the dehydrogenation of amines and alcohols for up to five cycles.
- Damodara, Dandu,Arundhathi, Racha,Likhar, Pravin R.
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supporting information
p. 189 - 198
(2014/03/21)
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- Oxidation of primary and secondary alcohols to the corresponding carbonyl compounds with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO 3/Al2O3 as catalysts
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The oxidation of primary and secondary alcohols to their corresponding carbonyl compounds proceeds with high efficiency under molecular oxygen in the presence of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungsten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various aromatic, alicyclic, and aliphatic alcohols can be converted to their corresponding carbonyl compounds in excellent yields. It is noteworthy that the oxidative transformation of the alcohols proceeds chemoselectively in the presence of other functional groups. In addition, a plausible catalytic pathway is proposed.
- Zhu, Yaoqin,Xu, Jian,Lu, Ming
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