- Electronic and steric factors for enhanced selective synthesis of 2-ethyl-1-hexanol in the Ir-complex-catalyzed Guerbet reaction of 1-butanol
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1-Butanol is a potential bio-based fermentation product obtained from cellulosic biomass. As a value-added chemical, 2-ethyl-1-hexanol (2-EH) can be produced by Guerbet conversion from 1-butanol. This work reports the enhanced catalytic Guerbet reaction of 1-butanol to 2-EH by a series of Cp*Ir complexes (Cp*: 1,2,3,4,5-pentamethylcyclopenta-1,3-diene) coordinated to bipyridine-type ligands bearing an ortho-hydroxypyridine group with an electron-donating group and a Cl? anion. The catalytic activity of the Cp*Ir complex increased by increasing the electron density of the bipyridine ligand when functionalized with the para-NMe2 and ortho-hydroxypyridine groups. A record turnover number of 14047 was attained. A mechanistic study indicated that the steric effect of the ethyl group on the α-C of 2-ethylhexanal (2-EHA) and the conjugation effect of C=C–C=O in 2-ethylhex-2-enal (2-EEA) benefits the high selectivity of 2-EH from 1-butanol by inhibiting the cross-aldol reaction of 2-EHA and 2-EEA with butyraldehyde. Nuclear magnetic resonance study revealed the formation of a carbonyl group in the bipyridine-type ligand via the reaction of the Cp*Ir complex with KOH.
- Xu, Zhanwei,Yan, Peifang,Liang, Changhui,Jia, Songyan,Liu, Xiumei,Zhang, Z. Conrad
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p. 1586 - 1592
(2021/05/10)
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- Layered double hydroxide derived NiAl-oxide hollow nanospheres for selective transfer hydrogenation with improved stability
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Selective transfer hydrogenation (STH) is an efficient strategy in biomass upgradation, especially for the production of unsaturated alcohols from biomass-derived α,β-unsaturated aldehydes. Design of effective catalysts with excellent stability for the STH is highly desired. Here, we report the synthesis of Ni3Al1-oxide hollow nanospheres (h-Ni3Al1-800) derived from Ni3Al1 layered double hydroxide grafted on hollow polymer spheres (HPS?Ni3Al1-LDH) by calcination at 800 °C in air. h-Ni3Al1-800 is an efficient catalyst for the STH of α,β-unsaturated aldehydes with selectivities towards α,β-unsaturated alcohols >99% at almost full conversions. More importantly, h-Ni3Al1-800 can be recycled at least 12 times without loss of activity. Experimental results and DFT calculations prove that the Al dopant in h-Ni3Al1-800 provides much stable Niδ+-type (2 δ 3) acid-base pairs which can efficiently catalyze the STH with improved stability. This work provides a promising direction for the design of STH catalysts that have potential for industrial applications. This journal is
- Gong, Bingbing,Jiang, Haibin,Luo, Rong,Pan, Zhengyi,Wang, Guang-Hui,Zhang, Wenhua
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supporting information
p. 23376 - 23384
(2020/11/25)
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- Method for synthesizing unsaturated primary alcohol
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The invention discloses a method for synthesizing an unsaturated primary alcohol. The method comprises the following steps: adding an unsaturated aldehyde, a transition metal catalyst iridium complexand isopropyl alcohol in a reaction container, heating the reaction mixture in an oil bath, carrying out a reaction for a plurality of hours, then carrying out cooling to room temperature, removing the solvent by rotating evaporation, and then carrying out column separation to obtain the target compound. According to the invention, the unsaturated aldehyde is used as a raw material, isopropyl alcohol is used as a hydrogen source and the solvent, and the unsaturated primary alcohol is generated through hydrogen transfer under participation of the transition metal iridium catalyst. The method has the following remarkable advantages: 1) the reaction temperature is low; 2) cheap, safe and non-toxic isopropanol is used; 3) the catalyst usage amount is low, and reaction atom economy is high; and4) selectivity is good. Therefore, the method meets the requirements of green chemistry and has a wide development prospect.
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Paragraph 0079-0083
(2019/08/20)
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- Transfer-hydrogenation process
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A transfer-hydrogenation process for preparing a carbonyl compound and an alcohol compound comprises the steps of (a) contacting a first carbonyl compound with a first alcohol compound in the presence of a transfer-hydrogenation catalyst in a first reaction zone at conditions effective to form a second carbonyl compound from the first alcohol compound and a second alcohol compound from the first carbonyl compound, and (b) removing the second carbonyl compound from the first reaction zone during step (a). The first carbonyl compound is a saturated aldehyde or ketone, or an α,β-unsaturated aldehyde or ketone. The first alcohol compound is a primary or secondary alcohol. The second alcohol compound is α,β-saturated. The transfer-hydrogenation catalyst includes a Group 8 to 11 metal. This process is useful for preparing and higher value alcohols, such as butanol or 2-ethylhexanol, from the corresponding carbonyl compounds by engaging lower alcohol (C2-C4) feedstocks instead of hydrogen (H2).
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Page/Page column 18
(2018/06/19)
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- Transfer Hydrogenation of Aldehydes and Ketones with Isopropanol under Neutral Conditions Catalyzed by a Metal-Ligand Bifunctional Catalyst [Cp?Ir(2,2′-bpyO)(H2O)]
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A Cp?Ir complex bearing a functional bipyridonate ligand [Cp?Ir(2,2′-bpyO)(H2O)] was found to be a highly efficient and general catalyst for transfer hydrogenation of aldehydes and chemoselective transfer hydrogenation of unsaturated aldehydes with isopropanol under neutral conditions. It was noteworthy that many readily reducible or labile functional groups such as nitro, cyano, ester, and halide did not undergo any change under the reaction conditions. Furthermore, this catalytic system exhibited high activity for transfer hydrogenation of ketones with isopropanol. Notably, this research exhibited new potential of metal-ligand bifunctional catalysts for transfer hydrogenation.
- Wang, Rongzhou,Tang, Yawen,Xu, Meng,Meng, Chong,Li, Feng
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p. 2274 - 2281
(2018/02/23)
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- Direct synthesis of 2-ethylhexanol via n-butanal aldol condensation-hydrogenation reaction integration over a Ni/Ce-Al2O3 bifunctional catalyst
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Direct synthesis of 2-ethylhexanol from n-butanal via the reaction integration of n-butanal self-condensation with 2-ethyl-2-hexenal hydrogenation is of crucial interest for industrial production of 2-ethylhexanol. Furthermore, as an important and versatile chemical, n-butanol can be produced simultaneously by reaction integration. In the present work, several bifunctional catalysts based on γ-Al2O3 were prepared by the impregnation method and were characterized by means of H2-TPR, XRD, TEM and H2-TPD, and their catalytic performance for direct synthesis of 2-ethylhexanol from n-butanal was investigated. The results showed that Co/Al2O3 had a low activity for hydrogenation and Cu/Al2O3 had a high selectivity for the hydrogenation of the C=O group while a Ru/Al2O3 catalyst only favored the hydrogenation of n-butanal to n-butanol. Among them, the Ni/Al2O3 catalyst showed the best catalytic performance and the yield of 2-ethylhexanol was the highest (49.4%). Ce-modified Ni/Al2O3 enhanced the competitiveness of aldol condensation versus hydrogenation of n-butanal and improved the selectivity of 2-ethylhexanol; the yield of 2-ethylhexanol rose to 57.8%. Then the influence of preparation conditions on the catalytic performance of Ni/Ce-Al2O3 was investigated and the suitable preparation conditions were obtained as follows: Ni loading = 10%, calcined at 550 °C for 5 h, and reduced at 570 °C for 4 h. The effect of reaction conditions on the integration reaction catalyzed by Ni/Ce-Al2O3 was investigated and the suitable reaction conditions were obtained as follows: weight percentage of Ni/Ce-Al2O3 = 15%, reaction temperature = 170 °C, reaction pressure = 4.0 MPa and reaction time = 8 h. Under the above reaction conditions, the yield of 2-ethylhexanol attained 66.9% and that of n-butanol was 18.9%. In addition, the components existing in the integration reaction system were identified by GC-MS analysis, and the main by-products were n-butyl butyrate, 2-ethylhexyl butyrate, n-butyric acid, etc. Based on the analysis of the reaction system, a reaction network for the direct synthesis of 2-ethylhexanol from n-butanal was proposed. Finally, an evaluation of the reusability of Ni/Ce-Al2O3 showed that the recovered Ni/Ce-Al2O3 catalyst lost its catalytic activity for the hydrogenation of the C=O group. The main reason for deactivation was that Ni species were covered by the flaky boehmite γ-AlO(OH) formed from the hydration of γ-Al2O3 in the reaction process.
- Liang, Ning,Zhang, Xiaolong,An, Hualiang,Zhao, Xinqiang,Wang, Yanji
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p. 2959 - 2972
(2015/05/27)
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- Hollow Ni-Co-B amorphous alloy nanospheres: Facile fabrication via vesicle-assisted chemical reduction and their enhanced catalytic performances
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In this paper, we develop a simple vesicle-assisted chemical reduction approach for synthesizing hollow Ni-Co-B nanospheres. With various characterization techniques, the resulting Ni-Co-B nanospheres are identified as amorphous alloys with a hollow chamber. Coexistence of NiII and CoII species plays a significant role in fabricating hollow nanospheric structures, because only solid nanoparticles can be obtained in the presence of a mono-metallic precursor. During liquid-phase hydrogenation of 2-ethyl-2-hexenaldehyde, hollow Ni-Co-B catalyst displays significant bi-site catalysis from bimetals and delivers much greater activity as well as better selectivity than associated with the dense Ni-Co-B catalyst. Additionally, this catalyst is also easily handled in liquid-phase reactions due to its lower density and magnetic property. The material design concept presented in this work opens a new avenue for the development of hollow non-noble metallic nanospheres and will draw more attention in the foreseeable future.
- Wei,Zhao,Peng,Zhang,Bian,Li,Li
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supporting information
p. 19253 - 19259
(2015/02/05)
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- Highly dispersed Pd on Co-B amorphous alloy: Facile synthesis via galvanic replacement reaction and synergetic effect between Pd and Co
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In this paper, uniform Co-B amorphous alloy nanospheres with an average particle size of 50 nm were synthesized by chemical reduction of cobalt ion with borohydride in aqueous solution containing Bu4PBr and KCl. Then, Pd was introduced into this system by galvanic replacement reaction (GRR) between Co and Na2PdCl4. Pd/Co-B catalysts with different Pd content could be obtained via adjusting the amount of Na2PdCl 4 in reaction mixture. The crystal structure, morphology, and surface electronic state of as-prepared catalysts were characterized by XRD, TEM, XPS, and H2-TPD. During the liquid-phase hydrogenation of 2-ethyl-2-hexenaldehyde, the as-prepared Pd/Co-B catalysts exhibited extremely active and more selectivity to 2-ethyl-1-hexanol than the monometallic Pd and Co-B amorphous alloy, showing potential application in industry. The enhanced performances could be attributed to the highly dispersed Pd on the surface of Co-B prepared by GRR and the synergetic effect between Pd and Co.
- Li, Hui,Ma, Jinqiang,Xu, Liang,Xu, Lei,Wang, Hao,Xu, Sen,Li, Hexing,Xie, Songhai
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p. 985 - 992
(2013/07/25)
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- REACTIVE DILUENTS
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Allyloxy esters, RnM(OR')x(OR")y, wherein M is silicon, carbon, boron or titanium, R is hydrogen or a hydrocarbyl group, R' are allylic unsaturated hydrocarbyl or hydrocarbyloxy hydrocarbyl groups, R" are saturated analogues of R', and x is at least 1 and y may be zero, and n + x + y = 3 if M is boron, and n + x + y = 4if M is silicon, carbon, or titanium, are used as reactive diluents in paint or coating formulations.
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