- Switchable Imine and Amine Synthesis Catalyzed by a Well-Defined Cobalt Complex
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Switchable imine and amine synthesis catalyzed by a tripodal ligand-supported well-defined cobalt complex is presented herein. A large variety of primary alcohols and amines were selectively converted to imines or amines in good to excellent yields. It is discovered that the base plays a crucial role on the selectivity. A catalytic amount of base leads to the imine formation, while an excess loading of base results in the amine product. This strategy on product selectivity also strongly depends on the organometallic catalysts in use. We expect that the present study could provide useful insights toward selective organic synthesis and catalyst design.
- Paudel, Keshav,Xu, Shi,Hietsoi, Oleksandr,Pandey, Bedraj,Onuh, Chuka,Ding, Keying
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supporting information
p. 418 - 426
(2021/02/01)
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- Crystal phase effect of iron oxides on the aerobic oxidative coupling of alcohols and amines under mild conditions: A combined experimental and theoretical study
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Selective catalytic oxidation using air as the terminal oxidant is an ecofriendly route for the synthesis of fine and commodity chemicals. However, the catalyst generally faces the challenges of the inertness of molecular oxygen, limited substrate scope, poor selectivity, and high cost. Moreover, the toxicity of the catalyst should also be considered when the products are used in pharmaceutical or biotechnological areas. Here, upon investigating the dependence of catalytic oxidation on the crystal phases of iron oxides, we find that naked γ-Fe2O3 particles exhibit excellent catalytic activity, selectivity, and stability in a series of imine synthetic reactions. The performance of γ-Fe2O3 particles is significantly better than that of α-Fe2O3 and Fe3O4 under mild reaction conditions, and the γ-Fe2O3 catalyst can be separated from the reaction mixture magnetically. Both experimental and theoretical calculation results show that γ-Fe2O3 possesses supercapability for oxygen activation. The inverse spinel structure of γ-Fe2O3 has abundant cation vacancies, which confers unique electronic properties on surface Fe species. These Fe species tend to transfer electrons to molecular oxygen to form O2? or O22? species. These oxygen species are favorable for the dehydrogenation of alcohols, which is responsible for the high activity of γ-Fe2O3 in this coupling reaction.
- Geng, Longlong,Jian, Wei,Jing, Pei,Zhang, Wenxiang,Yan,Bai, Fu-Quan,Liu, Gang
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p. 145 - 152
(2019/08/01)
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- Ruthenium(II)-(Arene)-N-Heterocyclic Carbene Complexes: Efficient and Selective Catalysts for the N-Alkylation of Aromatic Amines with Alcohols
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A series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides were synthesized as N-heterocyclic carbene (NHC) precursors. These compounds were used for synthesis of the new ruthenium(II) complexes of the type [RuCl2(arene)(NHC)], (arene = η6-p-cymene). The structures of all compounds were characterized by 1H NMR, 13C NMR and FT-IR spectroscopy techniques. The catalytic activity of the ruthenium complexes has been evaluated with respect to the mono-N-alkylation reactions of aromatic amines with various alcohol derivatives under solvent-free conditions at 120 °C using the borrowing hydrogen strategy.
- Kalo?lu, Nazan,Achard, Mathieu,Bruneau, Christian,?zdemir, ?smail
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supporting information
p. 2598 - 2606
(2019/06/14)
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- Oxidative coupling of alcohols and amines to an imine over Mg-Al acid-base bifunctional oxide catalysts
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A series of Mg-Al mixed oxide catalysts are prepared and introduced as efficient irreducible catalysts for the oxidative coupling of alcohols and amines to imine. The structure and surface properties of Mg-Al oxides are modulated by changing the Mg/Al ratios, calcination temperature and treatment with probe molecules. Detailed characterization, including X-ray diffraction, 27Al magic angle spinning nuclear magnetic resonance spectroscopy, N2-adsorption, NH3-temperature-programmed desorption, CO2-temperature-programmed desorption and X-ray photoelectron spectroscopy are carried out to determine the physicochemical properties of these catalysts. The Mg-Al oxides with Mg/Al = 3 exhibit the highest activity in the reaction, which possess a large number of surface weak basic sites and a relatively small number of weak acidic sites. The role of the acidic and basic sites in the reaction process is systematically investigated, and are shown to serve as adsorption and activation sites for amines and alcohols, respectively. Under the synergistic effect of these acid-base centers, the oxidative coupling process successfully occurs on the surface of Mg-Al mixed oxides. Compared with the acidic sites, the weak basic sites play a more important role in the catalytic process. The acidic sites are the catalytic centers for the benzyl alcohol activation, which control the reaction rate of the oxidative coupling reaction.
- Song, Jinling,Yu, Guiyang,Li, Xi,Yang, Xuwei,Zhang, Wenxiang,Yan, Wenfu,Liu, Gang
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p. 309 - 318
(2018/02/20)
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- Preparation method for imine compounds
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The invention relates to a preparation method for imine compounds. The preparation method comprises the following concrete steps: with toluene or derivatives thereof and aminated compounds as reaction substrates, adding an oxygen source under the action of a catalyst; putting the above-mentioned substances into a pressure container, enclosing the pressure container and carrying out a stirring reaction at 50 to 150 DEG C for 6 to 24 h; and carrying out oxidative condensation so as to prepare the imine compounds. The method is characterized in that a metal oxide is used as the catalyst. According to the method, raw materials are cheap and easily available; the prepared imine compounds are easily separable from the catalyst; the catalyst can be cyclically used; reaction process is simple, controllable and easy to operate; and the yield of the imine compounds is as high as 90%.
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Paragraph 0132; 0133
(2017/10/25)
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- Synthetic method of imine
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The invention relates to a method for preparing imine from an azo compound and an alcohol compound through hydrogen transition coupling. The method specifically comprises: dispersing and dissolving an azo compound and an alcohol compound which are taken as substrates in an organic solvent, adding a nickel-based catalyst, putting the obtained mixture in a synthesis kettle, leading inert gas in to replace internal air, performing sealing and stirring, carrying out a heating reaction, performing centrifugation to remove the catalyst after the reaction is over, performing rotary evaporation to remove the solvent, and performing purification through recrystallization to obtain the sample. In the catalytic action of different multi-phase nickel-based catalysts, the reaction is high in conversion rate and imine selectivity. The method is an atom economic reaction.
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Paragraph 0077; 0078
(2017/06/02)
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- A novel straightforward synthesis of α-aminophosphonates: one-pot three-component condensation of alcohols, amines, and diethylphosphite in the presence of CuO@Fe3O4 nanoparticles as a catalyst
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We report here a novel and straightforward synthesis method for the preparation of α-aminophosphonates in relatively good yield. The method involves the one-pot three-component condensation of alcohols, amines, and diethylphosphite in the presence of CuO@Fe3O4 nanoparticles as a recyclable catalyst. CuO@Fe3O4 nanoparticles were prepared and their structures were confirmed by the FT-IR, TGA, VSM, TEM and X-ray diffraction patterns analyses.
- Kaboudin, Babak,Kazemi, Foad,Hosseini, Narges Kadkhoda
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p. 4475 - 4486
(2017/07/22)
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- CeO2 nanorods anchored on mesoporous carbon as an efficient catalyst for imine synthesis
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CeO2 nanorods anchored on mesoporous carbon exhibit high activity and stability in aerobic oxidative coupling of alcohols and amines to imines. The abundant surface Ce3+ and the suitable interaction between CeO2 nanorods and the carbon support should be responsible for the excellent catalytic behaviors.
- Geng, Longlong,Song, Jinling,Zhou, Yahui,Xie, Yan,Huang, Jiahui,Zhang, Wenxiang,Peng, Luming,Liu, Gang
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supporting information
p. 13495 - 13498
(2016/11/19)
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- Aerobic oxidative coupling of alcohols and amines to imines over iron catalysts supported on mesoporous carbon
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Direct oxidative coupling of an alcohol and amine, with air or molecular oxygen as the oxygen source, is an environmentally friendly method for imine synthesis. We developed an Fe catalyst supported on mesoporous carbon (denoted by FeOx/HCMK-3) for this reaction with excellent activity and recyclability. FeOx/HCMK-3 was prepared by impregnating HNO3-treated mesoporous carbon (CMK-3) with iron nitrate solution. The highly dispersed FeOx species give FeOx/HCMK-3 high reducibility and are responsible for the high catalytic performance. Imine synthesis over FeOx/HCMK-3 follows a redox mechanism. The oxygen species in FeOx/HCMK-3 participate in the reaction and are then regenerated by oxidation with molecular O2. The reaction involves two consecutive steps: oxidative dehydrogenation of an alcohol to an aldehyde and coupling of the aldehyde with an amine to give an imine. Oxidative dehydrogenation of the alcohol is the rate-determining step in the reaction.
- Geng, Longlong,Song, Jinling,Zheng, Bin,Wu, Shujie,Zhang, Wenxiang,Jia, Mingjun,Liu, Gang
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p. 1451 - 1460
(2016/10/04)
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- Benzimidazolium sulfonate ligand precursors and application in ruthenium-catalyzed aromatic amine alkylation with alcohols
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New benzimidazolium sulfonate salts have been prepared and fully characterized. They have been associated in situ with [RuCl2(p-cymene)]2 to generate efficient catalytic systems operating at 120 °C under neat conditions in the presence of potassium tert-butylate for selective N-alkylation of primary aromatic amines into secondary amines.
- Kaloglu, Nazan,?zdemir, Ismail,Gürbüz, Nevin,Achard, Mathieu,Bruneau, Christian
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