538-51-2Relevant articles and documents
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Drapier et al.
, p. 484 (1972)
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MnOX supported on a TiO2@SBA-15 nanoreactor used as an efficient catalyst for one-pot synthesis of imine by oxidative coupling of benzyl alcohol and aniline under atmospheric air
Mandal, Sandip,Maity, Sudip,Saha, Sujan,Banerjee, Biplab
, p. 73906 - 73914 (2016)
In the present study, a mesoporous silica (SBA-15) encapsulated TiO2 nanoreactor is used as a support for MnOx and this MnOx/TiO2@SBA-15 acts as a catalyst for the one-pot synthesis of imine by oxidative coupling between benzyl alcohol and aniline in the presence of atmospheric air. To understand the properties, the catalysts were characterized by several analytical techniques, namely, N2 adsorption-desorption isotherm, small angle X-ray scattering (SAXS), wide angle X-ray diffraction, high resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR), O2-temperature programmed oxidation (O2-TPO) and NH3-temperature programmed desorption (NH3-TPD). The pore encapsulation process by SBA-15 causes TiO2 to be in a highly dispersed state, and this highly dispersed TiO2 makes maximum contact with the MnOx species as well as the reactant molecules. The reaction was carried out at atmospheric pressure with equimolar amounts of substrates without additives in the presence of atmospheric air. The yield and selectivity of imines vary with the MnOx and TiO2 loading. The 7.5 wt% MnOx loaded TiO2@SBA-15 (5 wt% TiO2) nanoreactor showed the highest catalytic activity. With the increase in weak acid sites and the oxygen activation ability of the prepared catalyst, the conversion and selectivity of the desired product reached 96% and 97%, respectively. The investigation of the reaction mechanism suggests that there is a synergistic effect between highly dispersed TiO2 and MnOx, which improves the reactant conversion and the selectivity of the desired product (N-benzylideneaniline) and also the prepared catalyst shows excellent recyclability up to the 10th cycle. The recyclability and hot filtration study confirms the true heterogeneity of the prepared catalyst during imine synthesis. The heterogeneity of the prepared catalyst, the avoidance of any noble metal and the utilization of air as an oxidizing agent represent an efficient, green reaction pathway for imine synthesis.
Postsynthetic modification of an imine-based microporous organic network
Kerneghan, Phillip A.,Halperin, Shira D.,Bryce, David L.,Maly, Kenneth E.
, p. 577 - 582 (2011)
A highly cross-linked microporous organic network with imine linkers was prepared by condensation of tetrakis(4-aminophenyl)methane with terephthaldehyde. Gas adsorption studies indicate that the material exhibits permanent microporosity, and guest exchan
AMMONIUM PHOSPHONIUM SALTS
Romanov, G. V.,Lapin, A. A.,Pudovik, A. N.
, p. 669 - 670 (1984)
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Catalytic stereoselective Mannich reaction under solvent-free conditions
Azizi, Najmadin,Baghi, Roya,Batebi, Elham,Bolourtchian, Seyed Mohammad
, p. 278 - 282 (2012)
Silicon tetrachloride catalyzed one-pot three-component Mannich reaction of cyclic ketones, aromatic aldehydes, and aromatic amine under solvent-free conditions affords the corresponding β-amino ketones with excellent yield and good to excellent anti-selectivity.
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Houlden,Csizmadia
, p. 1137,1149 (1969)
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Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity
Ding, Huihui,Yang, Jingxia,Ma, Shuyi,Yigit, Nevzat,Xu, Jingli,Rupprechter, Günther,Wang, JinJie
, p. 4100 - 4108 (2018)
Large nano-structured flakes of CeO2 (20–80 nm in thickness, up to 5.6 μm in diameter) were synthesized by a combination of microwave (MW), ultraviolet (UV) and ultrasound (US), with or without pressure (P). The CeO2 structures were systematically examined by XRD, SEM, N2 sorption, HRTEM, XPS, Raman and H2-TPR. The synthesized CeO2 nanoflakes were composed by 3.0–7.5 nm nanoparticles with the (111) surface exposed, and laminated to nanoflakes with 3.42–3.85 nm nano-channels in between. MW-assisting was beneficial to form a higher surface Ce3+/(Ce3++Ce4+) ratio and surface oxygen vacancies during short synthesis procedure. A Raman peak at 480 cm?1 correlating with bulk Ce3+ was detected. H2-TPR found MW and MW+P had more surface Ce3+ (surface oxygen vacancies). CO oxidation and imine conversion proved that MW+P was the optimum condition to produce highly active CeO2 nanoflakes. The much better catalytic performance than CeO2 from solvothermal preparation, due to the larger channel gap (3.85 nm),a higher Ce3+/(Ce3++Ce4+) ratio (32 %) and more surface oxygen vacancies on the particles of the organized flake structures.
Thermal Cyclisation Reactions of Vinylogous Aminomethylene Meldrum's Acid Derivatives
McNab, Hamish,Monahan, Lilian C.,Gray, Thomas
, p. 140 - 141 (1987)
Flash vacuum pyrolysis of vinylogous aminomethylene derivatives of Meldrum's acid leads to new cyclisation reactions; one additional double bond results in the formation of 1H-azepin-3(2H)-ones, while two additional double bonds lead to benzamide derivatives.
A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
Nelson, Peter N.,Robertson, Tahjna I.
, (2021/10/12)
The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
Ammonium iodide-catalyzed radical-mediated tandem cyclization of aromatic aldehydes, arylamines and 1,4-dioxane
Deng, Jiyong,Liao, Yunfeng,Qi, Hongrui,Tao, Qiang,Xie, Yanjun,Yan, Yiyan,Yi, Bing,Zhang, Weijie
, p. 959 - 965 (2022/02/03)
We have developed a novel approach for the construction of 2-((2-arylquinolin-4-yl)oxy)ethan-1-ol derivatives by an NH4I-catalyzed radical-mediated tandem cyclization of three components including aromatic aldehydes, arylamines and 1,4-dioxane.
One-Pot Synthesis of Schiff Bases by Defect-Induced TiO2- x-Catalyzed Tandem Transformation from Alcohols and Nitro Compounds
Chen, Liyong,Fang, Qiang,Shen, Xiaoshuang,Tong, Jing,Wang, Jinfeng,Wang, Yao,Zhang, Hui
supporting information, p. 10715 - 10721 (2021/07/26)
Schiff bases that are generally formed from condensation reactions of aldehydes (or ketones) and amino groups could also be produced by a photodriven one-pot tandem reaction between alcohols and nitro compounds, in our case. Herein, TiO2-x porous cages derived from NH2-MIL-125 by a self-sacrificing template route are used to study the organic transformation and exhibit 100% conversion efficiency of nitrobenzene and 100% selectivity for Schiff bases in the system of benzyl alcohol (5 mL) and nitrobenzene (41 μL) upon light irradiation, but hydrogen by dehydrogenation of benzyl alcohol cannot be detected. Successful occurrence of the organic transformation is mainly attributed to Ti(III)-oxygen vacancy associates. Surface oxygen vacancy-related Ti(III) sites are responsible for binding with nitro groups, and low-coordinated Ti5c sites selectively adsorb hydroxyl groups of benzyl alcohol. The Ti(III) and oxygen vacancy associates capture photogenerated electrons for achievement of multielectron reduction of nitrobenzene and the subsequent Schiff base condensation reaction with the as-formed benzaldehyde.
