588-04-5Relevant academic research and scientific papers
Invisible Silver Guests Boost Order in a Framework That Cyclizes and Deposits Ag3Sb Nanodots
Ahn, Dohyun,Cheng, Shengxian,Feng, Weijin,He, Jun,Hu, Jieying,Xin, Yinger,Xu, Zhengtao,Zeller, Matthias
, p. 5757 - 5763 (2021/05/04)
The infusion of metal guests into (i.e., metalating) the porous medium of metal-organic frameworks (MOFs) is a topical approach to wide-ranging functionalization purposes. We report the notable interactions of AgSbF6 guests with the designer MOF host ZrL1 [Zr6O4(OH)7(L1)4.5(H2O)4]. (1) The heavy-atom guests of AgSbF6 induce order in the MOF host to allow the movable alkyne side arm to be fully located by X-ray diffraction, but they themselves curiously remain highly disordered and absent in the strucutral model. The enhanced order of the framework can be generally ascribed to interaction of the silver guests with the host alkyne and thioether functions, while the invisible heavy-atom guest represents a new phenomenon in the metalation of open framework materials. (2) The AgSbF6 guests also participate in the thermocyclization of the vicinal alkyne units of the L1 linker (at 450 °C) and form the rare nanoparticle of Ag3Sb supported on the concomitantly formed nanographene network. The resulted composite exhibits high electrical conductivity (1.0 S/cm) as well as useful, mitigated catalytic activity for selectively converting nitroarenes into the industrially important azo compounds, i.e., without overshooting to form the amine side products. The heterogeneous/cyclable catalysis entails only the cheap reducing reagents of NaBH4, ethanol, and water, with yields being generally close to 90%.
Biogenic Synthesis of Gold Nanoparticles on a Green Support as a Reusable Catalyst for the Hydrogenation of Nitroarene and Quinoline
Adeyeye Nafiu, Sodiq,Aziz, Abdul,Shaheen Shah, Syed,Shaikh, M. Nasiruzzaman
, p. 1956 - 1966 (2021/06/18)
Direct attachment of gold nanoparticles to a green support without the use of an external reducing agent and using it for removing toxic pollutants from wastewater, i. e., reduction of nitroarene to amine, are described. A novel approach involving the reduction of gold by the jute plant (Corchorus genus) stem-based (JPS) support itself to form nanoparticles (AuNPs) to be used as a catalytic system (‘dip-catalyst’) and its catalytic activity for the hydrogenation of series of nitroarenes in aqueous media are presented. AuNPs/JPS catalyst was characterized using SEM, UV-Vis, FTIR, TEM, XPS, and ICP-OES. Confined area elemental mapping exhibits uniform and homogeneous distribution of AuNPs on the support surface. TEM shows multi-faceted AuNPs in the range of 20–30 nm. The reactivity of AuNPs/JPS for the transfer hydrogenation of nitroarene as well as hydrogenation of quinoline under molecular H2 pressure was evaluated. Sodium borohydride, when used as the hydrogen source, demonstrates a high catalytic efficiency in the transfer hydrogenation reduction of 4-nitrophenol (4-NP). Quinoline is quantitatively and chemoselectively hydrogenated to 1,2,3,4-tetrahydroquinoline (py-THQ) using molecular hydrogen. Reusability studies show that AuNPs are stable on the support surface and their selectivity is not affected.
Bifunctional Cs?Au/Co3O4 (Basic and Redox)-Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines
Akinnawo, Christianah Aarinola,Alimi, Oyekunle Azeez,Fapojuwo, Dele Peter,Meijboom, Reinout,Mogudi, Batsile M.,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
supporting information, p. 5063 - 5073 (2021/09/30)
An eco-friendly alkali-promoted (Cs?Au/Co3O4) catalyst, with redox and basic properties for the oxidative dehydrogenative coupling of anilines to symmetrical and unsymmetrical aromatic azo compounds, was developed. We realized a base additive- and molecular O2 oxidant-free process (using air), with reasonable reusability of the catalyst achieved under milder reaction conditions. Notably, the enhanced catalytic activity was also linked to the increased basic site concentration, low reduction temperatures, and the effect of lattice oxygen on the nanomaterials. The increased basic strength of the cation-promoted catalyst improved the electron density of the active Au species, resulting in higher yields of the desired aromatic azo compounds.
Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
supporting information, p. 1301 - 1307 (2020/03/11)
We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
Continuous and green microflow synthesis of azobenzene compounds catalyzed by consecutively prepared tetrahedron CuBr
Qin, Hong,Liu, Chengkou,Lv, Niuniu,He, Wei,Meng, Jingjing,Fang, Zheng,Guo, Kai
, (2019/12/24)
An environmentally friendly and cross-selective process intensification for the continuous synthesis of symmetric aromatic azo compounds by using self-made cuprous bromide as the catalyst under mild conditions in the microreactor was developed. A novel tetrahedron cuprous bromide catalyst which shows outstanding catalytic activity and satisfactory stability has been synthesized in continuous flow microreactor. The online immobilization of self-made cuprous bromide on the catalyst bed achieved oxidative coupling of aromatic amines (oxygen as oxidant) and high-performance gas–liquid–solid three-phase reaction, which strongly limited the possibility of undesired reaction pathways, improving product selectivity and reducing waste generation. Meanwhile, the yield of azo-coupling reaction was up to 98% under optimized condition. As compared with earlier traditional method (diazotization reaction) for synthesizing azobenzene, the designed micro-flow process displays signi?cant advances in terms of selectivity, waste emissions, sustainability and productivity. The combination of online immobilization of self-made cuprous bromide and precise and safe control through the microreactor provides a green solution for the industrial production of valuable aromatic azo compounds.
Selective Propargylation of Diaryl Azo Compounds Using Metallic Barium
Yanagisawa, Akira,Heima, Toshihiko,Watanabe, Kana,Haeno, Shun
supporting information, p. 1817 - 1822 (2020/09/02)
The Barbier-type propargylation of azo compounds with α,γ-disubstituted propargylic tosylates was achieved by using metallic barium as the promoter. Various propargylated hydrazines (α-adducts) were exclusively synthesized from the corresponding propargylic tosylates and azobenzenes (diaryldiazenes). The thus-obtained propargylic hydrazines were further efficiently converted into propargylic amines by reductive N-N bond cleavage. Benzidine rearrangement of the propargylic hydrazines was also attempted.
Immobilized antimony species on magnetite: A novel and highly efficient magnetically reusable nanocatalyst for direct and gram-scale reductive-coupling of nitroarenes to azoarenes
Zeynizadeh, Behzad,Faraji, Fariba
, p. 13112 - 13121 (2019/05/10)
In this study, magnetic nanoparticles of Fe3O4@SbFx from the immobilization of SbF3 on magnetite were synthesized. The prepared nanocomposite system was then characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry and inductively coupled plasma optical emission spectroscopy. Next, the catalytic activity of Fe3O4@SbFx MNPs was highlighted by one-pot reductive-coupling of aromatic nitro compounds to the corresponding azoarene materials with NaBH4. The reactions were carried out in refluxing EtOH within 6-25 min to afford the products in high yields. The reusability of the Sb-magnetite system was also studied for 6 consecutive cycles without significant loss of catalytic activity. This synthetic protocol provided several advantages in terms of introducing a novel catalytic system based on antimony species for direct and gram-scale preparation of azoarenes from nitroarenes, low loading of the nanocatalyst, mild reaction conditions, using ethanol as a green and economic solvent and high yield of the products.
Visible-light triggered selective reduction of nitroarenes to azo compounds catalysed by Ag@organic molecular cages
Chen, Gong-Jun,Xin, Wen-Ling,Wang, Jing-Si,Cheng, Jun-Yan,Dong, Yu-Bin
supporting information, p. 3586 - 3589 (2019/03/26)
Herein, a new Ag nanoparticle (Ag NP) loaded organic molecular cage is reported. The obtained Ag@1 can act as a highly efficient heterogeneous catalyst for the selective reduction of nitroarenes to azo compounds under visible-light irradiation.
Synthesis of 2 - fluoro aniline compounds of the method
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Paragraph 0092; 0094, (2019/05/15)
The invention discloses a method for synthesizing 2 - fluoro aniline compounds of the method, the method is: shown in formula Ia aniline compound of formula Ib α and β shown aniline compound as raw materials, through coupling reaction shown [...] azobenzene compound II, then the type II shown azobenzene compound with a palladium catalyst, fluorination reagent, additive, organic solvent, in the 30 - 150 °C temperature closed agitating the fluorination reaction, [...] compound of formula III, type III compounds are shown in the reaction under the action of a reducing [...] shown IV 2 - fluoro aniline compounds; this invention synthetic 2 - fluoro aniline compounds substrate wide adaptability, mild reaction conditions, the operation is simple, fluorinated and good selectivity, [...] aniline compounds is prepared by many drug molecule is an important intermediate and starting material, wide application prospects.
Method for catalytically synthesizing azobenzene compound through double-metal composite oxide
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Paragraph 0061; 0062, (2019/03/08)
The invention discloses a method for catalytically synthesizing an azobenzene compound through a double-metal composite oxide and belongs to the technical field of catalytic synthesis of azobenzene. According to the method disclosed by the invention, under the action of the double-metal composite oxide, air or oxygen is used as an oxidant, so that amines containing different substituent groups aredirectly oxidized and coupled under a moderate condition to synthesize the azobenzene compound. A catalysis system adopted by the method has moderate reaction conditions and high selectivity; the synthesis of the azobenzene compound can be efficiently catalyzed by carrying out reacting at 60 DEG C and in the air; transition metal which is cheap and easy to obtain and contains iron, cobalt, nickel, aluminum, manganese and copper is used as the double-metal composite oxide, so that the availability of a double-metal composite oxide catalyst is improved.
