14572-89-5Relevant articles and documents
Selective Hydrogenation by Carbocatalyst: The Role of Radicals
Ahmad, Muhammad Sohail,He, Huixin,Nishina, Yuta
, p. 8164 - 8168 (2019)
The selective hydrogenation of the nitro moiety is a difficult task in the presence of other reducible functional groups such as alkenes or alkynes. We show that the carbon-based (metal-free) catalyst can be used to selectively reduce substituted nitro groups using H2 as a reducing agent, providing a great potential to replace noble-metal catalysts and contributing to simple and greener strategies for organic synthesis.
[N,P]-pyrrole-phosphine ligand: An efficient and robust ligand for Ru-catalyzed transfer hydrogenation microwave-assisted reactions
Sánchez-Rodríguez,Fragoso-Medina,Ramírez-Meneses,Gouygou,Ortega-Alfaro,López-Cortés
, p. 49 - 54 (2018)
A pyrrolyl-containing [N-P]-ligand (L1) and [Ru] were evaluated as catalytic system in transfer hydrogenation reaction of ketones. A comparison between microwave irradiation vs conventional heating conditions indicates that MW can be successfully used as energy source, improving the reaction time. The L1/Ru(II) proved to be an active, efficient and robust catalytic system. The scope of this catalytic system was evaluated using a diversity of substrates that include electron-withdrawing and electron-donor groups achieving a range of 65 to 95% conversion. Moreover, the catalytic system showed good activity even with highly sterically hindered ketones.
Facile Synthesis and Tunable Porosities of Imidazolium-Based Ionic Polymers that Contain In Situ Formed Palladium Nanoparticles
Wang, Yangxin,Zhong, Hong,Li, Liuyi,Wang, Ruihu
, p. 2234 - 2240 (2016)
A series of porous imidazolium-based ionic polymers that contain in situ formed Pd nanoparticles (Pd@PIPs) was synthesized by a Suzuki–Miyaura cross-coupling reaction in the presence of SiO2 particles. The hierarchical porosities of Pd@PIPs can be regulated well by adjusting the dosage of SiO2. Pd nanoparticles are formed concomitantly and encapsulated uniformly within the pores of the polymers. The appropriate usage of SiO2 templates results in a clear enhancement of the catalytic activity in the hydrogenation of nitroarenes without the addition of extra Pd species. The excellent catalytic performances are attributed to abundant meso- and macropores that facilitate the mass transfer of substrates during catalytic reactions.
Synthesis and characterization of silica-coated magnetite nanoparticles modified with bis(pyrazolyl) triazine ruthenium(II) complex and the application of these nanoparticles as a highly efficient catalyst for the hydrogen transfer reduction of ketones
Mobinikhaledi, Akbar,Moghanian, Hassan,Ajerloo, Bahram,Dousti, Fatemeh
, (2020)
We present a facile and efficient method for modifying the surface of silica-coated Fe3O4 magnetic nanoparticles (MNPs) with bis(pyrazolyl) triazine ruthenium(II) complex [MNPs@BPT–Ru (II)]. Field emission-scanning electron microscopy, thermogravimetric/derivative thermogravimetry analysis, X-ray powder diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and energy-dispersive X-ray spectrometry analyses were employed for characterizing the structure of these nanoparticles. MNPs@BPT–Ru(II) nanoparticles proved to be a magnetic, reusable, and heterogeneous catalyst for the hydrogen transfer reduction of ketone derivatives. In addition, highly pure products were obtained with excellent yields in relatively short times in the presence of this catalyst. A comparison of this catalyst with those previously used for the hydrogen transfer reactions proved the uniqueness of MNPs@BPT–Ru(II) nanoparticle which is due to its inherent magnetic properties and large surface area. The presented method also had other advantages such as simple reaction conditions, eco-friendliness, high recovery ability, easy work-up, and low cost.
Study of liquid-phase dehydration of d,l-1-(4-Aminophenyl)ethanol in the presence of acid catalysts
Schul'tsev,Panarin
, p. 1309 - 1313 (2010)
Thermal acid-catalyzed liquid-phase dehydration of 1-(4-aminophenyl)ethanol at 250-260°C and 30-100 mm Hg was studied. In the presence of KHSO 4 a 2:1 mixture of 1-amino-4-ethylbenzene with 4-aminostyrene is formed, the use of KHSO4/KH2PO4 causes the formation of polymers, and the use of H3BO3 (≤ 0.26 wt %) in a mixture with KHSO4 allows the preparation of pure 4-aminostyrene. The structure of the reaction products was confirmed by NMR spectroscopy and by authentic synthesis. Pleiades Publishing, Ltd., 2010.
Hydrogenation of 4-nitroacetophenone over Rh/silica
Currall, Kathryn,Jackson, S. David
, p. 59 - 63 (2014)
The hydrogenation of 4-nitroacetophenone (4-NAP) and 4-aminoacetophenone (4-AAP) was examined over rhodium/silica catalysts. The reactions were carried out using isopropanol as the solvent under a range of temperatures (303-333 K) and pressures (1-5 barg). An activation energy of 50 ± 4 kJ mol -1 was determined for 4-NAP hydrogenation and 48 ± 2 kJ mol-1 for 4-AAP hydrogenation. Orders of reaction were obtained for 4-NAP (zero order) and hydrogen (first order) and a kinetic isotope effect of 3.0 was observed for 4-NAP hydrogenation and ～1.4 for 4-AAP hydrogenation when deuterium was used. Under specific conditions high yields (～94%) to 4-aminoacetophenone and 1-(4-aminophenyl) ethanol could be obtained from 4-NAP hydrogenation. An antipathetic metal crystallite particle size effect was observed for both reactants.
Ni Nanoparticles Stabilized by Poly(Ionic Liquids) as Chemoselective and Magnetically Recoverable Catalysts for Transfer Hydrogenation Reactions of Carbonyl Compounds
Vijayakrishna, Kari,Charan, K. T. Prabhu,Manojkumar, Kasina,Venkatesh, Sadhana,Pothanagandhi, Nellepalli,Sivaramakrishna, Akella,Mayuri, Pinapeddavari,Kumar, Annamalai Senthil,Sreedhar
, p. 1139 - 1145 (2016)
Imidazolium-based poly(ionic liquids) with hydroxide as the counter anion were employed to prepare stable aqueous dispersion of Ni nanoparticles. The synthesized poly(ionic liquid) stabilized Ni nanoparticles (PIL-Ni-NPs) were characterized by thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), powder XRD, TEM, Brunauer-Emmett-Teller (BET) surface area measurements, X-ray photoelectron spectroscopy (XPS), EPR, and UV/Vis spectroscopy. The PIL-Ni-NPs possess good catalytic activity towards transfer hydrogenation (TH) reactions of carbonyl compounds to their alcohol derivatives, in isopropanol at 80 °C in the absence of any additional base. This catalyst system chemoselectively reduces only the carbonyl group of α,β unsaturated carbonyl compounds. The magnetically separable PIL-Ni-NPs were recycled and reused for further TH reactions.
Optimizing selective partial hydrogenations of 4-nitroacetophenone via parallel reaction screening
Hawkins, Joel M.,Makowski, Teresa W.
, p. 328 - 330 (2001)
The hydrogenation of 4-nitroacetophenone was optimized for selective reduction to the corresponding aniline-ketone (97%), aniline-alcohol (95%), and aniline-methylene (99%) as a case study demonstrating the optimization of the selective reduction of a polyfunctional substrate using a parallel pressure reactor. The catalyst, catalyst loading, pressure, temperature, and methanesulfonic acid stoichiometry were varied, first in an initial coarse screen (catalyst and acid stoichiometry), and then in a full factorial screen for selected catalysts. Facile profiling of hydrogen uptake in each reaction aided setting reaction time and parameter ranges for the full factorial analysis, allowed for quickly spotting under-and overreduction, aided predicting robust reaction endpoints, and provided data for analyzing kinetic behavior.
Catalytic Transfer Hydrogenation with a Methandiide-Based Carbene Complex: An Experimental and Computational Study
Weismann, Julia,Gessner, Viktoria H.
, p. 16103 - 16112 (2015)
The transfer hydrogenation (TH) reaction of ketones with catalytic systems based on a methandiide-derived ruthenium carbene complex was investigated and optimised. The complex itself makes use of the noninnocent behaviour of the carbene ligand (M=CR2→MH-C(H)R2), but showed only moderate activity, thus requiring long reaction times to achieve sufficient conversion. DFT studies on the reaction mechanism revealed high reaction barriers for both the dehydrogenation of iPrOH and the hydrogen transfer. A considerable improvement of the catalytic activity could be achieved by employing triphenylphosphine as additive. Mechanistic studies on the role of PPh3 in the catalytic cycle revealed the formation of a cyclometalated complex upon phosphine coordination. This ruthenacycle was revealed to be the active species under the reaction conditions. The use of the isolated complex resulted in high catalytic activities in the TH of aromatic as well as aliphatic ketones. The complex was also found to be active under base-free conditions, suggesting that the cyclometalation is crucial for the enhanced activity.
Rhodium nanoparticles supported on 2-(aminomethyl)phenols-modified Fe3O4 spheres as a magnetically recoverable catalyst for reduction of nitroarenes and the degradation of dyes in water
Chen, Tian,Chen, Zhangpei,Hu, Jianshe,Lv, Kexin,Reheman, Aikebaier,Wang, Gongshu
, (2021/06/18)
A magnetic nanostructured catalyst (Fe3O4@SiO2-Amp-Rh) modified with 2-(aminomethyl)phenols (Amp) was designed and prepared, which is used to catalyze the reduction of aromatic nitro compounds into corresponding amines and the degradation of dyes. The 2-aminomethylphenol motif plays a vital role in the immobilization of rhodium nanoparticles to offer extraordinary stability, which has been characterized by using various techniques, including transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), X-Ray Diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A variety of nitroaromatic derivatives have been reduced to the corresponding anilines in water with up to yields of 99% within 1?h at room temperature. In addition, the catalyst system is effective in catalyzing the reduction of toxic pollutant 4-nitrophenol and the degradation of MO, MB and RhB dyes. Importantly, this catalyst Fe3O4@SiO2-Amp-Rh can be easily recovered by an external magnetic field because of the presence of magnetic core of Fe3O4, and the activity of Fe3O4@SiO2-Amp-Rh does not decrease significantly after 7 times’ recycling, which indicates that the catalyst performed high reactivity as well as stability. Graphical abstract: [Figure not available: see fulltext.]
