586-96-9Relevant articles and documents
An effective medium of H2O and low-pressure CO2 for the selective hydrogenation of aromatic nitro compounds to anilines
Meng, Xiangchun,Cheng, Haiyang,Fujita, Shin-Ichiro,Yu, Yancun,Zhao, Fengyu,Arai, Masahiko
, p. 570 - 572 (2011)
Chemoselective hydrogenation of water-insoluble aromatic nitro compounds can be achieved over Ni catalysts in a H2O-compressed CO2 system at 35-50 °C without using any environmentally harmful solvent. The effective CO2 pressure is much lower than the critical pressure of CO2. The hydrogenation of nitro group should be the rate-determining step. The Royal Society of Chemistry.
Dimeric assemblies of lanthanide-stabilised dilacunary Keggin tungstogermanates: A new class of catalysts for the selective oxidation of aniline
Trautwein, Guido,El Bakkali, Bouchra,Alca?iz-Monge, Juan,Artetxe, Be?at,Reinoso, Santiago,Gutiérrez-Zorrilla, Juan M.
, p. 110 - 117 (2015)
In this work we demonstrate the efficiency of some dimeric [Ln4(H2O)6(β-GeW10O38)2]12- anions composed of lanthanide-stabilised dilacunary Keggin tungstogermanate fragments (ββ-Ln4, Ln = Dy, Ho, Er, Tm) as heterogeneous catalysts for the organic phase oxidation of aniline with hydrogen peroxide. The results obtained evidence total conversion of aniline at room temperature, as well as full selectivity towards nitrosobenzene, and the catalysts are able to retain both their activity and selectivity after several runs. Peroxopolyoxometalate intermediaries have been identified as the catalytically active species during the aniline-to-nitrosobenzene oxidation process.
Fabrication of hybrid mesoporous TiO2-SiO2(Et) supported Ni nanoparticles: An efficient and air/water stable catalyst
Li, Wei,Cheng, Haiyang,Lin, Weiwei,Liang, Guanfeng,Zhang, Chao,Zhao, Fengyu
, p. 214 - 221 (2016)
We prepared a series of mesostructured Ni/TiO2-SiO2(Et) hybrid catalysts with highly dispersed Ni nanoparticles and incorporated ethane-bridged organosilica moieties. Ni/TiO2-SiO2(Et) showed high activity in the hydrogenation of nitrobenzene in water, and it could be recycled for several times with a constant activity and selectivity. It was confirmed that Ni/TiO2-SiO2(Et) catalyst is of hydrophobicity as the ethane-bridged organosilica fragments were incorporated into the mesoporous framework, and so the Ni active species was protected without contacting with water to form the inactive Ni species. In particularly, the Ni/TiO2-SiO2(Et) catalyst was air-stable, it could remain good activity after being exposed to air for a week. Accordingly, this work developed a kind of hydrophobic Ni catalyst with high stability to water and air, which is expected to have a wide application in the hydrogenation reactions.
Radical Cations of Nitroso Derivatives. A Radiation-chemical and Electron Spin Resonance Study
Chandra, Harish,Keeble, David J.,Symons, Martyn C. R.
, p. 609 - 616 (1988)
Exposure of dilute solutions containing nitrosobenzene in trichlorofluoromethane to 60Co γ-rays at 77 K gave the corresponding radical cation, characterised by e.s.r. spectroscopy.The results confirm the interpretation of liquid-phase data assigned to this cation, which showed that loss is from an in-plane ?-orbital localised on nitrogen and oxygen, rather than from the aromatic ?-system.However, solutions containing the t-butyl derivative in equilibrium with its dimer, (Me3CNO)2, gave primarily the dimer cation, (Me3CNO)2+, with possible traces of the monomer cation.The e.s.r. data for the latter resemble those for the nitrosobenzene cation, whereas results for the dimer cation suggest that loss is from a ?-type orbital with very low spin density on the two equivalent nitrogen atoms.
Continuous proline catalysis via leaching of solid proline
Opalka, Suzanne M.,Longstreet, Ashley R.,Tyler McQuade
, p. 1671 - 1679 (2011)
Herein, we demonstrate that a homogeneous catalyst can be prepared continuously via reaction with a packed-bed of a catalyst precursor. Specifically, we perform continuous proline catalyzed α-aminoxylations using a packed-bed of L-proline. The system relies on a multistep sequence in which an aldehyde and thiourea additive are passed through a column of solid proline, presumably forming a soluble oxazolidinone intermediate. This transports a catalytic amount of proline from the packed-bed into the reactor coil for subsequent combination with a solution of nitrosobenzene, affording the desired optically active α-aminooxy alcohol after reduction. To our knowledge, this is the first example in which a homogeneous catalyst is produced continuously using a packedbed. We predict that the method will not only be useful for other L-proline catalyzed reactions, but we also foresee that it could be used to produce other catalytic species in flow.
The Active Sites of Manganese- and Cobalt-Containing Catalysts in the Selective Gas Phase Reduction of Nitrobenzene
Maltha, A.,Kist, H. F.,Brunet, B.,Ziolkowski, J.,Onishi, H.,et al.
, p. 356 - 363 (1994)
The active sites of the spinels Mn3O4 and Co3O4 in the selective reduction of nitrobenzene to nitrosobenzene have been investigated, by total and partial substitution of Mnn+ (Con+) ions in tetrahedral position and/or Mnn+ (Con+) ions in octahedral position by redox-inactive ions.Investigation of the catalytic activities of the totally substituted manganese spinel ZnMn2O4 and that of the totally substituted cobalt spinels CoAl2O4 and ZnCo2O4 showed that the manganese and cobalt ions in octahedral position were responsible for the activity of the reaction.MnAl2O4, however, also showed some activity for the selective reduction of nitrobenzene, which should be due to surface enrichment and/or oxidative transfer of manganese from tetrahedral sites to octahedral sites.XRD results of the partially substituted spinels MnxZn1-xAl2O4 showed that was a linear correlation between the manganese concentration expressed by x and the lattice constant.Morever, each sample showed segregation of Al2O3; again there was a linear correlation between x in certain series of MnxZn1-xAl2O4 and the amount of free Al2O3.This points to an oxidative transfer of manganese from tetrahedral sites to octahedral sites.XPS showed that the concentration of manganese in the surface layers corresponded roughly to the value x, but the concentration of zinc in the surface layers was much smaller than expected.The catalytic activities of the MnxZn1-xAl2O4 series of catalysts are larger than would be expected from the result on ZnMnO4 and ZnCo2O4.
-
Derovane et al.
, p. 196,200 (1974)
-
Azobioisosteres of Curcumin with Pronounced Activity against Amyloid Aggregation, Intracellular Oxidative Stress, and Neuroinflammation
Hofmann, Julian,Ginex, Tiziana,Espargaró, Alba,Scheiner, Matthias,Gunesch, Sandra,Aragó, Marc,Stigloher, Christian,Sabaté, Raimon,Luque, F. Javier,Decker, Michael
, p. 6015 - 6027 (2021/03/16)
Many (poly-)phenolic natural products, for example, curcumin and taxifolin, have been studied for their activity against specific hallmarks of neurodegeneration, such as amyloid-β 42 (Aβ42) aggregation and neuroinflammation. Due to their drawbacks, arising from poor pharmacokinetics, rapid metabolism, and even instability in aqueous medium, the biological activity of azobenzene compounds carrying a pharmacophoric catechol group, which have been designed as bioisoteres of curcumin has been examined. Molecular simulations reveal the ability of these compounds to form a hydrophobic cluster with Aβ42, which adopts different folds, affecting the propensity to populate fibril-like conformations. Furthermore, the curcumin bioisosteres exceeded the parent compound in activity against Aβ42 aggregation inhibition, glutamate-induced intracellular oxidative stress in HT22 cells, and neuroinflammation in microglial BV-2 cells. The most active compound prevented apoptosis of HT22 cells at a concentration of 2.5 μm (83 % cell survival), whereas curcumin only showed very low protection at 10 μm (21 % cell survival).
Rhodium(III)-catalyzed regioselective C–H nitrosation/annulation of unsymmetrical azobenzenes to synthesize benzotriazole N-oxides via a RhIII/RhIII redox-neutral pathway
Zhang, Yuanfei,Chen, Zhe-Ning,Su, Weiping
supporting information, (2021/05/19)
A Rh(III)-catalyzed regioselective C–H nitrosation/annulation reaction of unsymmetrical azobenzenes with [NO][BF4] has been developed to achieve high-yielding syntheses of benzotriazole N-oxides with excellent functional group tolerance. Computational studies have revealed that this oxidative C–H functionalization reaction involves an interesting redox-neutral Rh(III)/Rh(III) pathway without the change of Rh oxidation state.
