348-54-9Relevant articles and documents
Synthesis of Pd/SBA-15 catalyst employing surface-bonded vinyl as a reductant and its application in the hydrogenation of nitroarenes
Duan, Ying,Zheng, Min,Li, Dongmi,Deng, Dongsheng,Wu, Cuicui,Yang, Yanliang
, p. 3443 - 3449 (2017)
The Pd/SBA-15 catalyst was synthesised through the reduction of PdCl2 by the surface-bonded vinyl group on vinyl-functionalized SBA-15, which was prepared via co-polymerization. XRD and XPS characterization confirmed the successful reduction of Pd(ii) to Pd(0). Pd/SBA-15 showed a narrow palladium particle-size distribution of about 5-6 nm in the TEM image. The Pd/SBA-15 catalyst was effective for the hydrogenation of aromatic nitro compounds with zero-order kinetics, and the TOF for the hydrogenation of nitrobenzene was 1124 h-1 at 313 K and 1 atm H2. A steric effect was observed for the substituted nitroarenes.
Role of Charge Transfer in Nucleophilic Substitution Reactions in Clusters of 1-Fluoro-n-chlorobenzene Cations with Ammonia Molecules
Riehn, C.,Lahmann, C.,Brutschy, B.
, p. 3626 - 3632 (1992)
The reaction behavior of mixed clusters consisting of fluorochlorobenzene radical cations surrounded by ammonia molecules has been studied by resonant two-photon ionization.The spectral characterization of the neutral precursors allows one to study ion reactions in the cluster with a well-defined microsolvation environment.In addition to charge transfer, two types of nucleophilic substitution reactions take place.In a binary complex chlorine is ejected either in an ipso substitution by radical loss or, for meta and para isomers, by HCl formation, in the latter case by a metastable decay.The reaction efficiency for Cl elimination decreases with decreasing dipole moment of the chromophore.It is rationalized by a ? addition intermediate with an activation barrier due to charge transfer as postulated by the model of Shaik and Pross.The HCl elimination is not rate determined by the formation of a ? intermediate.In ternary and larger mixed complexes mainly substitution of fluorine takes place with HF as leaving group, corresponding to the onset of solvation catalysis.
A Radical-Mediated Approach to the Total Synthesis of Fluorinated Marinoquinoline A and Related Tricyclic and Tetracyclic Congeners
Patel, Bhaven,Hilton, Stephen T.
, p. 79 - 83 (2015)
A radical-mediated approach to the core structure of fluorinated marinoquinoline A, N-methylated marinoquinoline A and related congeners via the use of Togni's reagent is described.
PVA-encapsulated Palladium Nanoparticles: Eco-friendly and Highly Selective Catalyst for Hydrogenation of Nitrobenzene in Aqueous Medium
Wang, Xiaoyan,Huang, Changru,Li, Xiaohao,Xie, Congxia,Yu, Shitao
, p. 2266 - 2272 (2019)
In aqueous medium without any other additives, palladium (Pd) nanoparticles with water-soluble polyvinyl alcohol (PVA) as stabilizer were synthesized for the catalytic hydrogenation of nitrobenzene. Under the optimum experimental conditions, the nitrobenzene conversion and the selectivity for aniline were 99.3 % and 100 %, respectively. Comprehensive characterization methods, including TEM, UV/Vis, confocal laser scanning microscopy (CLSM), XRD and XPS allowed a better understanding of the role of PVA aggregates and the properties of Pd nanoparticles. The nitrobenzene conversion exceeded 80 % even after 6 cycles without any treatment of the catalyst. A mechanism about the hydrogenation of nitrobenzene catalyzed by Pd/PVA system was proposed. The Pd/PVA catalyst also exhibited excellent activity and selectivity, particularly to ortho-fluoronitrobenzene and ortho-nitrotoluene. This research can provide a reference for the environmentally friendly catalysis for hydrogenation of nitrobenzene and other substituted nitrobenzene compounds.
In situcreation of multi-metallic species inside porous silicate materials with tunable catalytic properties
Liu, Yang-Yang,Wu, Chuan-De,Zhan, Guo-Peng
supporting information, p. 6185 - 6188 (2021/06/30)
Porous metal silicate (PMS) material PMS-11, consisting of uniformly distributed multi-metallic species inside the pores, is synthesized by using a discrete multi-metal coordination complex as the template, demonstrating high catalytic activity and selectivity in hydrogenation of halogenated nitrobenzenes by synergistically activating different reactant moleculesviaNi and Co transition metal centers, while GdIIILewis acid sites play a role in tuning the catalytic properties.
Cobalt nanoclusters coated with N-doped carbon for chemoselective nitroarene hydrogenation and tandem reactions in water
Agostini, Giovanni,Calvino, Jose. J.,Corma, Avelino,Gutiérrez-Tarri?o, Silvia,Lopes, Christian W.,O?a-Burgos, Pascual,Rojas-Buzo, Sergio
supporting information, p. 4490 - 4501 (2021/06/28)
The development of active and selective non-noble metal-based catalysts for the chemoselective reduction of nitro compounds in aquo media under mild conditions is an attractive research area. Herein, the synthesis of subnanometric and stable cobalt nanoclusters, covered by N-doped carbon layers as core-shell (Co@NC-800), for the chemoselective reduction of nitroarenes is reported. TheCo@NC-800catalyst was prepared by the pyrolysis of the Co(tpy)2complex impregnated on Vulcan carbon. In fact, the use of a molecular complex based on six N-Co bonds drives the formation of a well-defined and distributed cobalt core-shell nanocluster covered by N-doped carbon layers. In order to elucidate its nature, it has been fully characterized by using several advanced techniques. In addition, this as-prepared catalyst showed high activity, chemoselectivity and stability toward the reduction of nitro compounds with H2and under mild reaction conditions; water was used as a green solvent, improving the previous results based on cobalt catalysts. Moreover, theCo@NC-800catalyst is also active and selective for the one-pot synthesis of secondary aryl amines and isoindolinones through the reductive amination of nitroarenes. Finally, based on diffraction and spectroscopic studies, metallic cobalt nanoclusters with surface CoNxpatches have been proposed as the active phase in theCo@NC-800material.
Sensitization-initiated electron transferviaupconversion: mechanism and photocatalytic applications
Glaser, Felix,Kerzig, Christoph,Wenger, Oliver S.
, p. 9922 - 9933 (2021/08/04)
Sensitization-initiated electron transfer (SenI-ET) describes a recently discovered photoredox strategy that relies on two consecutive light absorption events, triggering a sequence of energy and electron transfer steps. The cumulative energy input from two visible photons gives access to thermodynamically demanding reactions, which would be unattainable by single excitation with visible light. For this reason, SenI-ET has become a very useful strategy in synthetic photochemistry, but the mechanism has been difficult to clarify due to its complexity. We demonstrate that SenI-ET can operateviasensitized triplet-triplet annihilation upconversion, and we provide the first direct spectroscopic evidence for the catalytically active species. In our system comprised offac-[Ir(ppy)3] as a light absorber, 2,7-di-tert-butylpyrene as an annihilator, andN,N-dimethylaniline as a sacrificial reductant, all photochemical reaction steps proceed with remarkable rates and efficiencies, and this system is furthermore suitable for photocatalytic aryl dehalogenations, pinacol couplings and detosylation reactions. The insights presented here are relevant for the further rational development of photoredox processes based on multi-photon excitation, and they could have important implications in the greater contexts of synthetic photochemistry and solar energy conversion.
