348-54-9Relevant academic research and scientific papers
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.
Photocatalytic hydrogenation of nitroarenes: supporting effect of CoOx on TiO2 nanoparticles
Amanchi, Srinivasa Rao,Ashok Kumar,Lakshminarayana, Bhairi,Satyanarayana,Subrahmanyam
, p. 748 - 754 (2019)
Cobalt oxide visible light-active photo-catalysts supported on TiO2 nanoparticles with varying amount of cobalt oxide [3% CoOx/TiO2 (A), 4% CoOx/TiO2 (B), 5% CoOx/TiO2 (C)] were synthesized by solid-state method followed by calcination. The as-synthesized catalysts were characterized by various techniques such as powder XRD, TEM, EDX, UV-Vis-DRS and XPS analysis. The photocatalytic activity of the as-synthesized materials was studied for the reduction of nitroarenes to the corresponding amines using hydrazine monohydrate as the reductant. Cobalt(ii) oxide is responsible for the reduction of nitroarenes and then, cobalt(iii) is reduced back to the original compound by hydrazine hydrate, thus ascertaining the catalytic nature of this hydrogenation process. XPS suggests the presence of Co(ii) in CoOx/TiO2.
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.
Aminal-based Hypercrosslinked Polymer Modified with Small Palladium Nanoparticles for Efficiently Catalytic Reduction of Nitroarenes
Xu, Dan,Wang, Fushan,Yu, Guiqin,Zhao, Hong,Yang, Jing,Yuan, Man,Zhang, Xiaoyun,Dong, Zhengping
, p. 4569 - 4577 (2018)
Fabrication of heterogeneous catalysts with excellent activity, selectivity and stability is significant for various catalytic applications. Here, we prepared a hypercrosslinked polymer (HCP) via a facile and cost-effective strategy using ferrocenecarboxaldehyde and melamine as building blocks. Then, the HCP was modified with highly dispersed ultrafine Pd nanoparticles (Pd/HCP). The obtained Pd/HCP shows excellent catalytic activity in the catalytic reduction of nitroarenes under mild reaction conditions. It′s worth mentioning that the N atoms in the HCP can efficiently coordinate Pd ions to form small Pd nanoparticles (NPs) and subsequently prevent the aggregation and leaching of Pd NPs during the reaction, so the Pd/HCP catalyst is highly stable and can be reused at least eight cycles without loss of catalytic activity. Therefore, this work may provide possibilities for using HCPs as ideal supporting materials for fabricating highly stable and efficient heterogeneous catalysts.
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.
Highly selective hydrogenation of halonitroaromatics to aromatic haloamines by ligand modified Ni-based catalysts
Lu, Chun Shan,Lv, Jing Hui,Ma, Lei,Zhang, Qun Feng,Feng, Feng,Li, Xiao Nian
, p. 545 - 548 (2012)
Ligand modification of Ni-based catalysts by coordination of dicyandiamide to Ni metal leads to enhanced selectivity for the selective hydrogenation of halonitroaromatics. The selectivity of above 99.9% to aromatic haloamines can be achieved at the conversion of 100%. The results of H2-TPD and FT-IR experiments show that Ni-H+ species possessing the properties of Lewis acid site on the surface of Raney Ni could be responsible for the hydrodehalogenation. When Raney Ni was treated by dicyandiamide, Ni -H+ species interacted with N atom from the dicyandiamide. This interaction was stable even at reaction temperature, which reduced the possibility to form the intermediate state of ArCl?H+Ni -. And then CCl bond could not be polarized and activated. The hydrodechlorination process was suppressed effectively.
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.
Synthesis of Pt nanocatalysts for selective hydrogenation of ortho-halogenated nitrobenzene
Xie, Ruigang,Cao, Xueqin,Pan, Yue,Gu, Hongwei
, p. 1051 - 1055 (2015)
Monodisperse Pt nanoparticles (NPs) were prepared by reduction of platinum acetylacetonate in octadecene with the presence of Fe(CO)5. The synthesized nanocatalysts presented high activity and selectively for hydrogenation of ortho-halogenated nitrobenzene to the corresponding ortho-halogenated aniline under mild reaction conditions.
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.
Ligand compound for copper catalyzed aryl halide coupling reaction, catalytic system and coupling reaction
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Paragraph 0111-0119, (2021/05/29)
The invention provides a ligand compound capable of being used for copper catalyzed aryl halide coupling reaction, the ligand compound is a three-class compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group, and the invention also provides a catalytic system for the aryl halide coupling reaction. Thecatalytic system comprises a copper catalyst, a compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group adopted as a ligand, alkali and a solvent, and meanwhile, the invention also provides a system for the aryl halide coupling reaction adopting the catalyst system. The compound containing the 2-(substituted or non-substituted) aminopyridine nitrogen oxygen group can be used as the ligand for the copper catalyzed aryl chloride coupling reaction, and the ligand is stable under a strong alkaline condition and can well maintain catalytic activity when being used for the copper-catalyzed aryl chloride coupling reaction. In addition, the copper catalyst adopting the compound as the ligand can particularly effectively promote coupling of copper catalyzed aryl chloride and various nucleophilic reagents which are difficult to generate under conventional conditions, C-N, C-O and C-S bonds are generated, and numerous useful small molecule compounds are synthesized. Therefore, the aryl halide coupling reaction has a very good large-scale application prospect by adopting the copper catalysis system of the ligand.
