1515-95-3Relevant academic research and scientific papers
Volatile components of the liverworts Archilejeunea olivacea, Cheilolejeunea imbricata and Leptolejeunea elliptica
Toyota, Masao,Koyama, Hiroki,Asakawa, Yoshinori
, p. 1261 - 1264 (1997)
Three liverworts, Archilejeunea olivacea. Cheilolejeunea imbricata and Leptolejeunea elliptica, belonging to the Lejeuneaceae, have been investigated chemically. Olivacene, a new naturally occurring sesquiterpene hydrocarbon, β-monocyclonerolidol and (-)-spathulenol have been isolated from A. olivacea. The strong milky-like fragrance of C. imbricata is due to a mixture of (R)-dodec-2-en-1, 5-olide and (R)-tetradec-2-en-1,5-olide. Leptolejeunea elliptica produces an intensely fragrant odour which is due to a mixture of 1-ethyl-4-methoxy-, 1-ethyl-4-hydroxy- and 1-ethyl-4- acetoxybenene. There are no chemical affinities between the present three Lejeuneaceae species.
Preparation of Magnetic Tubular Nanoreactors for Highly Efficient Catalysis
Yang, Shuliang,Peng, Li,Cao, Changyan,Wei, Fang,Liu, Jian,Zhu, Ya-Nan,Liu, Chang,Wang, Xiaoshi,Song, Weiguo
, p. 2797 - 2801 (2016)
We report an efficient and controllable route to prepare magnetic tubular nanoreactors composed of a mesoporous SiO2 shell with iron-noble metal nanoparticles inside. The key of this method is to design and fabricate Fe nanoparticles encapsulated in a mesoporous SiO2 shell. Making use of a galvanic replacement reaction between Fe and noble metal ions, all of the noble metal nanoparticles are loaded inside the mesoporous SiO2 shell, and thus nanoreactors are formed. Taking Pd as an example, the prepared Pd?Fe@meso-SiO2 tubular nanoreactor exhibits a high catalytic activity and excellent reusability for styrene hydrogenation under mild conditions. This study provides a facile route to fabricate magnetic nanoreactors with enhanced catalytic properties.
Dehydrocoupling of dimethylamine-borane catalysed by rhenium complexes and its application in olefin transfer-hydrogenations
Jiang, Yanfeng,Berke, Heinz
, p. 3571 - 3573 (2007)
Re(I) complexes are applied as catalysts for the dehydrocoupling of Me 2NH·BH3 and the transfer-hydrogenation of olefins. The Royal Society of Chemistry.
Synthesis of Ruthenium Complexes with a Nonspectator Si,O,P-Chelate Ligand: Interconversion between a Hydrido(η2-silane) Complex and a Silyl Complex Leading to Catalytic Alkene Hydrogenation
Komuro, Takashi,Arai, Takafumi,Kikuchi, Kei,Tobita, Hiromi
, p. 1211 - 1217 (2015)
A ruthenium complex bearing a new phosphine(η2-silane) chelate ligand connected by a xanthene backbone, Ru{κ4(Si,H,O,P)-tBu2xantSiP(H)}(H)Cl(PPh3) (2), was synthesized by a ligand substitution reaction of Ru(H)Cl(PPh3)3 with 2,7-di-tert-butyl-4-dimethylsilyl-5-diphenylphosphino-9,9-dimethylxanthene (1, tBu2xantSiP(H)). Dehydrogenation reaction of 2 with styrene, a hydrogen acceptor, gave a 16-electron phosphine(silyl) complex Ru{κ3(Si,O,P)-tBu2xantSiP}Cl(PPh3) (3) together with ethylbenzene. Complex 2 was reproduced quantitatively by exposure of 3 to H2 (1 atm) at room temperature. Thus, hydrido(η2-silane) complex 2 and silyl complex 3 are interconvertible through alkene hydrogenation (from 2 to 3) and dihydrogen addition to the Ru-Si bond (from 3 to 2) in which tBu2xantSiP functions as a nonspectator ligand by reversibly releasing and accommodating a hydrogen atom. Complex 2 was also found to catalyze hydrogenation of alkenes via this interconversion. (Chemical Presented).
Nanoscale magnetic stirring bars for heterogeneous catalysis in microscopic systems
Yang, Shuliang,Cao, Changyan,Sun, Yongbin,Huang, Peipei,Wei, Fangfang,Song, Weiguo
, p. 2661 - 2664 (2015)
Nanometer-sized magnetic stirring bars containing Pd nanoparticles (denoted as Fe3O4-NC-PZS-Pd) for heterogeneous catalysis in microscopic system were prepared through a facile two-step process. In the hydrogenation of styrene, Fe3O4-NC-PZS-Pd showed an activity similar to that of the commercial Pd/C catalyst, but much better stability. In microscopic catalytic systems, Fe3O4-NC-PZS-Pd can effectively stir the reaction solution within microdrops to accelerate mass transfer, and displays far better catalytic activity than the commercial Pd/C for the hydrogenation of methylene blue in an array of microdroplets. These results suggested that the Fe3O4-NC-PZS-Pd could be used as nanoscale stirring bars in nanoreactors.
Iridium(I)/N-Heterocyclic Carbene Hybrid Materials: Surface Stabilization of Low-Valent Iridium Species for High Catalytic Hydrogenation Performance
Romanenko, Iuliia,Gajan, David,Sayah, Reine,Crozet, Delphine,Jeanneau, Erwan,Lucas, Christine,Leroux, Lénaic,Veyre, Laurent,Lesage, Anne,Emsley, Lyndon,Lac?te, Emmanuel,Thieuleux, Chloé
, p. 12937 - 12941 (2015)
An IrI(NHC)-based hybrid material was prepared using a methodology which allowed the precise positioning and isolation of the Ir centers along the pore channels of a silica framework. The full characterization of the material by solid-state NMR spectroscopy showed that the supported Ir sites were stabilized by the silica surface, as low-coordinated single-site complexes. The material is extremely efficient for the hydrogenation of functional alkenes. The catalytic performance (TOF and TON) is one to two orders of magnitude higher than those of their molecular Ir analogues, and could be related to the prevention of the bimolecular deactivation of Ir complexes observed under homogeneous conditions. Lending support: Homogeneous positioning of IrI complexes within the pore-channels of a silica framework stabilizes a low-valent IrI species and leads to drastically improved catalyst efficiency. Catalyst decomposition by formation of iridium-hydride clusters is prevented by the attachment to the support. Mes=2,4,6-trimethylphenyl.
Pd Nanoparticles Confined in the Porous Graphene-like Carbon Nanosheets for Olefin Hydrogenation
Chen, Zhe,Wang, Weixue,Zhang, Yifei,Liang, Yu,Cui, Zhimin,Wang, Xiangke
, p. 12809 - 12814 (2018)
As a novel type of defective graphene, porous graphene has been considered an excellent support material for metal clusters, as the interaction between defective carbon atoms surrounded with the metal nanoparticles (NPs) is very different from that on the ordinary supported catalyst. In this work, we reported a facile three-step method to confine the Pd NPs and grow the graphene-like carbon nanosheets (GLCs) in the same interlayer space of the layered silicate, generating embedded Pd NPs in the pores of porous GLCs in situ. The Pd@GLC nanocomposite exhibited not only high activity and stability than the common commercial Pd/C catalyst for the hydrogenation of olefins but also superior ability of resisting high temperature, which benefitted from the two-dimensional structure of layered GLCs, the confinement of Pd, and the increased edge and defect of the unsaturated carbon atoms in GLCs.
Selective hydrogenation of substituted styrene to alkylbenzene catalyzed by Al2O3 nanoparticles
Kaleeswari, Kalairajan,Tamil Selvi, Arunachalam
, (2022/01/22)
A straightforward and suitable protocol is described for the conversion of substituted styrene to alkylbenzenes in the presence of Al2O3 nanoparticles (nano-Al2O3) as heterogeneous solid catalysts using N2H4·H2O as a hydrogen source under mild reaction conditions. A complete conversion of styrene is obtained using nano-Al2O3 as a heterogeneous catalyst. Besides, this catalyst system is also successfully applied to promote the broad range of styrene substituted derivatives to their respective alkylbenzene compounds in moderate to higher conversions. The reaction is discovered to be heterogeneous in nature and nano-Al2O3 can be reused for three runs with no diminish in its performance. Besides, the analyses of the fresh and three times reused nano-Al2O3 solid by various analytical techniques. Transmission electron microscope indicates that the structural features, surface morphology, and particle size endure unchanged throughout the reaction. Some of the significant features of this procedure are mild reaction conditions, price effectiveness of the catalyst (Pd or Pt free catalyst), high conversion, functional group endurance, absence of noble metals/additives, and reusability of the catalyst. The scope of the reaction procedure can be extended to various linear and cyclic alkenes. Graphical abstract: [Figure not available: see fulltext.]
Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Newar, Rajashree,Rawat, Manhar Singh,Manna, Kuntal
supporting information, p. 1031 - 1040 (2022/01/19)
The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
