1453-24-3Relevant academic research and scientific papers
Investigation of the reaction network of benzofuran hydrodeoxygenation over sulfided and reduced Ni-Mo/Al2O3 catalysts
Ozkan,Bunch
, p. 177 - 187 (2002)
The hydrodeoxygenation (HDO) network of benzofuran was studied over alumina-supported Ni-Mo sulfided and reduced catalysts. Over the sulfided catalyst, a major route was observed for the benzofuran HDO network. It started with the hydrogenation of benzofuran to 2,3-dihydrobenzofuran followed by its hydrogenolysis to 2-ethylphenol. However, over the reduced catalysts, an additional route was observed which begins with the hydrogenation of 2,3-dihydrobenzofuran. This route contained a number of other oxygen-containing intermediate species which were not observed over the sulfided catalyst, and hydrocarbon products were formed by this route at significantly lower temperatures. The product distribution for both catalysts was a strong function of temperature and H2S feed concentration where the hydrogenolysis reactions were promoted and the hydrogenation reactions were inhibited by H2S in the feedstream.
Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
, p. 3685 - 3690 (2021/05/31)
Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
ISOMERIZATION OF ALKENES
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Page/Page column 20-21; 25, (2020/04/25)
The present invention relates to an isomerization method for alkenes, comprising of reaction an alkene with a Ni(I)-compound. By this method, E-Alkenes are obtained in excellent yield.
Regioselective Isomerization of Terminal Alkenes Catalyzed by a PC(sp3)Pincer Complex with a Hemilabile Pendant Arm
De-Botton, Sophie,Filippov, D.Sc. Oleg A.,Shubina, Elena S.,Belkova, Natalia V.,Gelman, Dmitri
, p. 5959 - 5965 (2020/10/15)
We describe an efficient protocol for the regioselective isomerization of terminal alkenes employing a previously described bifunctional Ir-based PC(sp3)complex (4) possessing a hemilabile sidearm. The isomerization, catalyzed by 4, results in a one-step shift of the double bond in good to excellent selectivity, and good yield. Our mechanistic studies revealed that the reaction is driven by the stepwise migratory insertion of Ir?H species into the terminal double bond/β-H elimination events. However, the selectivity of the reaction is controlled by dissociation of the hemilabile sidearm, which acts as a selector, favoring less sterically hindered substrates such as terminal alkenes; importantly, it prevents recombination and further isomerization of the internal ones.
A nickel-iridium alloy as an efficient heterogeneous catalyst for hydrogenation of olefins
Bai, Jia-qi,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
supporting information, p. 10519 - 10522 (2019/09/06)
Nickel and iridium supported on SiO2 (Ni-Ir/SiO2) acted as an effective and reusable heterogeneous catalyst for hydrogenation of olefins, and it showed higher activity and selectivity than the monometallic counterparts. The Ni-Ir/SiO2 catalyst has small Ni-Ir alloy and monometallic Ni particles, and the high catalytic performance can be attributed to the isolated Ni atom in the Ni-Ir alloys.
E-Olefins through intramolecular radical relocation
Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
, p. 391 - 396 (2019/02/03)
Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
Trans -2 - substituted cycloalkyl three fluoro potassium borate synthesis method (by machine translation)
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Paragraph 0022, (2019/04/04)
The invention discloses trans - 2 - substituted cyclohexyl three fluoro potassium borate synthesis method, which belongs to the field of organic synthesis. From the cyclic ketone starting curing and reagent or lithium reagent addition subsequently dehydrated and gets substituted alkenes, subsequently with the catechol borane or after aminol borane addition reaction, fluorine hydride potassium direct quenching treatment to obtain trans - 2 - substituted cyclohexyl three fluoro potassium borate, the catechol borane to obtain the racemate product, [...] photoinitiators enantiomerically pure product. The method has low cost, convenient source of raw materials, the operation is simple, and has industrial amplifying of the prospect. (by machine translation)
Cross-Linked "poisonous" Polymer: Thermochemically Stable Catalyst Support for Tuning Chemoselectivity
Yun, Seongho,Lee, Songhyun,Yook, Sunwoo,Patel, Hasmukh A.,Yavuz, Cafer T.,Choi, Minkee
, p. 2435 - 2442 (2016/04/26)
Designed catalyst poisons can be deliberately added in various reactions for tuning chemoselectivity. In general, the poisons are "transient" selectivity modifiers that are readily leached out during reactions and thus should be continuously fed to maintain the selectivity. In this work, we supported Pd catalysts on a thermochemically stable cross-linked polymer containing diphenyl sulfide linkages, which can simultaneously act as a catalyst support and a "permanent" selectivity modifier. The entire surfaces of the Pd clusters were ligated (or poisoned) by sulfide groups of the polymer support. The sulfide groups capping the Pd surface behaved like a "molecular gate" that enabled exceptionally discriminative adsorption of alkynes over alkenes. H2/D2 isotope exchange revealed that the capped Pd surface alone is inactive for H2 (or D2) dissociation, but in the presence of coflowing acetylene (alkyne), it becomes active for H2 dissociation as well as acetylene hydrogenation. The results indicated that acetylene adsorbs on the Pd surface and enables cooperative adsorption of H2. In contrast, ethylene (alkene) did not facilitate H2-D2 exchange, and hydrogenation of ethylene was not observed. The results indicated that alkynes can induce decapping of the sulfide groups from the Pd surface, while alkenes with weaker adsorption strength cannot. The discriminative adsorption of alkynes over alkenes led to highly chemoselective hydrogenation of various alkynes to alkenes with minimal overhydrogenation and the conversion of side functional groups. The catalytic functions can be retained over a long reaction period due to the high thermochemical stability of the polymer.
Z -selective alkene isomerization by high-spin cobalt(II) complexes
Chen, Chi,Dugan, Thomas R.,Brennessel, William W.,Weix, Daniel J.,Holland, Patrick L.
supporting information, p. 945 - 955 (2014/02/14)
The isomerization of simple terminal alkenes to internal isomers with Z-stereochemistry is rare, because the more stable E-isomers are typically formed. We show here that cobalt(II) catalysts supported by bulky β-diketiminate ligands have the appropriate kinetic selectivity to catalyze the isomerization of some simple 1-alkenes specifically to the 2-alkene as the less stable Z-isomer. The catalysis proceeds via an "alkyl" mechanism, with a three-coordinate cobalt(II) alkyl complex as the resting state. β-Hydride elimination and [1,2]-insertion steps are both rapid, as shown by isotopic labeling experiments. A steric model explains the selectivity through a square-planar geometry at cobalt(II) in the transition state for β-hydride elimination. The catalyst works not only with simple alkenes, but also with homoallyl silanes, ketals, and silyl ethers. Isolation of cobalt(I) or cobalt(II) products from reactions with poor substrates suggests that the key catalyst decomposition pathways are bimolecular, and lowering the catalyst concentration often improves the selectivity. In addition to a potentially useful, selective transformation, these studies provide a mechanistic understanding for catalytic alkene isomerization by high-spin cobalt complexes, and demonstrate the effectiveness of steric bulk in controlling the stereoselectivity of alkene formation.
Ligand effect in the Rh-NP catalysed partial hydrogenation of substituted arenes
Castelbou, Jessica Llop,Gual, Aitor,Mercade, Elisabet,Claver, Carmen,Godard, Cyril
, p. 2828 - 2833 (2013/09/24)
The Rh nanoparticles Rh1-Rh4 stabilised by the mono- and bidentate phosphine and phosphite ligands I-IV were synthesised, characterised and applied as catalysts in the partial hydrogenation of substituted arenes. In the case of disubstituted arenes, selectivities for the corresponding cyclohexene derivatives of up to 39% were achieved at ca. 40% conversion. The effect of parameters such as temperature and pressure was also examined. In the hydrogenation of styrene, very high selectivities for ethylbenzene were achieved with TOF values up to ca. 23500 h-1. All these results show that the catalytic performance of small Rh-NPs can be modulated by the appropriate choice of stabilising agents.
