496-16-2Relevant articles and documents
Stereoselective cyclizations mediated by functionalized organomagnesium reagents and catalyzed by cobalt or copper salts
Kneisel, Florian F.,Monguchi, Yasunari,Knapp, Kolja M.,Zipse, Hendrik,Knochel, Paul
, p. 4875 - 4879 (2002)
The iodine-magnesium exchange reaction with i-PrMgCl allows a mild preparation of functionalized arylmagnesium compounds bearing a leaving group in the molecule. With the appropriate transition-metal catalyst (a copper or cobalt salt), cyclization reactions occur leading to five- or six-membered ring systems in good yields.
A Novel Cyclodehydration Reaction of Hydroxy-phenols using Imidate Esters as Leaving Groups
Procopiou, Panayiotis A.,Brodie, Alastair C.,Deal, Martyn J.,Hayman, David F.
, p. 7483 - 7486 (1993)
A mild, efficient and stereospecific intramolecular method for converting hydroxy-phenols into benzodioxans, dihydrobenzopyrans and dihydrobenzofurans via imidate esters, and suitable for large scale operation is described.
A novel catalyst Pd@ompg-C3N4 for highly chemoselective hydrogenation of quinoline under mild conditions
Gong, Yutong,Zhang, Pengfei,Xu, Xuan,Li, Yi,Li, Haoran,Wang, Yong
, p. 272 - 280 (2013)
Polymeric mesoporous carbon graphitic nitrides (mpg-C3N 4) and ordered mesoporous graphitic carbon nitrides (ompg-C 3N4) with different surface area and morphology were used to prepare palladium catalysts (Pd@C3N4) by an easy ultrasonic-assisted method. These catalysts demonstrated excellent activity and selectivity for hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline under mild temperature (30-50 °C) and H2 pressure (1 bar). Pd@ompg-C3N4(r = 2.5) showed the best catalytic performance and both the activity and selectivity could be maintained for at least six reaction runs. The introduction of ordered cylindrical mesoporous structure and high concentration of surface Pd0 (about 70%) contribute to the high reaction activity and selectivity over Pd@ompg-C 3N4 catalysts.
Preparation of NiCu Alloy Catalyst for the Hydrodeoxygenation of Benzofuran
Zhu, Tianhan,Song, Hua,Li, Feng,Chen, Yanguang
, p. 1670 - 1682 (2020/10/21)
A series of bimetallic NixCu(10-x)/SiO2 (where x is the mass fraction of Ni and the total metal loading was fixed at 10 wt%.) catalysts with different Ni/Cu mass ratio are prepared and characterized by X-Ray diffraction (XRD), N2 adsorption-desorption, inductively coupled plasma mass spectrometry (ICP-MS), H2 temperature-programmed reduction (H2-TPR) and transmission electron microscope (TEM). The benzofuran (BF) hydrodeoxygenation (HDO) performance of as-prepared catalysts are evaluated in a fixed flow reactor. The results showed that the incorporation of Cu to Ni/SiO2 catalyst can increase surface area of catalyst and improve the reducibility of nickel oxide species, which contributed to higher catalytic activity and total deoxygenated compounds yield. Moreover, the strong synergistic effect between Ni and Cu led to the formation of NiCu alloy at the Ni mass fraction of 5 wt% and thus induced smaller crystallite size and exposure of more active particles, which inevitably contributed to the improved HDO performance for Ni5Cu5/SiO2 catalyst. At 300 °C, 3.0 MPa, MHSV=3.0 h?1 and H2/oil = 500(v/v), the total yield of deoxygenated products over Ni5Cu5/SiO2 catalyst reached 86.0%, which is increased by 10.8% and 77.4% as compared to those of monometallic Ni/SiO2 (75.2%) and Cu/SiO2 catalysts (8.8%), respectively. Finally, a possible reaction network for HDO of BF on Ni5Cu5/SiO2 catalyst was proposed. Graphic Abstract: [Figure not available: see fulltext.]
Organometallic Synthesis of Bimetallic Cobalt-Rhodium Nanoparticles in Supported Ionic Liquid Phases (CoxRh100?x@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates
Rengshausen, Simon,Van Stappen, Casey,Levin, Natalia,Tricard, Simon,Luska, Kylie L.,DeBeer, Serena,Chaudret, Bruno,Bordet, Alexis,Leitner, Walter
, (2020/12/22)
The synthesis, characterization, and catalytic properties of bimetallic cobalt-rhodium nanoparticles of defined Co:Rh ratios immobilized in an imidazolium-based supported ionic liquid phase (CoxRh100?x@SILP) are described. Following an organometallic approach, precise control of the Co:Rh ratios is accomplished. Electron microscopy and X-ray absorption spectroscopy confirm the formation of small, well-dispersed, and homogeneously alloyed zero-valent bimetallic nanoparticles in all investigated materials. Benzylideneacetone and various bicyclic heteroaromatics are used as chemical probes to investigate the hydrogenation performances of the CoxRh100?x@SILP materials. The Co:Rh ratio of the nanoparticles is found to have a critical influence on observed activity and selectivity, with clear synergistic effects arising from the combination of the noble metal and its 3d congener. In particular, the ability of CoxRh100?x@SILP catalysts to hydrogenate 6-membered aromatic rings is found to experience a remarkable sharp switch in a narrow composition range between Co25Rh75 (full ring hydrogenation) and Co30Rh70 (no ring hydrogenation).
Heterogeneous Hydrogenation of Quinoline Derivatives Effected by a Granular Cobalt Catalyst
Timelthaler, Daniel,Topf, Christoph
, (2021/11/22)
We communicate a convenient method for the pressure hydrogenation of quinolines in aqueous solution by using a particulate cobalt-based catalyst that is prepared in situ from simple Co(OAc)2 4H2O through reduction with abundant zinc powder. This catalytic protocol permits a brisk and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines thereby relying solely on easy-to-handle reagents that are all readily obtained from commercial sources. Both the reaction setup assembly and the autoclave charging procedure are conducted on the bench outside an inert-gas-operated containment system, thus rendering the overall synthesis time-saving and operationally very simple.
Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
, p. 2909 - 2915 (2021/03/14)
The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
Synthesis of Ni2P/Al2O3 utilizing triphenylphosphine (TPP) as the phosphorus source for hydrodeoxygenation of benzofuran
Jiang, Bolong,Jiang, Nan,Han, Chunbao
, p. 7577 - 7582 (2020/06/19)
A novel route to synthesize highly active Ni2P/Al2O3 (TPP) utilizing triphenylphosphine (TPP) as the phosphorus source at a low temperature of 573 K is described. The as-prepared catalysts were characterized by X-ray diffraction (XRD), CO uptake, Brunner-Emmett-Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the Ni2P/Al2O3 (TPP) catalyst and the role of the TPP phosphorus source were studied using hydrodeoxygenation (HDO) of benzofuran (BF) as a probe reaction. The results show that the use of TPP as the phosphorus source could suppress the strong interaction between phosphate and Al2O3, thereby the formation of AlPO4 was avoided. As compared to the Ni2P/Al2O3 prepared by using (NH4)2HPO4 as the phosphorus source, Ni2P/Al2O3 (TPP) possessed significantly higher surface area and smaller Ni2P particle size. The HDO activity and yield of O-free products over the Ni2P/Al2O3 (TPP) catalyst were increased by 17.2% and 36.0%, respectively, when compared with those found for Ni2P/Al2O3 prepared using (NH4)2HPO4. The use of TPP as the phosphorus source could effectively promote the dehydration of 2-ethylphenol (2-EtPh) to form ethylbenzene (EB), and the demethylation of ethylcyclohexane (ECH) to methylcyclohexane (MCH).
Light-Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII-Aryl Complex
Cao, Rui,Lai, Chu-Hui,Li, Gang,Liu, Fengyi,Lu, Huan-Huan,Wang, Chao,Xiao, Jianliang,Xue, Dong,Yang, Liu,Zhang, Wei
supporting information, p. 12714 - 12719 (2020/06/02)
A highly effective C?O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C?O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle.
Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
supporting information, p. 4119 - 4129 (2020/08/10)
A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
