- Selective hydroisomerization of n-dodecane over platinum supported on zeolites
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In this study, in order to develop catalysts for the selective isomerization of higher paraffin, the hydroisomerization reaction of n-dodecane was performed as a model reaction. Pt/ZSM-48, Pt/HZSM-5, Pt/HY, and Pt/SAPO-11 were examined for the selective hydroisomerization of n-dodecane. The catalysts were characterized via X-ray powder diffraction, N2 adsorption, and the temperature-programmed desorption of ammonia. Among the catalysts studied, the Pt/HZSM-48 catalyst exhibited the best isomerization selectivity in the hydroisomerization reaction of n-dodecane, which is attributed to the moderate acid sites and medium-sized pores present in the HZSM-48. The highest iso-dodecane yield was obtained at a reaction temperature of 280 °C in the Pt/HZSM-48 catalyst. The optimal selectivity of the n-dodecane hydroisomerization over the Pt/SAPO-11 catalyst was obtained at approximately 300 °C, which was slightly higher than that of the Pt/HZSM-48 catalyst.
- Yun, Soyoung,Lee, Eunok,Park, Young-Kwon,Jeong, Soon-Yong,Han, Jeongsik,Jeong, Byunghun,Jeon, Jong-Ki
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- Hydroconversion of n-dodecane over nanoporous catalysts
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Platinum catalysts impregnated on different nanoporous materials, Meso-MFI, Si-SBA-15 and Al-SBA-15, were synthesized, and the hydroconversion of n-dodecane over these catalysts was performed. The catalytic characteristics were analyzed by Brunauer-Emmett-Teller surface area, X-ray diffraction, N 2-adsorption-desorption and temperature programmed desorption of NH3. The effects of operation parameters, such as temperature and pressure, on the catalytic activities were investigated. The catalytic activities were affected considerably by the acidic properties of the catalysts, temperature and pressure. Higher acidity, high temperature and low hydrogen pressure resulted in higher hydroconversion and facilitated hydrocracking. The weak acidity, low temperature and high hydrogen pressure resulted in lower hydroconversion and higher selectivity to i-dodecane. Copyright
- Park, Young-Kwon,Lee, Hyung Won,Jeon, Jong-Ki,Han, Jeongsik,Kim, Chul-Ung,Jeong, Soon-Yong,Jeong, Kwang-Eun
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- AIR-STABLE NI(0)-OLEFIN COMPLEXES AND THEIR USE AS CATALYSTS OR PRECATALYSTS
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The present invention relates to air stable, binary Ni(0)-olefin complexes and their use in organic synthesis.
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Page/Page column 20-21
(2021/02/05)
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- Mechanistic Insight into Synergistic Catalysis of Olefin Hydrogenation by a Hetero-Dinuclear RuII-CoII Complex with Adjacent Reaction Sites
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We have designed and synthesized a hetero-dinuclear RuII-CoII complex with a dinucleating ligand inspired by hetero-dinuclear active sites of metalloenzymes. A synergistic effect between the adjacent RuII and CoII sites has been confirmed in catalytic olefin hydrogenation by the complex, exhibiting a much higher turnover number than those of mononuclear RuII or CoII complexes as the components. A RuII-hydrido species was detected by 1H NMR and electrospray ionization (ESI)-time-of-flight (TOF)-MS measurements as an intermediate to react with olefins, and CoII-bound methanol was suggested to act as a proton source.
- Hong, Dachao,Ohgomori, Yuji,Shimoyama, Yoshihiro,Kotani, Hiroaki,Ishizuka, Tomoya,Kon, Yoshihiro,Kojima, Takahiko
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supporting information
p. 11284 - 11288
(2019/09/03)
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- Co-Catalyzed Cross-Coupling Reaction of Alkyl Fluorides with Alkyl Grignard Reagents
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The cross-coupling reaction of unactivated alkyl fluorides with alkyl Grignard reagents by a CoCl2/LiI/1,3-pentadiene catalytic system is described. The present reaction smoothly cleaved C-F bonds under mild conditions and achieved alkyl-alkyl cross-coupling even when sterically hindered tertiary alkyl Grignard reagents were employed. Since alkyl fluorides are inert toward many reagents and catalytic intermediates, the use of the present reaction enables a new multistep synthetic route to construct carbon frameworks by combining conventional transformations.
- Iwasaki, Takanori,Yamashita, Koji,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 3691 - 3694
(2017/07/26)
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- One-step Pd/C and Eu(OTf)3 catalyzed hydrodeoxygenation of branched C11 and C12 biomass-based furans to the corresponding alkanes
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Solvent-free NaOH catalyzed aldol condensation of biomass-derived 5-hydroxymethyl furfural (HMF) and furfural with methyl isobutyl ketone (MIBK) was studied, producing branched C11and C12furan compounds in high yields of up to 96%. Through use of a Pd/C and Eu(OTf)3catalytic system, the condensation products of the bio-based starting materials were further hydrodeoxygenated (HDO) in one-step to biofuel compatible branched alkanes 2-methylundecane (3) and 2-methyldecane (4) in excellent yields of 90% and 98%, respectively. In the one-step HDO developed herein, the variation of solvent had a significant effect on the reaction route and degree of conversion of furans to alkanes in the HDO process. Very high overall yields of alkanes 3 (86%) and 4 (94%) were obtained starting from the biomass-based HMF and furfural.
- Keskiv?li, Juha,Wrigstedt, Pauli,Lagerblom, Kalle,Repo, Timo
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- Synthesis, characterization and isomerization performance of micro/mesoporous materials based on H-ZSM-22 zeolite
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Micro/mesoporous materials with different mesoporosities were prepared through recrystallization of H-ZSM-22 zeolite in alkaline solution with cetyltrimethylammonium bromide template (CTAB). The structure, morphology, pore properties, acidity and isomerization performance of the catalysts by using the resulting materials were characterized and assessed. The dissolution and recrystallization procedure introduced the well-developed mesoporous structure of MCM-41 type with the meso-scale channels of about 3 nm in size on the outer surfaces of the microporous H-ZSM-22 zeolites, forming the micro/mesoporous materials, which possessed increased weak B acid sites at the pore mouths and a reduced amount of total acid sites. It is shown that the presence of well-developed mesopores could remarkably improve the selectivity to multi-branched products and suppress the side cracking reactions in n-dodecane isomerization. The micro/mesoporous Pt/ZSM-22/MCM-41 bifunctional catalyst with suitable recrystallization degree exhibits high isomerization selectivity under high conversion in long-chain n-alkane isomerization compared to the original microporous Pt/H-ZSM-22 catalyst.
- Liu, Suyao,Ren, Jie,Zhang, Huaike,Lv, Enjing,Yang, Yong,Li, Yong-Wang
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- Mechanism of low-molecular alkenes interaction with sulfur-containing spatially hindered phenols under conditions of thermal modification of polymer materials
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Abstract Transformations in the course of high-temperature modification of polyolefins under action of sulfur-containing modifiers have been studied using hexene-1 and hexane as model compounds. Composition of products of thermolysis of bis[3-(3,5-di-tert
- Krysin,Pokrovskii,Nefedov,Shundrina,Selivanov
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p. 659 - 666
(2015/05/05)
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- The cobalt-catalyzed cross-coupling reaction of alkyl halides with alkyl Grignard reagents: A new route to constructing quaternary carbon centers
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The cross-coupling of alkyl (pseudo)halides with alkyl Grignard reagents is catalyzed efficiently by a cobalt(II) chloride-lithium iodide-1,3-diene catalytic system, which provides a new synthetic tool for constructing sp 3 carbon chains. This system is particularly useful for creating quaternary carbon centers via the use of tertiary alkyl Grignard reagents. Various functional groups including esters, amides and carbamates are well tolerated.
- Iwasaki, Takanori,Takagawa, Hiroaki,Okamoto, Kanako,Singh, Surya Prakash,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 1583 - 1592
(2014/06/23)
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- Cross-coupling of alkyl halides with aryl or alkyl Grignards catalyzed by dinuclear Ni(ii) complexes containing functionalized tripodal amine-pyrazolyl ligands
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Structurally distinctive dinuclear Ni(ii) complexes with furan or thiophene tethered amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. All complexes are catalytically active towards cross-coupling of aryl/alkyl Grignard reagents with β-H containing alkyl halides at room temperature in the presence of N,N,N',N'- tetramethylethylenediamine (TMEDA). The catalytic efficacy of the complexes is dependent on the tether substituent at the central amine. Two species, Ni(ii) TMEDA and Mg(ii) TMEDA complexes, have been isolated from the catalytic reaction mixtures under different conditions. Some ligand-stabilized Ni(ii) and Mg(ii) bimetallic species have also been identified in the ESI-MS spectra.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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p. 5150 - 5158
(2013/04/10)
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- Co-catalyzed cross-coupling of alkyl halides with tertiary alkyl Grignard reagents using a 1,3-butadiene additive
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The cobalt-catalyzed cross-coupling of alkyl (pseudo)halides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor and LiI is described. Sterically congested quaternary carbon centers could be constructed by using tertiary alkyl Grignard reagents. This reaction proceeds via an ionic mechanism with inversion of stereochemistry at the reacting site of the alkyl halide and is compatible with various functional groups. The use of both 1,3-butadiene and LiI was essential for achieving high yields and high selectivities.
- Iwasaki, Takanori,Takagawa, Hiroaki,Singh, Surya P.,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 9604 - 9607
(2013/07/26)
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- Nickel complexes of a pincer amidobis(amine) ligand: Synthesis, structure, and activity in stoichiometric and catalytic C-C bond-forming reactions of alkyl halides
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The synthesis, properties, and reactivity of nickel(II) complexes of a newly developed pincer amidobis(amine) ligand (McNN2) are described. Neutral or cationic complexes [(MeNN2)NiX] (X = OTf (6), OC(O)CH3 (7), CH3CN (8), OMe (9)) were prepared by salt metathesis or chloride abstraction from the previously reported [( MeNN2)NiCl] (1). The Lewis acidity of the {( McNN2)Ni) fragment was measured by the 1H NMR chemical shift of the coordinated CH3CN molecule in 8. Electrochemical measurements on 1 and 8 indicate that the electron-donating properties of NN2 are similar to those of the analogous amidobis(phosphine) (pnp) ligands. The solid-state structures of 6-8 were determined and compared to those of 1 and [(MeNN2)NiEt] (3). In all complexes, the MeNN2 ligand coordinates to the NiII ion in a mer fashion, and the square-planar coordination sphere of the metal is completed by an additional donor. The coordination chemistry of MeNN 2 thus resembles that of other three-dentate pincer ligands, for example, pnp and arylbis(amine) (ncn). Reactions of 2 with alkyl monohalides, dichlorides, and trichlorides were investigated. Selective C-C bond formation was observed in many cases. Based on these reactions, efficient Kumada-Corriu-Tamao coupling of unactivated alkyl halides and alkyl Grignard reagents with 1 as the precatalyst was developed. Good yields were obtained for the coupling of primary and secondary iodides and bromides. Double C-C coupling of CH2Cl2 with alkyl Grignard reagents by 1 was also realized. The scope and limitations of these transformations were studied. Evidence was found for a radical pathway in Ni-catalyzed C-C cross-coupling reactions, which involves NiIl alkyl intermediates.
- Vechorkin, Oleg,Csok, Zsolt,Scopelliti, Rosario,Hu, Xile
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experimental part
p. 3889 - 3899
(2009/12/26)
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- Copper-catalyzed cross-coupling reaction of Grignard reagents with primary-alkyl halides: Remarkable effect of 1-phenylpropyne
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(Chemical Equation Presented) A general get-together: The Cu-catalyzed cross-coupling reaction of primary-alkyl halides with primary-, secondary-, and tertiary-alkyl and phenyl Grignard reagents proceeds efficiently in THF under reflux in the presence of 1-phenylpropyne (see scheme). The reaction is also applicable to alkyl mesylates (OMs) and tosylates (OTs). The reactivities of alkyl-X with a Grignard reagent increase in the order X = Cl F OMs OTs Br.
- Terao, Jun,Todo, Hirohisa,Begum, Shameem Ara,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 2086 - 2089
(2008/02/14)
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- Cross-Couplings of Unactivated Secondary Alkyl Halides: Room-Temperature Nickel-Catalyzed Negishi Reactions of Alkyl Bromides and Iodides
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The development of a nickel- or palladium-catalyzed method for cross-coupling unactivated secondary alkyl halides has been a long-standing challenge in synthetic chemistry. This communication describes a simple catalyst system-Ni(cod)2/s-Bu-Pybox-that achieves room-temperature Negishi reactions of an array of functionalized primary and secondary alkyl bromides and iodides. Copyright
- Zhou, Jianrong,Fu, Gregory C.
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p. 14726 - 14727
(2007/10/03)
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- Novel organomanganese(II) complexes active as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon-carbon bond formation reactions
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Novel organomanganese complexes 3 and 4 were prepared via transmetallation of the corresponding organolithium reagent. These new complexes are active catalysts in manganese/copper mediated cross-coupling reactions.
- Donkervoort, Johannes G.,Vicario, Jose L.,Jastrzebski, Johann T.B.H.,Cahiez, Gerard,Van Koten, Gerard
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p. 547 - 548
(2007/10/03)
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- REDUCTION OF THIIRANES TO ALKENES AND ALKANES
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Various reagents were tested in order to reduce thiiranes to alkanes or olefins.The results of this investigation is presented in this letter.
- Schauder, J.R.,Denis, J.N.,Krief, A.
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p. 1657 - 1660
(2007/10/02)
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