- ETUDE DE LA DIMERISATION DU PROPYLENE CATALYSEE EN PHASE HOMOGENE PAR DES ESPECES DU TYPE "HCoLx"
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The dimerisation of propylene in methylpentenes (60percent) at 25 deg C is catalysed by two active cobalt species.The first, HCoL3, issued from the system "Co(Acac)3/HAlEt2/L" in the presence of 1,5-cyclooctadiene, is more active (*30) and selective in 2-methyl-1-pentene (85percent of dimers) than the second, formed from HCo(COD)2.Under low pressures of propylene (3 bar), the fraction of higher oligomers (mainly trimers) increases only up to 40percent.
- Petit, F.,Masotti, H.,Peiffer, G.,Buono, G.
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Read Online
- Nickel Hydride Complexes Supported by a Pyrrole-Derived Phosphine Ligand
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The synthesis of two nickel hydride complexes bearing the pyrrole-derived phosphine ligand CyPNH (2-(dicyclohexylphosphino)methyl-1H-pyrrole) was developed, namely, (κP-CyPNH)(κP,κN-CyPN)NiH and the acid-stable trans-(κP-CyPNH)2Ni(OAc)H·HOAc. (κP-CyPNH)(κP,κN-CyPN)NiH stoichiometrically reduces benzaldehyde and acetophenone in a metal-ligand cooperative manner and catalytically dimerizes ethylene and cycloisomerizes 1,5-cyclooctadiene and 1,5-hexadiene. trans-(κP-CyPNH)2Ni(OAc)H·HOAc, available from the protonation of (κP-CyPNH)(κP,κN-CyPN)NiH with acetic acid, catalyzes the cycloisomerization of 1,5-cyclooctadiene more effectively and produces the less thermodynamically favored cycloisomers of 1,5-cyclooctadiene.
- Collett, Joel D.,Guan, Hairong,Krause, Jeanette A.
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p. 345 - 353
(2022/02/16)
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- Selecting double bond positions with a single cation-responsive iridium olefin isomerization catalyst
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The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on noncovalent modifications.
- Camp, Andrew M.,Kita, Matthew R.,Blackburn, P. Thomas,Dodge, Henry M.,Chen, Chun-Hsing,Miller, Alexander J.M.
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supporting information
p. 2792 - 2800
(2021/03/01)
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- METAL ORGANIC FRAMEWORKS, THEIR SYNTHESIS AND USE
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A novel metal organic framework, EMM-33, is described having the structure of UiO-67 and comprising bisphosphonate linking ligands. EMM-33 has acid activity and is useful as a catalyst in olefin isomerization. Also disclosed is a process of making metal organic frameworks, such as EMM-33, by heterogeneous ligand exchange, in which linking ligands having a first bonding functionality in a host metal organic framework are exchanged with linking ligands having a second different bonding functionality in the framework.
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Page/Page column 15
(2018/11/26)
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- Olefin oligomerization via new and efficient Br?nsted acidic ionic liquid catalyst systems
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Olefin oligomerization reaction catalyzed by new catalyst systems (a Br?nsted-acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co-catalyst) has been investigated. The synthesized Br?nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV), 1H nuclear magnetic resonance (NMR), and 13C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co-catalysts, catalyst ratios (mole ratio of ionic liquid to co-catalyst), reaction time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1-(4-sulfonic acid)butyl-3-hexylimidazolium hydrogen sulfate ([HIMBs]HSO4) exhibited the best catalytic activity under the tested reaction conditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respectively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experimental products.
- Wang, Guoqin,Song, Heyuan,Li, Ruiyun,Li, Zhen,Chen, Jing
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p. 1110 - 1120
(2018/05/28)
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- Selective Dimerization of Propylene with Ni-MFU-4l
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We report the selective dimerization of propylene to branched hexenes using Ni-MFU-4l, a solid catalyst prepared by cation exchange. Analysis of the resulting product distribution demonstrates that the selectivity arises from 2,1-insertion and slow product reinsertion, mechanistic features reproduced by a molecular nickel tris-pyrazolylborate catalyst. Characterization of Ni-MFU-4l by X-ray absorption spectroscopy provides evidence for discrete, tris-pyrazolylborate-like coordination of nickel, underscoring the small-molecule analogy that can be made at metal-organic framework nodes.
- Comito, Robert J.,Metzger, Eric D.,Wu, Zhenwei,Zhang, Guanghui,Hendon, Christopher H.,Miller, Jeffrey T.,Dinc?, Mircea
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supporting information
p. 1681 - 1683
(2017/05/15)
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- Low Temperature Oligomerization of Ethylene over Ni/Al-KIT-6 Catalysts
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Abstract: In this paper, we have studied the oligomerization of ethylene with a liquid heptane solvent over bifunctional Ni catalysts in a continuous flow reactor. We have prepared an Al-containing KIT-6 silica that was used as a support after calcination in the temperature range of 300–900 °C. The Ni/Al-KIT-6 catalysts had uniform mesopores with diameters in the range of 5.4–6.3 nm, excepting Ni/Al-KIT-6 (900). The calcination temperature of Al-KIT-6 support changed the surface acidity as well as the interaction of Ni2+ and acid sites for the Ni catalysts, as determined by temperature-programmed desorption of ammonia, temperature-programmed reduction, infrared spectroscopy after the adsorption of pyridine, solid-state 27Al magic-angle spinning nuclear magnetic resonance spectroscopy, and X-ray adsorption spectroscopy. Among the tested catalysts, the Ni/Al-KIT-6 (300) showed the highest ethylene conversion because of the increased intimate contact between Ni2+ and acid sites. The strong interaction of Ni2+ species and the support is not effective in increasing active sites for ethylene conversion. The Ni/Al-KIT-6 catalysts produced internal linear C4 and C6 olefins with high selectivity. The Ni/Al-KIT-6 (300) had 2.2–6.1 times lower selectivities toward 2-ethyl-1-butene than other catalysts at similar ethylene conversions. The reaction product mixture showed that the Ni/Al-KIT-6 catalysts shifted the product distribution towards acid-catalyzed oligomerization/cracking/realkylation products (i.e. C3, C7, C7, and C8+ olefins) as the concentration of Br?nsted acid sites increased. Among the tested catalysts, the Ni/Al-KIT-6 (300) showed the highest yield of C4 and C6 olefins (78.3%). Graphical Abstract: [Figure not available: see fulltext.].
- Hwang, Ahron,Kim, Sungtak,Kwak, Geunjae,Kim, Seok Ki,Park, Hae-Gu,Kang, Seok Chang,Jun, Ki-Won,Kim, Yong Tae
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p. 1303 - 1314
(2017/05/19)
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- Dimerization method for high activity and selectivity propylene
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The invention provides a dimerization method for high activity and selectivity propylene. The method includes the following steps that methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) is used as a catalyst promoter, and the propylene is subjected to a dimerization reaction under the catalytic action of an ethylidene bridged substituted diindene titanium group metal complex catalyst; and the ethylidene bridged substituted diindene titanium group metal complex catalyst is an internal compensation (meso-) ethylidene bridged substituted diindene titanium group metal complex catalyst or a racemization (rac-) ethylidene bridged substituted diindene titanium group metal complex catalyst. Compared with the prior art, the dimerization method provided by the invention is high in catalytic activity and high in dimerization selectivity, the rate can reach 99%, numerous follow-up operation steps in separation of products with the high degree of polymerization are omitted, the industrialization cost is reduced, and the industrial production needs can be met.
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Paragraph 0114; 0115; 0116; 0118-0121; 0124-0139; 0142-0153
(2017/06/02)
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- One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
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For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
- Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
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p. 2961 - 2973
(2017/02/05)
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- PROCESSES FOR CONVERSION OF BIOLOGICALLY DERIVED MEVALONIC ACID
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The invention relates to a process comprising reacting mevalonic acid, or a solution comprising mevalonic acid, to yield a first product or first product mixture, optionally in the presence of a solid catalyst and/or at elevated temperature and/or pressure. The invention further relates to a process comprising: (a) providing a microbial organism that expresses a biosynthetic mevalonic acid pathway; (b) growing the microbial organism in fermentation medium comprising suitable carbon substrates, whereby biobased mevalonic acid is produced; and (c) reacting said biobased mevalonic acid to yield a first product or first product mixture.
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Paragraph 0146
(2016/06/13)
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- CATALYST AND PROCESS FOR THE CO-DIMERIZATION OF ETHYLENE AND PROPYLENE
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Disclosed are novel catalyst solutions comprising an organic complex of nickel, an alkyl aluminum compound, a solvent, and a phosphine compound, that are useful for the preparation of butenes, pentenes and hexenes by the co-dimerization or cross-dimerization of ethylene and propylene. Also disclosed are processes for the dimerization of ethylene and propylene that utilize these catalyst solutions. The catalyst systems described herein demonstrate that, depending on the choice of phosphine compound used with the catalytically active nickel, it is indeed possible to lower the concentration of hexene olefins relative to butenes and pentenes, even in the presence of excess propylene. The selectivity to the linear or branched pentene product can also be controlled by the selection of the phosphine compound. The catalyst solutions may be used with mixtures of olefins.
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Paragraph 0082
(2015/03/28)
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- Highly selective propylene dimerization catalyzed by C1- symmetric zirconocene complexes
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A series of ethylene-bridged C1-symmetric ansa-(3-R-indenyl) (fluorenyl) zirconocene complexes (1, 2, 3, 4, 5, 6, 7, 8, 9) incorporating a pendant arene substituent on the 3-position of indenyl ring have been synthesized. The structure of complex 4 was further confirmed by X-ray diffraction analysis. When activated with methylaluminoxane, four sterically less encumbered complexes 1, 2, 4 and 5 could catalyze the dimerization of propylene in toluene at 100°C to afford 2-methyl-1-pentene with high selectivities up to 95.7-98.4% and moderate activities of 2.00×10 4 to 7.89×104g (mol-Zrh)-1. Copyright
- Huang, Wenzhong,Wang, Yan,Ma, Haiyan,Huang, Jiling
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p. 413 - 422
(2014/06/09)
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- Ethylene-bridged C1-symmetric ansa-(3-R-indenyl)(fluorenyl) zirconocene complexes for propylene dimerization or polymerization: The effect of R group
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A series of ethylene-bridged C1-symmetric ansa-(3-R-indenyl) (fluorenyl) zirconocene complexes 3a-i (R = 2-[2-(4-methylphenyl)propyl], 3a; R = 2-[2-(3,5-dimethylphenyl)propyl], 3b; R = 2-(2-benzylpropyl), 3c; R = 2-methylbenzyl, 3d; R = 2-(2-cyclohexylpropyl), 3e; R = 2-[2-(1-cyclohexenyl) propyl], 3f; R = 2-(2-n-butylpropyl), 3g; R = cyclohexyl, 3h; R = iPr, 3i) were synthesized by a salt metathesis method and characterized by NMR spectroscopy, elemental analysis (or HRMS) and X-ray diffraction (3e and 3h). Upon activation with methylaluminoxane, most of these zirconocene complexes exhibited sufficient catalytic activities up to 2.5 × 105 g C6/(mol-Zr·h) and high selectivities up to 99% toward propylene dimerization, affording 2-methyl-1-pentene as the major isomer which was confirmed by gas chromatography. Remarkably, the selectivity and activity of complexes 3a-i were significantly influenced by the structural features of the substituent on the 3-position of indenyl ring: a pendant aryl or alkyl group linked by a quaternary carbon bridge provided the complex with high selectivities in the range of 89.9-99.0% for 2-methyl-1-pentene and low to moderate catalytic activities; the lack of a quaternary carbon bridge within the substituent would lead to mainly polypropylenes of low molecular weight. The steric hindrance around the active metal center induced by the pendant group might be responsible for the catalytic dimerization behavior, and the presumed mechanism was discussed. In addition, for complexes 3h and 3i, the selectivity for propylene dimerization could also be enhanced with the increase of reaction temperature. Noticeably, most of these ansa-zirconocene complexes exhibit excellent thermal stability at 100 °C, which is important with regard to industrial application. 2014 Elsevier Ltd. All rights reserved.
- Wang, Yan,Huang, Wenzhong,Ma, Haiyan,Huang, Jiling
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- Towards a practical development of light-driven acceptorless alkane dehydrogenation
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The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3) 2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations.
- Chowdhury, Abhishek Dutta,Weding, Nico,Julis, Jennifer,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6477 - 6481
(2014/06/24)
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- Homogeneous Dimerization Catalysts Based on Vanadium
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A series of new bis(imino)pyridine vanadium(III) complexes was synthesized according to formula: They were tested for the homogeneous catalytic dimerization of propylene after activation with MAO and showed excellent selectivity for dimerization. The catalysts can be used with or without PPh3 as an additive to produce ≧80% dimerized alkenes.
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Page/Page column 4; 6
(2011/04/18)
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- Chemical development of an α2δ ligand, (3 S,5 R)-3-(Aminomethyl)-5-methyloctanoic acid
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Three synthetic approaches, suitable for the large scale manufacture of the α2δ-ligand, (3S,5R)-3-(aminomethyl)-5-methyloctanoic acid 3, have been evaluated. The selected seven step manufacturing process has then been optimized and used to deliver over 20 kg of API; salient features of the synthesis include the use of 4,4,4-trimethoxybutyronitrile as an efficient four carbon amino acid equivalent. Highly selective kinetic resolution of the C3 stereocentre was accomplished via diastereoselective hydrolysis of a cyanoester intermediate using Amano Lipase PS-SD. Extensive process optimisation of the route starting from (R)-2-methylpentanol, led to significant improvements through telescoping, with less than 62 kg of solvent being needed to produce 1 kg of API.
- Murtagh, Lorraine,Dunne, Catherine,Gabellone, Gino,Panesar, Niamh J.,Field, Stuart,Reeder, Lisa M.,Saenz, James,Smith, George P.,Kissick, Kyle,Martinez, Carlos,Van Alsten, John G.,Evans, Margaret C.,Franklin, Lloyd C.,Nanninga, Thomas,Wong, John
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p. 1315 - 1327
(2012/01/12)
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- Homogeneous catalytic dimerization of propylene with bis(imino)pyridine vanadium(III) complexes
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A series of new bis(imino)pyridine vanadium(III) complexes was synthesized. They were tested for the homogeneous catalytic dimerization of propylene after activation with MAO. The activity and selectivity depend on the ligand structure of the corresponding organic coordination compound. The influence of PPh3 as an additive was investigated and high dependency could be observed.
- Lang, Julian R.V.,Denner, Christine E.,Alt, Helmut G.
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experimental part
p. 45 - 49
(2010/07/08)
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- Propylene dimerization in the presence of nickel hydride complexes formed in situ
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We study the influence of nickel hydride complexes formed in situ by reaction nickel(0) complexes having phosphorus-containing ligands with Broensted acids in the presence of various modifiers on a catalyst turnover and selectivity in propylene dimerization. The activating action of boron trifluoride etherate is considered. Pleiades Publishing, Ltd., 2010.
- Shmidt,Titova,Belykh,Gomboogiin
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scheme or table
p. 205 - 213
(2011/04/24)
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- High yield of liquid range olefins obtained by converting i-propanol over zeolite H-ZSM-5
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Methanol, ethanol, and i-propanol were converted under methanol-to-gasoline (MTH)-like conditions (400°C, 1-20 bar) over zeolite H-ZSM-5. For methanol and ethanol, the catalyst lifetimes and conversion capacities are comparable, but when i-propanol is use
- Mentzel, Uffe V.,Shunmugavel, Saravanamurugan,Hruby, Sarah L.,Christensen, Claus H.,Holm, Martin S.
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experimental part
p. 17009 - 17013
(2010/03/23)
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- Hafnocene catalysts for selective propylene oligomerization: Efficient synthesis of 4-methyl-1-pentene by β-methyl transfer
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A series of hafnocene complexes (η5-C5Me 4R1)(η5-C5Me4R 2)HfCl2 with [R1, R2] = [H, H] (1), [Me, H] (2), [Me, Me] (3), [Et, Me] (4), [iPr, Me] (5), [SiMe 3, Me] (6), [tBu, Me] (7), [nBu, Me] (8), [tBu, Me] (9), [Et, Et] (10), [nBu, nBu] (11), [iBu, iBu] (12) was tested as catalyst precursors for propylene oligomerization. Upon activation with methylaluminoxane or [Ph 3C][B(C6F5)4]AliBu 3, complexes 2-4 and 8-12 catalyzed the dimerization of propylene to produce 4-methyl-1-pentene with selectivities ranging from 23.9 to 61.6 wt % in the product mixture. The selectivity was dependent on the nature of the substituents R1 and R2, with the highest value found for (η5-C5Me4iBu) 2HfCl2 (12). Rapid deactivation was observed for 5-7, whereas (η5-C5Me4H)2HfCl 2 (1) polymerized propylene. 4-Methyl-1-pentene is proposed to form by repeated 1,2-insertion of propylene into the hafnocene methyl cation, followed by selective β-methyl elimination. Detailed analysis of the byproduct distribution (isobutene, 1-pentene, 2-methyl-1-pentene, 2,4-dimethyl-1-pentene, 4-methyl-1-heptene, 4,6-dimethyl-1-heptene), determined by gas chromatography, was performed with the aid of a stochastic simulation involving rate constants for the propagation by insertion, β-hydride elimination, and β-methyl elimination. The rate of termination is dependent on the structure of the growing chain of the active species as well as on the bulkiness of the cyclopentadienyl ligands. The selectivity highly depends on the reaction conditions (pressure, temperature, concentration of methylaluminoxane). The rates of β-methyl elimination leading to 4-methyl-1-pentene were proportional to propylene pressure for 2-4 and 8-10 but practically independent from propylene pressure for the sterically bulkier derivatives 11-12.
- Suzuki, Yasuhiko,Yasumoto, Takahiro,Mashima, Kazushi,Okuda, Jun
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p. 13017 - 13025
(2008/02/08)
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- Fast propene dimerization using upper rim-diphosphinated calix[4]arenes as chelators
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The complexes [NiBr2·1] and [NiBr2· 2], containing the upper rim-diphosphinated calixarenes 5,17-bis(diphenylphosphino)-25,26,27,28-tetrapropoxycalix[4]arene (1) and 5,17-dibromo-11,23-bis(diphe-nylphosphino)-25,26,27,28-tetrapropoxycalix[4] arene (2) were assessed as propene dimerization catalysts. Combined with methylaluminoxane, both complexes result in highly efficient dimerization catalysts displaying C6 selectivities in the range 80-97% and activities that compare with the best reported systems, the latter using PCy3 as ligand. The origin of the remarkable activities of the calixarene derivatives may be the ability of the diphosphine to undergo a periodic bite angle increase that incidentally favors the insertion step. Calixarenes such as 1 or 2, which each incorporate two "stable" Ph2PAr moieties, constitute interesting alternatives to the use PCy3 in propene dimerization.
- Lejeune, Manuel,Semeril, David,Jeunesse, Catherine,Matt, Dominique,Lutz, Pierre,Toupet, Loic
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p. 881 - 886
(2007/10/03)
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- Novel neutral arylnickel(II) phosphine catalysts containing 2-oxazolinylphenolato N-O chelate ligands for ethylene oligomerization and propylene dimerization
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A series of new neutral arylnickel(II) phosphine complexes 1 bearing 2-oxazolinylphenolato ligands [2-(4-R1-5-R2-C3H2NO) -C6H4O]Ni (2-R4-4-R3-C6H3 (PPh3) were synthesized by reactions of sodium salts of 2-(4,5-dihydro-2-oxazolyl)phenol derivatives with trans-Ni(Ar)(Cl (PPh3)2 or by direct reactions of the ligands with trans-Ni(Ar)(Cl)(PPh3)2 in the presence of NEt3. These neutral Ni(II) complexes 1 exhibited high activities and selectivities in ethylene oligomerization and propylene dimerization. The catalytic activities and the product distributions were dependent on the selection of various organoaluminum cocatalysts and phosphine scavenger (Ni(COD)2). The effects of various reaction conditions on ethylene oligomerization were also examined. The highest activity of 5.51×105 g oligomers/(mol Ni · h) and 83% selectivity of C6 internal olefins were obtained in 1a/MAO catalytic system in ethylene oligomerization. The oligomers consisted mainly of lower carbon olefins in the range of C4-C8. Complexes 1 showed the moderate tolerance of polar additives in ethylene oligomerization. The highest activity of 1a/MAO in propylene dimerization reached to 1.32×105 g oligomers/(mol Ni · h).
- Zhao, Wei,Qian, Yanlong,Huang, Jiling,Duan, Jianjun
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p. 2614 - 2623
(2007/10/03)
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- Nickel(II) compounds derived from tripod ligands: Efficient catalysts for the stereoselective heterodimerization of styrene and propene
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The tripod ligands RCH2C(CH2X)(CH2Y)(CH2Z) form tetracoordinate compounds with NiHal2. If two of the donor functions X, Y, Z are phosphanes, square-planar coordination is observed. In contrast, donor sets X,Y,Z = P,N,N or N,N,N form tetrahedral compounds, by P,N or N,N coordination, that are active in the catalysis of olefin oligomerization with MAO as a co-catalyst. These catalyst systems are also active in the stereoselective heterodimerization of olefins. The co-dimerization of styrene and propene by these systems leads to 4-phenyl-2-pentene almost exclusively, with regioselectivities up to 98% and (E)/(Z) ratios of up to 95:5, surpassing other reported catalysts for this process. The products of these catalytic transformations have been fully characterized by GC/MS techniques as well by isolation, NMR and MS characterization of the pure compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Faissner, Ralf,Huttner, Gottfried
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p. 2239 - 2244
(2007/10/03)
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- MCM-41 immobilised borate co-catalyst for metallocene catalyzed propene oligomerisation
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Reaction of tris(pentafluorophenyl)boron with the silanol groups of MCM-41 resulted in the heterogeneous tris(pentafluorophenyl)borate anion. This immobilised weakly-coordinating anion retains metallocenes, thus yielding a heterogeneous propene oligomerisation catalyst. Activity comparable to the corresponding homogeneous catalyst can be obtained. The products typically consist of over 90% 1-alkenes with Flory-Schulz carbon number distribution.
- Kwanten, Marc,Carriere, Brenda A. M.,Grobet, Piet J.,Jacobs, Pierre A.
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p. 1508 - 1509
(2007/10/03)
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- Method for producing of 2,3-dimethylbutene-1 and 2,3-dimethylbutene-2
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There is disclosed a method for producing 2,3-dimethylbutene-1 and 2,3-dimethylbutene-2, which is characterized by the steps of (a) dimerizing propylene in a propylene-dimerization step using a nickel complex catalyst as described below as a propylene-dimerization catalyst having propylene-dimerization activity and DMB-1 selectivity, (b) rectifying the resulting reaction solution to obtain 2,3-dimethylbutene-1 as a distillate and a distillation residue containing 2,3-dimethylbutene-1 in a 2,3-dimethylbutene-1 distillation step, (c) allowing the distillation residue to contact with sulfuric acid, sulfonic acid or hetetopolyacid to isomerize 2,3-dimethylbutene-1 in said distillation residue into 2,3-dimethylbutene-2 in an isomerization step, and (d) rectifying the resulting isomerization reaction solution to obtain 2,3-dimethylbutene-2 in a 2,3-dimethylbutene-2 distillation step, wherein said nickel complex catalyst containing (A) at least one nickel compound and the like, (B) a trialkylaluminum, (C) a trivalent phosphorus compound, (D) a fluorinated isopropanol or a halogenated phenol (E) at least one sulfur compound selected from a sulfonic acid and a dialkylsulfuric acid.
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Page column 5-6
(2008/06/13)
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- Debrominations of vic-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications
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Debrominations of vic-dibromides with diaryl tellurides 1-4 and di-n-hexyl telluride (9) are described. A mechanistic explanation of the debromination is offered which accounts for several key experimental observations: (1) the reaction is highly stereoselective with erythro-dibromides giving trans-olefins and threo-dibromides giving cis-olefins, (2) the reaction is accelerated by more electron-rich diorganotellurides, (3) the reaction is accelerated in a more polar solvent, (4) the reaction is accelerated by the addition of carbocation-stabilizing substituents to the carbons bearing the bromo substituents, and (5) erythro-dibromides are much more reactive than threo-dibromides. It is proposed that bromonium ion formation from the vic-dibromide is slow and rate-determining. Bromonium ion formation is followed by rapid scavenging of "Br-" by the diorganotelluride. The bromonium ion formation provides stereoselectivity and eclipsing interactions lower the reactivity of threo-dibromides. No intermediate species were observed by 1H NMR.
- Butcher, Timothy S.,Zhou, Feng,Detty, Michael R.
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p. 169 - 176
(2007/10/03)
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- Method for dimerizing an α-olefin
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A new class of olefin dimerization catalysts and an efficient method for their preparation is disclosed. B (C6 F5)3 reacts quantitatively with Group 4 metallocene type catalysts to yield highly reactive cationic complexes as follows: (L2 MR2)+ X- where L=R2 (C5 H3); R=CR'3 ; R2 =alkyl group (C=1≤20); M=Ti, Zr, Hf; X- =RB(C6 F5)3-, or methylalumoxane. These complexes are potent catalysts and may be used in the dimerization of α-olefins.
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- Synthesis of 2,3-Dimethylbutenes by Dimerization of Propene Using Highly Active Nickel-Phosphine Catalysts in the Presence of Sulfonic Acids and/or Dialkyl Sulfates
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A nickel-phosphine catalyst system consisting of nickel naphthenate, P(cyclo-C6H11)3, AlEt3, and 2,4,6-trichlorophenol (TCP) in the presence of sulfonic acids (CF3SO3H and MeSO3H) or dialkyl sulfates (Me2SO4 and Et2SO2) exhibits remarkable catalytic activity for the dimerization of propene. The catalytic activity (turnover number (TON) for the formation of C6, olefins or 2,3-dimethylbutenes) was enhanced when the catalyst was combined with effective additives, such as Et2SO4 and MeSO3H. The reaction products consisted of 2,3-dimethyl-1-butene (DMB-1) and/or 2,3-dimethyl-2-butene (DMB-2) in high yields (selectivity of dimers based on the reacted propene = 70-80%: selectivity of 2,3-dimethylbutenes in C6 olefins = 78-80%). The ratio of DMB-1/DMB-2 could be controlled by varying the molar ratios of the catalyst ingredients without decreasing in the turnover numbers. Although CF2SO3H was found to be the best additive as far as the catalytic activity and the selectivity of dimers (94-99%) are concerned, the selectivity of 2,3-dimethylbutenes in C6 olefins decreased. The addition of a small amount of water was also effective to enhance the catalytic activity: The turnover number for the formation of 2,3-dimethylbutenes was raised from 7050 to 30360.
- Nomura, Kotohiro,Ishino, Masaru,Suzukamo, Gohfu
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p. 2671 - 2676
(2007/10/03)
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- Nickel(II) Naphthenate Complexes with Phosphorous Amides in Dimerization of Propylene
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Dimerization of propylene in the presence of diethylaluminum chloride and nickel(II) naphthenate complexes with phosphorous amides of the general formulas (RO)2P-NR'2 and (R'2N)3P (where R = C6H5, AlkC6H4; R' = C2H5, C4H9) was studied.The catalytic activity of the systems was examined in relation to the donor properties of these ligands.The procedure for recovery of 2-methyl-2-pentene and 2,3-dimethyl-2-butene from the dimerization products was developed.
- Munshieva, M. K.
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p. 1779 - 1782
(2007/10/03)
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- Formation of HNCO during Catalytic Reduction of NOx with Olefins over Cu/ZSM-5
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Gaseous cyanic acid (HNCO) is formed in the temperature range 513-666 K during the selective catalytic reduction of NOx with olefins (ethene, propene) over Cu/ZSM-5 under dry conditions, whereas with ammonia no HNCO is observed in the presence of water in
- Radtke, Frank,Koeppel, Rene A.,Baiker, Alfons
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p. 427 - 428
(2007/10/02)
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- The Reactions of Hexyl Ions on USHY
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We have examined the behavior of C6 carbenium ions in the cracking of 2-methylpentane on USHY.We find that at 400 deg C, hexyl carbenium ions undergo hydride addition from the feed 10 times faster than proton release to the Broensted base.This makes the isomerization of the feed a much faster reaction than the production of olefins with the same carbon number.We also find that proton release from a C6 ion to the Broensted base requires a higher activation energy than a hydride transfer from the feed to the same ion.At high temperatures isomerization is therefore reduced with respect to olefin production.The presence of steam in the cracking mixture weakens the Broensted base, and reduces the rates of all reactions but encourages hydride transfer over proton release.This enhances the formation of paraffinic isomers of the feed.At the low steam dilution ratio of 0.07 mol/mol, hydride transfer in 2-methylpentane is as much as 18 times faster than proton release, resulting in a highly isomerized, highly saturated product.The full picture of individual ion fates is presented and gives an important insight into the causes underlying cracking selectivity and the possible methods for its control.
- Wojciechowski, B. W.,Zhao, Y.-X.
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p. 239 - 253
(2007/10/02)
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- Ethene Transformation on HZSM-5 studied by Combined UV-VIS Spectroscopy and On-line Gas Chromatography
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Combined UV-VIS spectroscopy in transmission mode and on-line gas chromatography have been performed on a HZSM-5 zeolite in a microreactor operating under a continous gas flow of either 2 or 20 cm3 min-1 with a mixture of 5 vol.percent ethene in nitrogen.The UV-VIS experiments were carried out in situ up to 573 K and ex situ up to 673 K.Carbocations formed at temperatures up to 473 K are of the cyclopentenyl and/or cyclohexenyl type.Their absorption maxima are between 278 and 313 nm.Moreover, a strong adsorption-sorption is initially established at room temperature which then decreases with time.No appreciable spectroscopic difference could be ascertained between in situ and ex situ measurements up to 473 K.At 548 K and above the most intense absorption maximum is slightly blue shifted.The first volatile reaction products could be identified at lower space velocity at >/= 373 K and aromatics were detected from 573 K.The conversion is strongly dependent on the space velocity.At 523 K and above new absorption bands develop at ca. 375 and 440 nm.The former disappears above 573 K and the latter shifts towards 417 nm with increasing temperature.From the location of these bands and from reference experiments we can conclude that for toluene the alkyl-transfer mechanism seems to be valid between 523 and 573 K, and the benzylic-cation mechanism between 573 and 673 K.
- Melsheimer, Joerg,Ziegler, Dietrich
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p. 2101 - 2108
(2007/10/02)
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- Unusual Directive Effects in the Hydroboration of β,β-Disubstituted Enamines. Conversion of α-Substituted Aldehydes to the Corresponding Alkenes and β-Amino Alcohols
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A comprehensive study of the conversion of β,β-disubstituted enamines into the corresponding alkenes and β-amino alcohols by hydroboration-elimination and hydroboration-oxidation, respectively, has been carried out.The amine moiety of β,β-disubstituted enamines was found to exert a decisive influence on the regioselectivity of the hydroboration reaction involving borane methyl sulfide (BMS).Thus, in the hydroboration of morpholino and piperidino enamines, the boron atom is initially placed predominantly in the α-position.Conversely, the pyrrolidino enamines direct the boron atom exclusively to the β-position.Three oxidizing agents, trimethylamine N-oxide, sodium perborate, and 30 percent hydrogen peroxide-solid sodium hydroxide, were tried in order to optimize the oxidation of the intermediate organoborane derivatives to the corresponding amino alcohols.Our results clearly indicated that 30 percent hydrogen peroxide-solid sodium hydroxide is best suited for this transformation.The yield of amino alcohol ranged from good to essentially quantitative.Enamines derived from β-aryl aldehydes, upon hydroboration with BMS followed by methanolysis and oxidation with neutral hydrogen peroxide, gave the corresponding 1,1-disubstituted alkenes.Contrary to the regioselectivity observed in the hydroboration reactions involving BMS, the hydroboration of β,β-disubstituted enamines using 9-borabicyclononane (9-BBN) gave the trialkylborane intermediates in which the boron atom was placed exclusively at the β-position regardless of the amine moiety of the enamine.These trialkylborane derivatives were very stable and did not undergo the usual elimination reaction with either methanol or sodium hydroxide.However, on thermal decomposition, these afforded the corresponding 1,1-disubstituted alkenes in high yields.
- Singaram, Bakthan,Goralski, Christian T.,Fisher, Gary B.
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p. 5691 - 5696
(2007/10/02)
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- On the Mechanism of Oligomerization of Propylene by (C5Me5)2MCl2/Methylalumoxane Catalysts (M=Zr, Hf)
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In the oligomerization of propylene by (C5Me5)2MCl2 (M=Zr, Hf)/methylalumoxane, formation of abnormal oligomers such as 1-pentene(C5), 2,4-dimethyl-1-pentene(C7), 4-methyl-1-heptene(C8), and 2,4,6-trimethyl-1-heptene(C10) besides normal oligomers such as 4-methyl-1-pentene(C6) and 4,6-dimethyl-1-heptene(C9) is indicative of the mixing of unusual β-CH3 and usual β-H transfer terminations from each growing carbon chain which was initiated by insertion of propylene into either M-H or M-Me bond.
- Mise, Takaya,Kageyama, Akiko,Miya, Shinya,Yamazaki, Hiroshi
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p. 1525 - 1528
(2007/10/02)
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- Acid-Base Properties of Modified Aluminas
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The acid-base properties of modified aluminas (SO42-, PO43-, Cl-, F-, Mg2+ and Na+, 0.2-2.0 wt.percent) have been investigated by FTIR spectroscopy of probe molecules (pyridine and CDCl3), CO2 TPD and the dehydration of 4-methyl-pentan-2-ol.The results of these methods and those of previous NH3 TPD studies were compared in order to establish a classification of our aluminas.There is very good agreement between the results of the five methods.The various modifying ions have effects as summarised in the following acidity-basicity scale: Na+ 2+ 3- - 2- , - increasing basicity).Fluorine is distinguished from the other ions as it is able to create Broested-acidic sites.CO2 TPD is an adequate method for basicity measurement.NH3 and CO2 TPD give complementary results.Furthermore, FTIR spectroscopy of adsorbed CDCl3 gives valuable information on the effects of ions on the basic strengths.
- Berteau, Pascal,Kellens, Marie-Ange,Delmon, Bernard
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p. 1425 - 1431
(2007/10/02)
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- Komplexkatalyse XXIX. Kationische Allylbis(ligand)nickel(II)hexafluorophosphate PF6 und die Kombination /Et2AlCl als Katalysatoren fuer die Propendimerisation
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The cationic allylbis(ligand)nickel(II) complexes PF6 with L=P(OPh)3, P(OThym)3 and SbPh3 were found to be efficient catalysts for the oligomerization of propene under a l0 bar pressure of the monomer.The main products are dimers, and specifically the methylpentenes.The /Et2AlCl system catalyzes propene dimerization at atmospheric pressure with high activity, and selectivity similar to that of the cationic allylbis(ligand)nickel(II) complexes.In a kinetic analysis the rate law and the activation parameters ΔH and ΔS were determined for the propene dimerization with this catalytic system.
- Balbolov, Entscho,Mitkova, Magdalena,Kurtev, Kurty,Gehrke, Joerg-Peter,Taube, Rudolf
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p. 247 - 256
(2007/10/02)
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- Copper(II) Triflate, a New Reagent for Mild Dehydration of Alcohols: Synthetic Usefulness and Mechanistic Insight
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The effectiveness of copper(II) triflate (copper(II) trifluoromethanesulfonate) as a new dehydrating reagent for a variety of alcohols has been demonstrated.Based on several control experiments, a possible mechanism is suggested.
- Laali, Khosrow,Gerzina, Robert J.,Flajnik, Christine M.,Geric, Cynthia M.,Dombroski, Ann Marie
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p. 607 - 611
(2007/10/02)
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- Nuclear Synthons: Mesyltriflone as an Olefin Polyanion Equivalent
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Mesyltriflone (CF3SO2CH2SO2CH3) is developed as a nuclear synthon reagent capable first of multiple constructions such as alkylations then of Ramberg-Baecklund elimination to a substituted olefin.The alkylations are clean and regiospecific, often amenable to one-pot operation, and in most cases the elimination is smooth.A variety of examples is presented to establish the scope of the method, and the mechanism and stereochemistry are discussed.
- Hendrickson, James B.,Boudreaux, Gerald J.,Palumbo, Paul S.
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p. 2358 - 2366
(2007/10/02)
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- METATHESIS AND OLIGOMERIZATION OF PROPENE OVER MOLYBDENA-ALUMINA CATALYSTS
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Metathesis of propene at 313 K and its oligomerization at 470-550 K were studied over a molybdena-alumina catalyst pretreated under various conditions.Activity of the catalyst decreased in both reactions as a result of elution with nitrogen at high temperature (823 K) after reduction with hydrogen.Ammonia was found to be an effective poison in both reactions.Hydrogen adsorbed at high temperature on reduced catalyst poisoned metathesis but did not influence oligomerization.Conversion in oligomerization of propene and selectivity in formation of C6 alkenes varied in an identical way under various conditions.
- Engelhardt, Jozsef,Kallo, Denes
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p. 249 - 264
(2007/10/02)
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- SELECTIVE HYDROGENATION OF CONJUGATED DIENES CATALYZED BY THIOCYANATOTRIS(TRIPHENYLPHOSPHINE)COBALT(I).
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Thiocyanatotris(triphenylphosphine)cobalt(I) prepared in situ from bis(thiocyanato)bis(triphenylphosphine)cobalt(II), triphenylphosphine, zinc bromide, selectively hydrogenated conjugated dienes to the corresponding cis-monomenes. The C//2-or/ and C//3-methyl substituted 1,3-butadienes enhance the reactivity by a factor of 2. 3 per one methyl group, while C//1- or/and C//4-methyl substituted 1,3-butadienes lower the reactivity by a factor of 1/23 per one methyl group. In the hydrogenation of cyclic conjugated dienes alpha -angle is closely related to the hydrogenation rate. The rates of hydrogenation in cyclic ethers are greater than those in acyclic ethers, but the cis-selectivity in acyclic ethers is much higher.
- Nakayama,Kanai
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- Influence cinetique et chimique d'alcenes sur la pyrolyse d'alcanes: mise au point et nouveaux resultats
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On the basis of previously reported, as well as new, experimental results, a review is presented of the kinetic and chemical influences of alkenes on the pyrolysis of alkanes.The results confirm that the addition of free H. atoms to the double bonds of alkenes is not sufficient to explain their inhibiting influence on the pyrolysis of alkanes.On the contrary, our results show that the processes of addition can account for the chemical effects of added alkenes on the pyrolysis of alkanes, namely, the modifications brought to the nature and the ratio of the products formed during the reaction.The results presented here confirm that the addition of alkyl free radicals to the double bond of alkenes does not lead to important chemical effects.The previously reported experimental results (pyrolysis of ethane in the presence of ethylene or propene, the pyrolysis of 2,2-dimethylbutane in the presence of propene, isobutene, or two isopentenes), completed by our new results (pyrolysis of ethane in the presence of isobutene, pyrolysis of isobutane in the presence of ethylene, of propene, of trans-2-butene, or of 2-methyl-2-butene), can lead to very simple general rules, on the basis of which it is possible to explain the results and to predict the modifications (relating to the nature of the products and to their ratios) that will result from the addition of an alkene during the pyrolysis of an alkane at a temperature of 500 deg C (773 K).Aside from their fundamental aspects, these observations and their mechanistic consequences could be useful for the preparation of models for these thermal reactions, especially for the simplification of complex models.These observations also explain certain facts observed in industry and can help in solving some of the problems associated with the thermal cracking of heavy oils.
- Billaud, Francis,Baronnet, Francois,Niclause, Michel
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p. 2869 - 2884
(2007/10/02)
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- Selective Reductions. 31. Lithium Triethylborohydride as an Exceptionally Powerful Nucleophile. A New and Remarkably Rapid Methodology for the Hydrogenolysis of Alkyl Halides under Mild Conditions
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Lithium triethylborohydride exhibits enormous nucleophilic power in SN2 displacement reactions with alkyl halides, far more powerful than the other common nucleophiles, such as n-butyl mercaptide (14 times), thiophenoxide (20 times), borohydride (1E4 times), and nitrate (1E7 times).The reaction follows second-order kinetics and exhibits typical characteristics of a nucleophilic substitution of the SN2 type.In addition to being the best nucleophile, it is the most powerful nucleophilic reducing agent available for the reduction of alkyl halides, far more powerful and cleaner than lithium aluminum hydride and lithium borohydride.Even hindered alkyl halides, such as cyclohexyl bromide, neopentyl bromide, and exo-norbornyl bromide, undergo facile reduction to the corresponding alkanes in > 96 percent yield with this reagent.Consequently, the new reagent provides a highly useful and simple means as a probe for studying SN2 displacement reactions and also for the facile dehalogenation of hindered alkyl halides where this is required in synthetic transformations.The corresponding deuterated derivative, lithium triethylborodeuteride, conveniently synthesized from lithium deuteride and triethylborane, is useful for the stereospecific introduction of deuterium in the molecule.
- Krishnamurthy, S.,Brown, Herbert C.
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p. 3085 - 3091
(2007/10/02)
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- DIMERIZATION OF PROPYLENE IN THE PRESENCE OF NICKEL-CONTAINING COMPLEX CATALYSTS FIXED ON PHOSPHORYLATED POLYSTYRENE
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The effect of a series of factors (the type of nickel compound, the nature of the phosphorus-containing group, the nature of the solvent, the temperature, etc.) on the dimerization of propylene and on the activity of the nickel-containing complex catalysts fixed to phosphorylated polystyrene was investigated.The activity of the catalysts amounts to 1300-1700 g of the dimers per 1 g of nickel per hour.The main product in the dimeric fraction is 4-methyl-2-pentene.If the reaction is carried out in an alkane medium, the catalysts retain high activity for more than 1000 h.
- Aliev, V. S.,Khanmetov, A. A.,Mamedov, R. Kh.,Kerimov, R. K.,Akhmedov, V. M.
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p. 232 - 235
(2007/10/02)
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- ETUDE DE L'ISOMERISATION DU METHYL-4 PENTENE-1 PAR L'HYDRIDO DIAZOTE TRIS(TRIPHENYLPHOSPHINE)COBALT(I): CoHN2(PPh3)3
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At 25 deg C, and under 1 to 7 bar nitrogen pressure, the isomerization of 4-methyl-1-pentene catalyzed in benzene by CoHN2(PPh3)3 involves two active species: HCoN2(S1)(PPh3)2 and HCo(S1)(PPh3)3, respectively, in greater quantities at higher (P(N2) > 7 bars) and small quantities at P(N2) - O nitrogen pressures. The kinetic study shows that the rate of the reaction is always ruled by the equation:
- Petit, F.,Arzouyan, C.,Peiffer, G.,Gaydou, E.
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p. 261 - 272
(2007/10/02)
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- The Kinetics and Mechanism of Ring Opening of Radicals containing the Cyclobutylcarbinyl System
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The kinetic parameters of β-fission of radicals containing the cyclobutylcarbinyl system have been determined by analysis of the mixtures obtained when suitable chloro-compounds are treated with tributylstannane.Under these conditions ring opening is irreversible and in the rigid bicyclic system (4) is under stereoelectronic control.For ring opening of cyclobutylcarbinyl radical (8) kf = 4.3 x 103 s-1 at 60 deg C, and the best values of the activation parameters appear to be ΔH(excit.) = 12.2 kcal mol-1 and ΔS(excit.) = -7.4 cal mol-1 K-1.Monocyclic systems undergo preferential fission of the more substituted βγ-bond.Methyl substituents at the α-, β-, or δ-positions have little effect but γ-substitution strongly enhances the rate of ring opening.The transition state is reactant-like and has a similar disposition of centres to that (1) for homolytic addition.
- Beckwith, Athelstan L. J.,Moad, Graeme
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p. 1083 - 1092
(2007/10/02)
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