- Fluorination of secondary and primary alcohols by thermal decomposition of electrochemically generated alkoxy triphenylphosphonium tetrafluoroborates
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Replacement of hydroxyl groups in secondary and primary alcohols (1) with a fluorine atom arising from tetrafluoroborate anion has been performed by the electrochemical formation of alkoxy triphenylphosphonium tetrafluoroborates (2) from 1, followed by their thermal decomposition. The procedure is quite simple, involving: (1) constant-current electrolysis of a mixture of 1, Ph3P, and Ph3PH·BF4 in CH2Cl2 in an undivided cell; (2) refluxing a tetrahydrofuran or dioxane solution of the residue afforded by evaporation of the solvent in vacuo after the electrolysis. Cyclic secondary alcohols such as 3β-hydroxy steroids and 2-adamantanol are transformed into the corresponding fluorides in satisfactory yields when the geometry of the leaving group in 2 is suitable for the substitution or an elimination process for 2 to give an alkene is stereochemically forbidden. The fluorination of steroidal alcohols and 4-phenyl-1-cyclohexanol proceeded with complete inversion, demonstrating that a fluorine atom from the tetrafluoroborate anion attacks from the side opposite to the phosphonium moiety in 2 via an SN2 mechanism rather than an SN1 mechanism. The fluorination of acyclic secondary and primary alcohols was performed by the present method in reasonable yields, although the reaction for the latter required more forcing conditions, such as refluxing in dioxane.
- Maeda, Hatsuo,Koide, Takashi,Matsumoto, Sayaka,Ohmori, Hidenobu
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- Approximate rate constants for the addition of alkyl radicals to allylstannanes
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Rate constants for the addition of alkyl radicals to allylstannanes lie in the range of 104-105 M-1 s-1 at 50-80°C.
- Curran,Van Elburg
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- Synergistic sex pheromone components of white-spotted tussock moth, Orgyia thyellina
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In 1996, the exotic white-spotted tussock moth (WSTM), Orgyia thyellina (Lepidoptera: Lymantriidae), was discovered in Auckland, New Zealand. Because establishment of WSTM would threaten New Zealand's orchard industry and international trade, eradication of WSTM with microbial insecticide was initiated. To monitor and complement eradication of WSTM by capture of male moths in pheromone-baited traps, pheromone components of female WSTM needed to be identified. Coupled gas chromatographic-electroantennographic detection analysis of pheromone gland extract revealed several compounds that elicited responses from male moth antennae. Mass spectra of the two most EAD-active compounds suggested, and comparative GC-MS of authentic standards confirmed, that they were (Z)-6-heneicosen-11-one (Z6-11-one) and (Z)-6-heneicosen-9- one, the latter termed here 'thyellinone.' In field experiments in Japan, Z6- 11-one plus thyellinone at a 100:5 ratio attracted WSTM males, whereas either ketone alone failed to attract a single male moth. Addition of further candidate pheromone components did not enhance attractiveness of the binary blend. Through the 1997-1998 summer, 45,000 commercial trap lures baited with 2000 μg of Z6-11-one and 100 μg of thyellinone were deployed in Auckland towards eradication of the residual WSTM population.
- Gries, Gerhard,Clearwater, John,Gries, Regine,Khaskin, Grigori,King, Skip,Schaefer, Paul
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- SELECTIVE MIXED COUPLING OF CARBOXYLIC ACIDS-III. SYNTHESIS OF CYCLOPENTADECANONE FROM CYCLIC TETRAACYL DIPEROXIDES
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Cyclopentadecanone (1b) and cyclotetradecane (1a) were prepared in 53 and 83percent yield by thermolysis or photolysis of the cyclic tetraacyl diperoxides 4b and 4a.The compounds 4a, b were obtained from diperoxydodecanedioic acid (3) and the acyl chloride 5a or the dicarboxylic acid 2b.
- Feldhues, Michael,Schafer, Hans. J.
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- Iron-catalyzed cross-coupling of alkenyl sulfides with grignard reagents
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(Chemical Equation Presented) The iron-catalyzed cross-coupling reaction of alkenyl sulfides with Grignard reagents is described. While the cross-coupling proceeds efficiently at alkenyl-S bonds, almost no cross-coupling takes place at aryl-S bonds, attesting to a unique selectivity of iron catalysis. The beneficial effect of potentially coordinating 2-pyrimidyl group on sulfur is also described.
- Itami, Kenichiro,Higashi, Shohei,Mineno, Masahiro,Yoshida, Jun-Ichi
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- Reduction of fatty acid methyl esters to fatty alcohols to improve volatility for isotopic analysis without extraneous carbon.
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Carbon in derivatization groups cannot be distinguished from analyte carbon by chromatography-based high-precision compound-specific or position-specific isotope analysis. We report the reduction of fatty acid methyl esters to fatty alcohols to facilitate high-quality chromatographic separation, without addition of extraneous carbon, with subsequent high-precision position-specific isotope analysis. Methyl palmitate is quantitatively reduced to 1-hexadecanol by LiAlH4 in a one-step reaction. Gas-phase pyrolysis of 1-hexadecanol results in a series of monounsaturated alcohols and alpha-olefins analogous to fragmentation found for methyl palmitate, as well as an additional peak corresponding to the pyrolytic dehydration product, 1-hexadecene. Carbon isotope analysis of the fragments yielded precision of SD (delta 13C) 0.4/1000. Results of position-specific analysis of very low enrichment [1-13C]-1-hexadecanol (delta 13C = -4.00/1000) showed no evidence of scrambling of the C1 position, and isotope ratios in accord with expectations. The pyrolysis product 1-hexadecene was isotopically enriched relative to 1-hexadecanol, which may cause minor depletion of other pyrolysis products that can be taken into account by routine calibration. The procedure is general and can be extended to compound-specific and position-specific analysis of moderate molecular weight, low-volatility analytes containing acid groups that would otherwise be blocked with methyl, ethyl, acetyl, or trimethyl silyl groups containing extraneous carbon.
- Corso,Lewis,Brenna
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- A catalytic application of Co/Zr heterobimetallic complexes: Kumada coupling of unactivated alkyl halides with alkyl grignard reagents
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Tris(phosphanylamide) early/late heterobimetallic Zr/Co complexes, ClZr(R′NPR2)3CoI [R′ = iPr, R = Ph (1), R′ = 2,4,6-trimethylphenyl, R = iPr (2), R′ = R = iPr (3)], have been utilized as catalysts for the cross-coupling of alkyl halides with n-octylmagnesium bromide. While yields are consistently higher for alkyl bromide substrates, it is found that these unusual heterobimetallic complexes are also active towards more challenging alkyl chloride substrates. This is particularly interesting in light of the fact that monometallic cobalt complexes are inert towards these substrates, suggesting that Zr also plays a role in catalysis. Radical trapping studies suggest that a one-electron transfer radical oxidative addition pathway is operative.
- Zhou, Wen,Napoline, Jonathan Wesley,Thomas, Christine M.
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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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- Efficient iridium-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to internal or terminal alkenes
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Vaska's complex, IrCl(CO)(PPh3)2, when combined with KI as an additive, served as an excellent catalyst for the decarbonylation of long-chain aliphatic carboxylic acids to give internal alkenes with high selectivity. On combination with KI and Ac2O as additives under controlled temperatures, decarbonylation proceeded to give terminal alkenes with high selectivity.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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- Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydroboration and Dehydroboration
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We report a dehydroboration process that can be coupled with chain-walking hydroboration to create a one-pot, contra-thermodynamic, short-or long-range isomerization of internal olefins to terminal olefins. This dehydroboration occurs by a sequence comprising activation with a nucleophile, iodination, and base-promoted elimination. The isomerization proceeds at room temperature without the need for a fluoride base, and the substrate scope of this isomerization is expanded over those of previous isomerizations we have reported with silanes.
- Bloomer, Brandon,Butcher, Trevor W.,Ciccia, Nicodemo R.,Conk, Richard J.,Hanna, Steven,Hartwig, John F.
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supporting information
p. 1005 - 1010
(2022/02/10)
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- Palladium-Catalyzed Oxidative Dehydrosilylation for Contra-Thermodynamic Olefin Isomerization
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We report a newly developed, palladium-catalyzed dehydrosilylation of terminal alkylsilanes that combines with chain-walking hydrosilylation to create a one-pot isomerization of internal olefins to terminal olefins. This catalytic dehydrosilylation is one of the few examples of thermal catalytic functionalizations of unactivated alkylsilanes. The reaction involves transmetalation of an alkylsilane, β-hydride elimination, release of the terminal olefin, and reoxidation of the palladium catalyst. A variety of linear internal olefins underwent the overall isomerization to terminal olefins in good yields and in good regioselectivities. Particularly noteworthy, isomerizations occurring over seven carbon units proceeded in yields that are comparable to those of isomerizations occurring over one carbon unit.
- Butcher, Trevor W.,Hanna, Steven,Hartwig, John F.,Wills, Tyler
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p. 8736 - 8741
(2020/09/23)
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- Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydrofunctionalization and Formal Retro-hydrofunctionalization
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We report a contra-thermodynamic isomerization of internal olefins to terminal olefins driven by redox reactions and formation of Si-F bonds. This process involves chain-walking hydrosilylation of internal olefins and subsequent formal retro-hydrosilylation. The process rests upon the high activities of platinum hydrosilylation catalysts for isomerization of metal alkyl intermediates and a new, metal-free process for the conversion of alkylsilanes to alkenes. By this approach, 1,2-disubstituted and trisubstituted olefins are converted to terminal olefins.
- Hanna, Steven,Butcher, Trevor W.,Hartwig, John F.
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supporting information
p. 7129 - 7133
(2019/09/12)
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- 1,5-Naphthyl-linked bis(imino)pyridines as binucleating scaffolds for dicobalt ethylene oligo-/polymerization catalysts: Exploring temperature and steric effects
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Six examples of dinuclear bis(imino)pyridine-cobalt(ii) complexes, [1,5-{2-(CMeN)-6-(CMeN(2,6-R12-4-R2-C6H2))C5H3N}2(C10H6)]Co2Cl4 (R1 = Me, R2 = H Co1; R1 = Et, R2 = H Co2; R1 = iPr, R2 = H Co3; R1 = Me, R2 = Me Co4; R1 = Et, R2 = Me Co5; R1 = CHPh2, R2 = Me Co6), have been prepared from the corresponding bis(tridentate) compartmental ligands (L1-L6) in reasonable yields. The molecular structures of Co3 and Co5 revealed two N,N,N-cobalt dichloride units to adopt anti-positions about the 1,5-naphthyl linking unit, with each cobalt center exhibiting a distorted trigonal bipyramidal geometry. On activation with either MAO or MMAO, Co1-Co6 were shown to promote both polymerization and oligomerization of ethylene with high overall activities (up to 1.03 × 107 gPE per·mol(Co) per·h for Co1/MAO at 70 °C). Curiously, on increasing the reaction temperature a larger proportion of polymer was noted, while at lower temperature an enhanced selectivity for oligomer was seen. In general, the oligomeric products displayed Schulz-Flory distributions with high selectivities for α-olefins (>99%). On the other hand, the highly linear polymers displayed narrow dispersities and comprised both fully saturated and unsaturated chain ends with the vinyl content (-CHCH2) found to rise with the reaction temperature. By modulating the steric hindrance exerted by the ortho-R1 substituents in the precatalyst, polyethylenes displaying a remarkably broad range of molecular weights could be obtained [from 4.52 kg mol-1 (R1 = Me) to 246.7 kg mol-1 (R1 = CHPh2)].
- Chen, Qiang,Suo, Hongyi,Zhang, Wenjuan,Zhang, Randi,Solan, Gregory A.,Liang, Tongling,Sun, Wen-Hua
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supporting information
p. 8264 - 8278
(2019/06/18)
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- Re-catalyzed deoxydehydration of polyols to olefins using indoline reductants
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A rhenium (CH3ReO3, MTO) catalyzed deoxydehyradration (DODH) of glycols to alkenes has been achieved using hydroaromatic compounds as H-transfer reductants. Of the hydroaromatics examined, indoline was the most efficient and proved to be better potential hydrogen donor. The yield of the products is moderate to excellent and the reaction is very clean with the only indole, the oxidized byproduct of indoline detected.[Figure presented]
- Jefferson, Alana,Srivastava, Radhey S.
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p. 268 - 271
(2019/01/23)
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- Rhenium-catalyzed deoxydehydration of renewable biomass using sacrificial alcohol as reductant
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Catalytic deoxydehydration (DODH) of vicinal diols is studied. We find that NH4ReO4 (ammonium perrhenate, APR) catalyzes the DODH of glycols to alkenes by sacrificial alcohol (2,4-dimethyl-3-pentanol) at 140–165 °C. The product yields range from good to excellent and no isomers detected. The catalytic DODH reaction of glycols to alkene is of potential value for the production of chemicals and fuels from the renewable biomass-derived polyols.[Figure presented]
- Gossett, Justin,Srivastava, Radhey
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p. 3760 - 3763
(2017/09/09)
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- Direct β-Selective Cross-Coupling of Alkenyl Gold Complexes with Alkyl Electrophiles
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Alkenyl gold complexes are common intermediates in gold-catalyzed transformations of allenes and alkynes, and numerous methods for their functionalization have been explored. Particularly valuable are cross-coupling reactions, which result in the formation of a new C–C bond. Several strategies are known that enable α-selective cross-coupling of alkenyl gold complexes with aryl, allyl, or acyl coupling partners. We describe the direct β-selective cross-coupling of alkenyl gold complexes with simple alkyl electrophiles. We also describe the effects of the steric and electronic properties of alkenyl gold complexes on the selectivity of the cross-coupling reaction.
- Nguyen, Julia,Duncan, Nicole,Lalic, Gojko
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p. 5803 - 5806
(2016/12/18)
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- Photoinduced Charge-Transfer State of 4-Carbazolyl-3-(trifluoromethyl)benzoic Acid: Photophysical Property and Application to Reduction of Carbon?Halogen Bonds as a Sensitizer
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The photoinduced persistent intramolecular charge-transfer state of 4-carbazolyl-3-(trifluoromethyl)benzoic acid was confirmed. It showed a higher catalytic activity in terms of yield and selectivity in the photochemical reduction of alkyl halides compared to the parent carbazole. Even unactivated primary alkyl bromides could be reduced by this photocatalyst. The high catalytic activity is rationalized by considering the slower backward single-electron transfer owing to the spatial separation of the donor and acceptor subunits.
- Matsubara, Ryosuke,Shimada, Toshiyuki,Kobori, Yasuhiro,Yabuta, Tatsushi,Osakai, Toshiyuki,Hayashi, Masahiko
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supporting information
p. 2006 - 2010
(2016/07/28)
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- Synthesis of Pincer Hydrido Ruthenium Olefin Complexes for Catalytic Alkane Dehydrogenation
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A series of new hydrido Ru(II) olefin complexes supported by isopropyl-substituted pincer ligands have been synthesized and characterized. These complexes are thermally robust and active for catalytic transfer and acceptorless alkane dehydrogenation. Notably, the alkane dehydrogenation catalysts are tolerant of a number of polar functional species.
- Zhang, Yuxuan,Fang, Huaquan,Yao, Wubing,Leng, Xuebing,Huang, Zheng
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supporting information
p. 181 - 188
(2016/02/05)
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- 2-Benzimidazol-6-pyrazol-pyridine Chromium(III) Trichlorides: Synthesis, Characterization, and Application for Ethylene Oligomerization and Polymerization
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A series of chromium(III) complexes, LCrCl3 (Cr1-Cr4: L = 2-(N-R2-benzimidazol-2-yl)-6-(3,5-R1-pyrazol-1-yl)pyridine; Cr1: R1 = H, R2 = H; Cr2: R1 = Me, R2 = H; Cr3: R1 = Me, R2 = Me; Cr4: R1 = Me, R2 = Bn), were synthesized and characterized by IR spectroscopy and elemental analysis. The studies of the solid state of Cr2 and Cr3 revealed distorted octahedral geometries around the chromium centers by X-ray diffractions. In the presence of MAO, Cr1-Cr4 exhibited high activities toward ethylene oligomerization (up to 2.17 × 106 g·mol-1(Cr)·h-1) and ethylene polymerization (up to 6.78 × 105 g·mol-1(Cr)·h-1). The oligomers were produced with high selectivity for α-olefins (>99%), confirmed by FT-IR and 13C NMR, and the distributions followed the Schulz-Flory equation. Various reaction parameters including the amount of cocatalyst, reaction temperature, and time were evaluated in detail, and it was evident that the title complexes had good thermal stability and the substituents on imidazole-N of the ligands dramatically impacted the catalytic activities as well as the distribution of the products.
- Luo, Wenlong,Li, Antai,Liu, Shaofeng,Ye, Hongqi,Li, Zhibo
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supporting information
p. 3045 - 3050
(2016/10/30)
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- cis-Semihydrogenation of alkynes with amine borane complexes catalyzed by gold nanoparticles under mild conditions
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Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.
- Vasilikogiannaki, Eleni,Titilas, Ioannis,Vassilikogiannakis, Georgios,Stratakis, Manolis
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supporting information
p. 2384 - 2387
(2015/02/05)
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- In Situ Spectroscopic Investigation of the Rhenium-Catalyzed Deoxydehydration of Vicinal Diols
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The mechanism of the CH3ReO3-catalyzed deoxydehydration of a vicinal diol to an alkene driven by oxidation of a secondary alcohol was investigated by time-resolved, in situ IR spectroscopy and was found to occur in three steps: 1) reduction of the catalytically active methyltrioxorhenium(VII) to a rhenium(V) complex (the rate-limiting step), 2) condensation of the diol and the rhenium(V) complex to a rhenium(V) diolate, and 3) extrusion of the alkene accompanied by oxidation of the Re center and thus regeneration of CH3ReO3. The reaction follows zero-order kinetics initially but, unexpectedly, accelerates towards the end, which is explained in terms of a deactivating pre-equilibrium, in which the catalytically active CH3ReO3 condenses reversibly with the diol to form an inactive rhenium(VII) diolate. This conclusion is supported by the direct observation of a catalytically inactive species as well as DFT calculations of the IR spectra of the relevant compounds.
- Dethlefsen, Johannes R.,Fristrup, Peter
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p. 1184 - 1196
(2015/04/14)
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- PROCESS FOR FUNCTIONALIZING BIOMASS USING MOLYBDENUM CATALYSTS
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The present invention concerns a process for converting biomass into useful organic building blocks for the chemical industry. The process involves the use of molybdenum catalysts of the formula Aa+a(MovXxR1yR2zR3e)a*3-, which may be readily prepared from industrial molybdenum compounds.
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Page/Page column 12
(2015/03/16)
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- Lewis acid triggered reactivity of a lewis base stabilized scandium-terminal imido complex: C-H bond activation, cycloaddition, and dehydrofluorination
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A stable scandium-terminal imido complex is activated by borane to form an unsaturated terminal imido complex by removing the coordinated Lewis base, 4-(dimethylamino)pyridine, from the metal center. The ensuing terminal imido intermediate can exist as a
- Chu, Jiaxiang,Han, Xianghao,Kefalidis, Christos E.,Zhou, Jiliang,Maron, Laurent,Leng, Xuebing,Chen, Yaofeng
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supporting information
p. 10894 - 10897
(2014/08/18)
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- Investigation of hydrocarbon generation mechanism by polarizing the carboxy-group of fatty acid salt with microwave radiation
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Triglycerides can be converted to renewable hydrocarbons fuel which can be used as engine fuels by alkali pyrolysis decarboxylation and cracking processes. The purpose of present study was to explore decarboxylation mechanism of fatty acid salt with microwave radiation. Sodium stearate, potassium stearate, sodium oleate and sodium laurate was chosen as a model compound. The carboxy-terminal of this dipolar molecule was further polarized with microwave radiation. The Lorentz force of ions of dipolar molecules were moved in accordance with the way of electromagnetic waves, contribute to the formation of carbanion, which effectively promote the decarboxylation reaction. Moreover, the polarity of carboxy-terminal was stronger, more easily decarboxylation. The surface of glycerol formed a High-Temperature Locus in microwave radiation reaction system, facilitate the decarboxylation processe, in adition to played a role as the hydrogen donor for this high dielectric value compound. C8-C20 n-alkanes and n-alk-1-enes were arranged regular in liquid products. It proved the feasibility to derive renewable hydrocarbon fuel from sodium salt of fatty acids by microwave pyrolysis.
- Wang,Liu,Ruan,Wen,Wan,Zhang
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p. 369 - 375
(2014/06/09)
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- Oxorhenium-catalyzed deoxydehydration of glycols and epoxides
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The conversion of renewable cellulosic biomass into hydrocarbons has attracted significant attention with a growing demand of sustainability. MeReO3 catalyzes the deoxydehydration (DODH) of glycols and epoxides to alkenes by primary and secondary alcohols (5-nonanol, 3-octanol, 1-butanol) in the benzene solvent. The product yield range from moderate to excellent.
- Davis, Jacqkis,Srivastava, Radhey S.
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supporting information
p. 4178 - 4180
(2014/07/22)
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- METHOD FOR PRODUCING ALPHA-OLEFIN
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Provided is a production process for α-olefin which does not comply the Shultz-Flory distribution and which is excellent in the yields of α-olefins of 1-hexene up to 1-tetradecene each having 6 to 14 carbon atoms, particularly a yield of 1-octene. The above production process is characterized by polymerizing ethylene using (A) a specific chromium compound, (B) a specific aminophosphine ligand compound and (C) a promoter.
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Paragraph 0064
(2015/01/06)
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- Deoxydehydration of glycols catalyzed by carbon-supported perrhenate
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Support group: The first heterogeneous catalyst for the deoxydehydration (DODH) of glycols into olefins is reported. A carbon-supported perrhenate material was found to catalyze the reductive conversions of styrene diol, tetradecane diol, and diethyl tartrate into their respective olefins with high chemo-, regio-, and stereoselectivity. Effective reductants for this DODH reaction include H2, alcohols, and tetralin. Copyright
- Denning, Alana L.,Dang, Huong,Liu, Zhimin,Nicholas, Kenneth M.,Jentoft, Friederike C.
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p. 3567 - 3570
(2014/01/06)
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- Vanadium-catalyzed deoxydehydration of glycols
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A survey of several metavandate (VO3-) and chelated dioxovanadium derivatives shows that tetrabutylammonium dioxovanadium(v) dipicolinate most effectively catalyzes the deoxydehydration (DODH) of glycols to olefins in moderate to excellent yields with triphenylphosphine or sodium sulfite as reductants.
- Chapman Jr., Garry,Nicholas, Kenneth M.
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supporting information
p. 8199 - 8201
(2013/09/12)
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- Aminophosphine-based chromium catalysts for selective ethylene tetramerization
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Chromium complexes of three new ligands, Ph2PN(Me)(CH 2)2-X [X = NMe2(PNN); PPh2 (PNP); Py (PNPy)], have been examined vis-a-vis their ability to promote ethylene tetramerization, (PNN)CrCl3(L) [L = THF (1); CH3CN (2)], (PNPy)CrCl3(L) [L = THF (3); CH3CN (4)], and (PNP)CrCl3(THF) (5). In the case of 2 and 4, it was possible to grow crystals suitable for X-ray diffraction. The reaction of 3 with Et3Al afforded the dinuclear [(HN(Me)(CH2)2Py)CrCl 2Et]2 (6) containing a trivalent chromium connected to an Et group. During the alkylation though, the ligand has been fragmented with removal of the side arm and protonation of the N atom of the remaining NP residue. All the complexes have been tested for ethylene oligomerization activity. Complex 1 displayed the highest selectivity for 1-octene, upon activation with DMAO in MeCy. Contrary to expectations, complex 6 is not a self-activating catalyst.
- Shaikh, Yacoob,Gurnham, Joanna,Albahily, Khalid,Gambarotta, Sandro,Korobkov, Ilia
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p. 7427 - 7433,7
(2020/10/15)
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- Iron-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to α-olefins
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The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity. The Royal Society of Chemistry 2012.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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scheme or table
p. 2552 - 2554
(2012/03/26)
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- Direct arylation/alkylation/magnesiation of benzyl alcohols in the presence of grignard reagents via Ni-, Fe-, or Co-catalyzed sp3 C-O Bond activation
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Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp3 C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of nhexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.
- Yu, Da-Gang,Wang, Xin,Zhu, Ru-Yi,Luo, Shuang,Zhang, Xiao-Bo,Wang, Bi-Qin,Wang, Lei,Shi, Zhang-Jie
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supporting information
p. 14638 - 14641
(2012/11/07)
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- Photochemical method for producing hydrocarbons
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The present invention relates to a method of using radiation and (in one embodiment) solar energy and UV radiation to convert natural products, for example derivatives of vegetable oils, to lower molecular weight hydrocarbons. The invention further relates to a process whereby these hydrocarbons can be converted to vinyl monomers and used in the formation of plastics, solvents, fuels and the like.
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Page/Page column 9
(2012/02/14)
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- Highly active ethylene oligomerization catalysts
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Reaction of RN(H)PBr(Ph)2N(H)R [R = t-Bu, i-Pr, Ph] with two equivalents of n-BuLi followed by reaction with CrCl2(THF) 2 afforded the divalent chromium complexes [(t-Bu)NP(Ph) 2N(t-Bu)]Cr(μ2-Cl)2Li(THF)2 (1), [(i-Pr)NP(Ph)2N(i-Pr)]Cr(μ2-Cl)2Li(THF) 2 (2), and [{[(Ph)NP(Ph)2N(Ph)]Cr}2(μ 2-Cl)3][Li(DME)3] (3). The trivalent analogue of 1, {[(t-Bu)NP(Ph)2N(t-Bu)]Cr(μ2-Cl) 3(μ3-Cl)2}{Li (THF)2} (4), was obtained in a similar manner via treatment of the double deprotonated ligand with CrCl3(THF)3. Both reactions of the divalent1 or trivalent4 with AlMe3 yielded the trivalent and cationic complex {[(t-Bu)NP(Ph)2N(t-Bu)]2Cr}{(Me3Al) 2Cl}?toluene (5). Upon activation with MAO, 1-3 produced unprecedented and potentially useful catalytic systems for nonselective ethylene oligomerization devoid of polymer. Divalent chromium is clearly the species responsible for the catalytic behavior, ruling out that nonselective oligomerization proceeds via a redox metallacycle mechanism. The absence of polymer in combination with the record activity makes 1 competitive with the best performing industrially used systems.
- Albahily, Khalid,Licciulli, Sebastiano,Gambarotta, Sandro,Korobkov, Ilia,Chevalier, Reynald,Schuhen, Kathrine,Duchateau, Robbert
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experimental part
p. 3346 - 3352
(2011/09/12)
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- Ethylene oligomerization promoted by a silylated-SNS chromium system
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The ethylene trimerization SNS ligand has been modified by replacing the methylene carbons flanking the nitrogen atom with dimethyl silyl groups. Three ligands, CySCH2Si(CH3)2N(H)Si(CH 3)2CH2SCy (a), (t-Bu)SCH2Si(CH 3)2N(H)Si(CH3)2CH2S(t-Bu) (b), and PhSCH2Si(CH3)2N(H)Si(CH 3)2CH2SPh (c), have been prepared. Ligand a in either protonated or deprotonated forms was reacted with CrCl 3(THF)3 to afford the corresponding monomeric [CySCH 2Si(CH3)2N(H)Si(CH3) 2CH2SCy]CrCl3 (1a) or dimeric {[CySCH 2Si(CH3)2NSi(CH3)2CH 2SCy]CrCl(μ-Cl)}2 (2a). One-pot reaction of a in the presence of Et2AlCl with either Cr(III) or Cr(II) chlorides afforded in either case the divalent {[CySCH2Si(CH3) 2N(H)Si(CH3)2CH2SCy]Cr{(μ-Cl) Al(CH2CH3)2Cl}2 (3a). To deprotonate the N-H function of the Si-SNS ligand, n-BuLi was used for the purpose of preparing the divalent chromium analogue. The reaction afforded in the case of both a and b the two nearly isostructural divalent complexes {[CySCH 2Si(CH3)2NSi(CH3)2CH 2SCy]Cr(μ-Cl)}2 (4a) and {[(t-Bu)SCH 2Si(CH3)2NSi(CH3)2CH 2S(t-Bu)]Cr(μ-Cl)}2 (4b) in crystalline form. To further clarify the interaction of 4 with aluminate species, we have carried out in situ complexation in the presence of either AlCl3 or AlMe 3 and using divalent instead of trivalent chromium salts. In the cases of ligands a and c and AlCl3, two isostructural complexes, {[CySCH2Si(CH3)2N(H)Si(CH3) 2CH2SCy]Cr{(μ-Cl)AlCl3}2 (5a) and {[PhSCH2Si(CH3)2N(H)Si(CH3) 2CH2SPh]C{(μ-Cl)AlCl3}2 (5c), have been obtained. The reaction with AlMe3 afforded {[CySCH 2Si(CH3)2N(Al(CH3) 2-μ-Cl)Si(CH3)2CH2SCy]Cr{(μ- Cl)Al(CH3)3} (6a). Its structure was informative, showing a possible catalyst deactivation pathway. To better evaluate the role of the N-H function, we have also methylated ligand a at the N atom. The complexation to chromium was successful only in the presence of Me2AlCl and if a divalent chromium precursor was used. The reaction afforded the catalytically inactive divalent {[CySCH2Si(CH3)2N(CH 3)Si(CH3)2CH2SCy]Cr(μ-Cl)} 2{(Al(CH3)2Cl)2)(μ-Cl)} 2 (7d). Most of these species showed good catalytic activity upon activation but produced only statistical distributions of oligomers.
- Albahily, Khalid,Gambarotta, Sandro,Duchateau, Robbert
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experimental part
p. 4655 - 4664
(2011/11/07)
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- Synthesis and ethylene trimerisation capability of new chromium(II) and chromium(III) heteroscorpionate complexes
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Reaction of (Me2pz)2CHSiMe2N(H)R (R = iPr or Ph) or (Me2pz)2CHSiMe 2NMe2 with CrCl3(THF)3 or CrCl 2(THF)2 gave Cr{(Me2pz)2CHSiMe 2NR1R2}Cl3 (R1 = H, R2 = iPr (10) or Ph (11); R1 = R2 = Me (15)) or Cr{(Me2pz)2CHSiMe2NR 1R2}Cl2(THF) (R1 = H, R2 = iPr (12) or Ph (13); R1 = R2 = Me (16)), respectively. Compounds 10 and 11 were crystallographically characterized and the magnetic behaviour of all the new compounds was evaluated using SQUID magnetometry. Reaction of CrCl3(THF)3 with Li{C(Me 2pz)3}(THF) gave the zwitterionic complex Cr{C(Me 2pz)3}Cl2(THF) (17) containing an apical carbanion. Reaction of the analogous phenol-based ligand (Me2pz) 2CHArOH (ArO = 2-O-3,5-C6H2tBu 2) with CrCl3(THF)3 gave Cr{(Me 2pz)2CHArOH}Cl3 (19) whereas the corresponding reaction with CrCl2(THF)2 unexpectedly gave the Cr(iii) phenolate derivative Cr{(Me2pz)2CHArO}Cl2(THF) (20) which could also be prepared from CrCl3(THF)3 and the sodiated ligand [Na{(Me2pz)2CHArO}(THF)]2. Reaction of the corresponding ether (Me2pz)2CHArOMe with CrCl3(THF)3 or CrCl2(THF)2 gave Cr{(Me2pz)2CHArOMe}Cl3 (23) and Cr{(Me 2pz)2CHArOMe}Cl2(THF) (24), respectively. The catalytic performance in ethylene oligomerisation/polymerisation of all of the new Cr(ii) and Cr(iii) complexes was evaluated. Most of the complexes showed high activity, but produced a Schultz-Flory distribution of α-olefins. Compound 23 had an exceptionally low α-value of 0.37 and showed a preference for 1-hexene and 1-octene formation. While replacing a secondary amine (10-13) for a tertiary amine (15-16) resulted in loss of catalytic activity, replacing a phenol (19) for an anisole (23) group afforded a more selective and more active catalyst. Changing from MAO to DIBAL-O as cocatalyst induced a switch in selectivity to ethylene polymerisation.
- Kilpatrick, Alexander F. R.,Kulangara, Shaneesh Vadake,Cushion, Michael G.,Duchateau, Robbert,Mountford, Philip
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experimental part
p. 3653 - 3664
(2010/06/18)
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- Rhenium-catalyzed didehydroxylation of vicinal diols to alkenes using a simple alcohol as a reducing agent
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A new method for the catalytic didehydroxylation of vicinal diols is described. Employing a readily available low-valent rhenium carbonyl complex and a simple alcohol as a reducing agent, both terminal and internal vicinal diols are deoxygenated to olefins in good yield. The optional addition of acid (TsOH, H2SO4) provides access to lower reaction temperatures. This new system enables the transformation of a four-carbon sugar polyol into an oxygen-reduced compound, providing promising evidence for its practical application to produce unsaturated compounds from biomass-derived materials.
- Arceo, Elena,Ellman, Jonathan A.,Bergman, Robert G.
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supporting information; experimental part
p. 11408 - 11409
(2010/10/03)
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- Weakening C-O bonds: Ti(III), a new reagent for alcohol deoxygenation and carbonyl coupling olefination
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Investigations detailed herein, including density functional theory (DFT) calculations, demonstrate that the formation of either alkoxy- or hydroxy-Ti(III) complexes considerably decreases the energy of activation for C-O bond homolysis. As a consequence of this observation, we described two new synthetic applications of Nugent's reagent in organic chemistry. The first of these applications is an one-step methodology for deoxygenation-reduction of alcohols, including benzylic and allylic alcohols and 1,2-dihydroxy compounds. Additionally, we have also proved that Ti(III) is capable of mediating carbonyl coupling-olefination. In this sense, and despite the fact that for over 35 years it has been widely accepted that either Ti(II) or Ti(0) was the active species in the reductive process of the McMurry reaction, the mechanistic evidence presented proves the involvement of Ti(III) pinacolates in the deoxygenation step of the herein described Nugent's reagent-mediated McMurry olefination. This observation sheds some light on probably one of the mechanistically more complex transformations in organic chemistry. Finally, we have also proved that both of these processes can be performed catalytically in Cp 2TiCl2 by using trimethylsilyl chloride (TMSCl) as the final oxygen trap.
- Dieguez, Horacio R.,Lopez, Armando,Domingo, Victoriano,Arteaga, Jesus F.,Dobado, Jose A.,Herrador, M. Mar,Quilez Del Moral, Jose F.,Barrero, Alejandro F.
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supporting information; experimental part
p. 254 - 259
(2010/03/25)
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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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supporting information; experimental part
p. 3889 - 3899
(2009/12/26)
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- PROCESS FOR PRODUCING OLEFIN OLIGOMER
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A process for producing an olefin oligomer, which comprises the steps of (1) contacting a transition metal compound with a compound represented by the formula, R1R2A-G-AR3R4, to produce a contact product (i), (2) contacting an alumoxane compound with an organoaluminum compound to produce a contact product (ii), and (3) contacting the contact product (i), the contact product (ii), and an olefin with one another, wherein A is a nitrogen atom, a phosphorus atom, an arsenic atom or an antimony atom; G is a divalent group; and R1, R2, R3 and R4 are independently of one another a hydrocarbyl group, a halogenated hydrocarbyl group, an oxygen-containing hydrocarbyl group, a sulfur-containing hydrocarbyl group, a selenium-containing hydrocarbyl group, or a tellurium-containing hydrocarbyl group.
- -
-
Page/Page column 8-9
(2008/06/13)
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- A general and convenient method for the rhodium-catalyzed decarbonylation of aldehydes
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A practical protocol for the decarbonylation of a wide range of aldehydes has been developed by using commercially available RhCl3· SH2O and dppp in a diglyme solution. This method gives rise to decarbonylated products in good to high yield and is particularly useful because of its experimental simplicity, high generality and excellent level of functional group tolerance. The reaction has been applied in a tandem Oppenauer oxidation-decarbonylation sequence, which removes a hydroxymethyl group in one operation.
- Kreis, Michael,Palmelund, Anders,Bunch, Lennart,Madsen, Robert
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p. 2148 - 2154
(2007/10/03)
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- PROCESS FOR PRODUCING OLEFIN OLIGOMER
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A process for producing an olefin oligomer, which comprises the steps of (1) contacting an olefin with an organoaluminum compound to produce a contact product (i), (2) contacting a transition metal compound with a compound represented by the formula, R1R2A—G—AR3R4, to produce a contact product (ii), and (3) contacting the contact product (i), the contact product (ii), an alumoxane compound, and optionally an olefin with one another, wherein A is a nitrogen atom, a phosphorus atom, an arsenic atom or an antimony atom, and As are the same as or different from each other; G is a divalent group; and R1, R2, R3 and R4 are independently of one another a hydrocarbyl group, a halogenated hydrocarbyl group, an oxygen-containing hydrocarbyl group, a sulfur-containing hydrocarbyl group, a selenium-containing hydrocarbyl group, or a tellurium-containing hydrocarbyl group.
- -
-
Page/Page column 6-7
(2010/11/25)
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- METHOD FOR DEHYDRATING FATTY ALCOHOLS
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The invention relates to a method for producing hydrocarbons by dehydrating primary alcohols during which trifluoromethane sulfonic acid is used as a dehydration catalyst.
- -
-
Page/Page column 5
(2008/06/13)
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- METHOD FOR THE SYNTHESIS OF QUATERNARY AMMONIUM COMPOUNDS AND COMPOSITIONS THEREOF
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A novel manufacturing process is described for producing quaternary ammonium compounds having a selected anion, which may be useful in wood preservative formulations. The process involves reacting a trialkylamine with an alkyl bromide to form a quaternary tetraalkylammonium bromide salt, converting the quaternary tetraalkylammonium bromide salt to a quaternary tetraalkylammonium hydroxide salt by using an ion exchange resin, and converting the quaternary tetraalkylammonium hydroxide salt to the quaternary tetraalkylammonium salt of the selected anion.
- -
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Page/Page column 49-50; 59-60
(2008/06/13)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- 'Propylene spaced' allyl tin reagents: A new class of fluorous tin reagents for allylations under radical and metal-catalyzed conditions
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A new generation of propylene-spaced fluorous allyltin reagents [(Rf(CH2)3)3SnCH2CH=CH2] is described. These succeed in radical allylations where their lower homologs (ethylene-spaced) fail, and they provide improved performance in transition metal catalyzed allylations. The reagents and byproducts are readily separated by simple fluorous-organic liquid-liquid or solid-liquid extractions.
- Curran, Dennis P.,Luo, Zhiyong,Degenkolb, Peter
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p. 2403 - 2408
(2007/10/03)
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- Scope and utility of a new soluble copper catalyst [CuBr-LiSPh-LiBr-THF]: A comparison with other copper catalysts in their ability to couple one equivalent of a Grignard reagent with an alkyl sulfonate
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A mixture of equal amounts of CuBr-SMe2, LiBr, and LiSPh in THF at 0°C furnished a new soluble copper catalyst that was highly efficient at coupling primary, secondary, tertiary, aryl, vinyl, and allylic Grignard reagents to primary tosylates and primary Grignard reagents to secondary tosylates and mesylates, all with the use of only 1 equiv of Grignard reagent. The new catalyst was shown to be much more reactive than copper catalysts CuBr and Li2CuCl4 and more efficient in the transference of secondary and tertiary alkyl groups than lower order cuprates (Gilman reagents) and demonstrated more reactivity than the lower order cuprates with its ability to couple primary Grignard reagents to secondary sulfonates. The Grignard reagent/catalyst system was compatible with an ester functionalized tosylate, thus proving to be more chemoselective than a Grignard reagent without the catalyst. The catalyst exhibited good reactivity below room temperature, and with the addition of 6% v/v of HMPA to the catalyst solution, excellent yields of coupled product were obtained within a 25-67°C temperature range. 1H NMR demonstrated that the catalyst solution consisted of several species that most likely were composed of copper ligated with thiophenol, THF, and LiBr in aggregated forms.
- Burns, Dennis H.,Miller, Jeffrey D.,Chan, Ho-Kit,Delaney, Michael O.
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p. 2125 - 2133
(2007/10/03)
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- Intramolecular O-H...O-Ni and N-H...O-Ni Hydrogen Bonding in Nickel Diphenylphosphinoenolate Phenyl Complexes: Role in Catalytic Ethene Oligomerisation; Crystal Structure of (o-C6H4NHPh)>(PPh3)>
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Nickel diphenylphosphinoenolate complexes are prepared from ortho-HX-substituted phenacylidenetriphenylphosphoranes (X = O, NMe, NPh) which display strong intramolecular hydrogen bonding between the enolate oxygen and the H-X function; this feature dramat
- Braunstein, Pierre,Chauvin, Yves,Mercier, Sophie,Saussine, Lucien,Cian, Andre De,Fischer, Jean
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p. 2203 - 2204
(2007/10/02)
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- Compatibility studies of dimethyl(phenyl)silyl group as a masked hydroxyl group in compounds containing cyclopropane rings and in compounds containing the enone functionality
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Compatibility of the phenyl(dimethyl)silyl group as a masked hydroxyl group in the presence of cyclopropane rings and the enone functionality was studied. The result showed that conditions for the silyl-to-hydroxyl group conversion is not compatible with cyclopropane rings. However, under a modified two-step transformation procedure, the silyl group is converted to a hydroxyl group in the presence of an enone group without disturbing the carbon-carbon double bond, to a certain extent.
- Rahman,Fleming
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p. 1583 - 1594
(2007/10/02)
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- Telluroxide Elimination by Oxidation of Alkyl Aryl Tellurides: Remarkable Effect of Added Triethylamine
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Treatment of various alkyl phenyl tellurides with 1-2 mol equiv. of m-chloroperbenzoic acid in diethyl ether in the presence of triethylamine at 25 deg C for 2 h affords the corresponding alkenes highly selectively in fair to good yields.From stereochemical studies using erythro- and threo-phenyl 3-phenylbutan-2-yl tellurides as substrates it was revealed that although Et3N partly faciliates E2 elimination of the telluroxide, the main reaction course is the telluroxide syn-elimination (Ei elimination).Without the addition of Et3N the elimination was quite slow in many cases, and in fact the compounds derived from the addition of m-chlorobenzoic acid to tetradecyl and cyclohexyl phenyl telluroxides were isolated, the pyrolysis (ca. 250 deg C) of which afforded tetradec-1-ene and cyclohexene, respectively.A 2-pyridyltelluro moiety was revealed for the first time to be a better leaving group than a phenyltelluro moiety in telluroxide elimination.
- Nishibayashi, Yoshiaki,Komatsu, Naoki,Ohe, Kouichi,Uemura, Sakae
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p. 1133 - 1138
(2007/10/02)
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- Investigation of the modes of solubilization and norrish II photoreactivity of 2- and sym-n-alkanones in the solid phases of n-heneicosane and two homologues
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The nature of the solubilization sites and the solubility limits of a homologous series of 2- and sym-n-alkanones (2-N and m-N, respectively) have been investigated in the hexagonally and orthorhombically packed layered solid phases of heneicosane (C21) by differential scanning calorimetry, deuterium magnetic resonance, and optical microscopy. The photoselectivity and relative quantum efficiencies of product formation from the alkanones in the same solid phases were determined. Results from experiments employing the solid phases of eicosane (C20) and hexacosane (C26) were also obtained. The data show that the solid phases of n-alkanes impose severe restrictions on the motions of the alkanones and their photochemically-generated hydroxy-1,4-biradical intermediates only when the solutes fit well within a solvent layer. In those cases, extremely large photoselectivities, larger than those from analogous smectic liquid-crystalline phases, can be achieved. However, the ability of a solid n-alkane phase to incorporate an alkanone of a different length is much more limited than in the smectic phases. Eutectic mixtures and phase-separated alkanone crystals are obtained in many of the systems investigated.
- Nu?ez, Alberto,Hammond, George S.,Weiss, Richard G.
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p. 10258 - 10271
(2007/10/02)
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- SYNTHESE ET ETUDE DE LA DEGRADATION PHOTOCHIMIQUE DE TENSIO-ACTIFS CATIONIQUES PHOTOCLIVABLES
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A homologous series of photocleavable cationic surfactants was prepared.These aryl-alkyl-ketone type surfactants have the following structure .Their critical micelle concentration in water was determined.The photodegradation study has shown that the cleavage occurs with a high quantum yield by a Norrish II mechanism with formation of alkene, substituted acetophenone and cyclobutanols.The photochemical yield of cleavage reaches 75 percent with formation of a hydrophilic (substituted acetophenone) and a hydrophobic derivative (alkene).
- Strub-Leconte, M. P.,Riess, G.
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p. 137 - 144
(2007/10/02)
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