- The effect of reactor surfaces on single electron transfer reactions. The reaction of 1-iodo-2,2-dimethylhexane with lithium aluminum deuteride
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Reactions of 1-iodo-2,2-dimethylhexane (4) with LiAlD4 have been carried out in a variety of reaction vessels. In vessels of used pyrex, teflon, and stainless steel, the surface of the reactor plays a role in the product distribution. However, treated pyrex, new pyrex and quartz vessels yield consistent data that support single electron transfer as the major reaction pathway in the reduction of 4 LiAlD4.
- Ashby,Welder,Welder, Catherine O.
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Read Online
- Single Electron Transfer in the reaction of an alkyl iodide with LiAlH4 and LiAlD4 in the absence of a halogen atom radical chain process
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Reactions of the noncyclizable alkyl iodide, 1-iodo-2,2-dimethylhexane (9), with LiAlH4 and LiAlD4 have been carried out under a variety of conditions. Although the structure of 9 prohibits a halogen atom radical chain process, deuterium incorporation studies provide convincing evidence for single electron transfer (SET) as the major reaction pathway.
- Ashby,Welder, Catherine O.,Doctorovich, Fabio
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Read Online
- Production of Gasoline Fuel from Alga-Derived Botryococcene by Hydrogenolysis over Ceria-Supported Ruthenium Catalyst
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Hydrogenolysis of hydrogenated botryococcene (Hy-Bot) was conducted over various supported Ru catalysts, Ir/SiO2, and Pt/SiO2–Al2O3. Ru/CeO2 with very high dispersion showed the highest yield (70 %) of gasoline-range (C5–C12) alkanes at 513 K. The main gasoline-range products were dimethylalkanes. This yield is comparable to or higher than the gasoline yields from botryococcene in the literature, which were obtained at much higher temperature. Ir/SiO2 also showed a high fuel yield, but the activity was much lower than that with the Ru catalysts. The reaction over Pt/SiO2–Al2O3 slowed down before total conversion of Hy-Bot was achieved. Ru/CeO2 was stable in the hydrogenolysis of Hy-Bot without loss of activity and selectivity during reuses. The carbon balance was low for the hydrogenolysis of Hy-Bot over all catalysts if the main products are heavy hydrocarbons, whereas for the hydrogenolysis of squalane the carbon balance was kept near 100 %. 1H NMR spectra of the product mixture and thermogravimetric analyses of the product mixture and the recovered catalyst revealed that the formation of aromatic compounds, polymeric products, and coke was negligible for the carbon balance. In a model reaction using substrate compounds with a substructure of Hy-Bot, only 2,5-dimethylhexane, which has a C6 chain with two Cprimary?Ctertiary bonds, produced a cyclic product, 1,4-dimethylcyclohexane, which has a higher boiling point than the substrate. This dehydrocyclization reaction makes the product distribution in the hydrogenolysis of Hy-Bot more complex.
- Nakaji, Yosuke,Oya, Shin-Ichi,Watanabe, Hideo,Watanabe, Makoto M.,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
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p. 2701 - 2708
(2017/07/28)
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- IONIC LIQUID ALKYLATION OF 1-BUTENE TO PRODUCE 2,5-DIMETHYLHEXANE
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A process for producing dimethylhexanes (DMH) is provided. The DMH can be used to produce p-xylene. The process involves the alkylation of isobutane and 1-butene using an ionic liquid to produce naphtha that is rich in DMH. The DMH is then converted in high selectivity to xylene, including p-xylene, by dehydrocyclization.
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Page/Page column 17
(2015/09/23)
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- Reactivity of mixed organozinc and mixed organocopper reagents. Part 4: A kinetic study of group transfer selectivity in C-C coupling of mixed diorganocuprates
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The competitive rate data and Taft relationships for the coupling of bromomagnesium n-butyl (substituted phenyl) cuprates with alkyl bromides show that selective n-butyl transfer can be explained by an oxidative addition mechanism. Taft reaction constants
- Erdik, Ender,Oezkan, Duygu
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experimental part
p. 1148 - 1154
(2010/07/13)
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- METHOD OF PREPARING GTBE
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A process for glycerol etherification, comprising a recycle of glycerol and/or mono-ether, to produce glycerol alkyl ethers with low amount of mono-ether by reacting glycerol and olefinic hydrocarbon, and/or the corresponding aldehydes, ketones and alcohols, having 2 to 10 carbon atoms in the presence of homogeneous acid catalyst with hindered formation of olefin oligomers comprising of two essential steps: reaction step (1) neutralization and salt removal step (2).
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Page/Page column 8-9
(2009/12/28)
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- Alkene oligomerization process
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A process for oligomerising alkenes having from 3 to 6 carbon atoms which comprises contacting a feedstock comprising a) one or several alkenes having x carbon atoms, and, b) optionally, one or several alkenes having y carbon atoms, x and y being different, with a catalyst containing a zeolite of the MFS structure type, under conditions to obtain selectively oligomeric product containing predominant amounts of certain oligomers. The process is carried out at a temperature comprised between 125 and 175° C. when the feedstock contains only alkenes with 3 carbon atoms and between 140 and 240° C., preferably between 140 and 200° C. when the feedstock contains comprises at least one alkene with 4 or more carbon atoms.
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- Disproportionation of hydrocarbons
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A novel hydrocarbon disproportionation process is provided and includes contacting a hydrocarbon feed comprising at least one paraffin with a disproportionation catalyst comprising a support component, a metal, and a halogen in a disproportionation reaction zone under disproportionation reaction conditions.
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- Catalyst and process for contacting a hydrocarbon and ethylene
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A process of contacting at least one feed hydrocarbon, containing three to about seven carbon atoms per molecule, and ethylene in a hydrocarbon-containing fluid in the presence of a catalyst composition to provide at least one product hydrocarbon isomer containing about four to about nine carbon atoms per molecule is provided. The at least one feed hydrocarbon can be selected from paraffins, isoparaffins, and the like and combinations thereof. The catalyst composition contains a hydrogen halide component, a sulfone component, and a metal halide component.
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- Gas to liquid conversion process
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A process is disclosed for the conversion of lower molecular weight hydrocarbons, such as methane, into higher molecular weight hydrocarbon products, such as hydrocarbons having between 4 and 29 carbons. The process includes forming hydrated electrons, such as by mixing the lower molecular weight hydrocarbons with water and contacting the mixture with an energy source to form hydrated electrons. The hydrated electrons react with the methane to form hydrogen and higher molecular weight hydrocarbon products. Also disclosed is a related process for converting higher molecular weight hydrocarbons to lower molecular weight hydrocarbons by forming a mixture of higher molecular weight hydrocarbons and water and contacting the mixture with an energy source to form hydrated electrons that react with the higher molecular weight hydrocarbons to form hydrogen and lower molecular weight hydrocarbon products.
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Page column 3-4
(2008/06/13)
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- Effect of zeolite structure and acidity on the product selectivity and reaction mechanism for n-octane hydroisomerization and hydrocracking
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The activity, product selectivity, and stability of a series of bifunctional zeolite catalysts, primary ZSM-12, USY, and β-zeolite, with different Si/Al ratios were compared for the hydroisomerization and hydrocracking of n-octane. The performance of L-zeolite and mordenite was examined to a lesser extent as well. It was found that the activity per acidic site decreases at the initial stage (1 h on stream) in the following order: ZSM-12 > β-zeolite > mordenite > USY > L-zeolite. For extended periods of operation, the activity of ZSM-12 remains unchanged. The superior stability of ZSM-12 even under accelerating coking conditions results from its unique pore structure, which does not favor coke formation. Its one-dimensional noninterpenetrating puckered channels (5.5 × 6.1 A) act as perfect tubes, which do not trap coke precursors. The branched product selectivity increases with the increase in Bronsted acid site strength of the zeolite catalysts, and thus hydroisomerization is favored at the expense of cracking at a higher Bronsted acid strength. USY-5.8 (CBV-712) showed relatively high initial activity with respect to other USYs. This is probably related to its high surface Al content. The Bronsted acid strength of the USY zeolites decreases in the order USY-2.6 > USY-28 > USY-5.8. The 2,2-DMC6 and 3,3-DMC6 isomers are not favored as final products due to their bulky molecular size even in USY. In addition, the 2,2-DMC6 species is more abundant than 3,3-DMC6 because the rate of isomerization by PCP intermediates decreases in the following order: 2-MC7 > 3-MC7 > 4-MC7. The 2,3-DMC6 concentration is much higher than that predicted by equilibrium, which indicates that the interconversion of 2,3-DMC6 to other dibranched isomers is not preferred. The i-C4/n-C4 ratio detected depends on both the reaction temperature and zeolite pore structure/acidity. Aluminium content determines the type of β-scission. For zeolites with a high concentration of acid sites (Si/Ai about 30), type A β-scission dominates at low temperature, while at lower Al content, type A, B, and C β-scissions are equally important.
- Zhang, Wenmin,Smirniotis, Panagiotis G.
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p. 400 - 416
(2007/10/03)
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- Convincing Evidence, Not Involving Cyclizable Radical Probes, That the Reaction of LiAlH4 with Hindered Alkyl Iodides Proceeds Predominantly by a Single Electron Transfer Pathway
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Previous workers have maintained that evidence for the radical nature of the reaction of LiAlH4 with sterically hindered alkyl iodides is due to radical initiation by impurities followed by a halogen atom radical chain process involving the cyclizable alkyl iodide probe and that the reduction of the C-I bond actually proceeds by an SN2 pathway. In order to resolve the validity of this explanation, 1-iodo-2,2-dimethylhexane (the saturated counterpart of the cyclizable probe), which is not capable of this halogen atom radical chain process, was allowed to react with LiAlD4. The reduction product, 2,2-dimethylhexane, contained only 4-76% deuterium depending on the conditions of the reaction. This result is consistent with the reaction proceeding by a SET process via a radical intermediate and is inconsistent with an SN2 pathway. We have determined the influence of the nature of the reaction on the type of reactor surface (Pyrex, Teflon, stainless steel, and quartz) used in the reaction. We have also studied the influence of AlD3 (a byproduct in the reduction) in the mechanistic evaluation of this reaction.
- Ashby,Welder, Catherine O.
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p. 3542 - 3551
(2007/10/03)
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- Pt/SAPO-5 and Pt/SAPO-11 as Catalysts for the Hydroisomerization and Hydrocracking of n-Octane
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n-Octane hydroisomerization and hydrocracking on SAPO-5 and SAPO-11 catalysts containing 0.5 wt.percent Pt have been investigated in a flow reactor over a wide range of temperatures (573-708 K) and pressures (atmospheric, 3 and 5 bar).These studies have shown that hydroisomerization is a function of the total conversion.The primary products obtained with n-octane were the monobranched isomers.Multibranched feed isomers and cracked products were formed in subsequent reactions.In all cases, hydrogen pressure had a strong influence on the activity and time-on-stream deactivation.Hydroisomerization can be considered to be the primary reaction, with hydrocracking occurring to a significant extent only at higher conversions (>40percent for Pt/SAPO-5 and >65percent for Pt/SAPO-11).The selectivity patterns found in these molecular-sieve catalysts are interpreted in terms of a series of reaction pathways incorporating both confinement effects and shape selectivity factors.
- Campelo, J. M.,Lafont, F.,Marinas, J. M.
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p. 1551 - 1556
(2007/10/02)
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- Investigation of the Purity of Alkali Metal Diphenylphosphides and Their Reactions with Organic Halides. Evidence for Single Electron Transfer
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For the first time the purity of lithium, sodium, and potassium diphenylphosphide, prepared by various methods, has been evaluated using (31)P NMR spectroscopy.A method was developed to prepare each of the phosphides in a high state of purity.Highly pure potassium diphenylphosphide was then allowed to react with p-iodotoluene in order to determine the effect of purity on the SRN1 nature of this reaction.The results were then compared with literature reports which used less pure KPPh2.The mechanism of reaction of alkyl halides with pure alkali metal diphenylphosphides, using the radical probes 6-halo-5,5-dimethyl-1-hexenes and 1-halo-2,2-dimethylhexanes, was investigated.The results provide the first evidence to support single electron transfer (SET) in the reaction of an alkali metal diphenylphosphide with an alkyl halide.SET was found to be the major reaction pathway in the reaction of hindered alkyl iodides (neopentyl type).On the other hand, SET was found to be a minor pathway in the reaction of the corresponding alkyl bromides and chlorides with PPh2(1-).There was no evidence found for SET in the reactions of unhindered alkyl halides with PPh2(1-) although SET participation cannot be rigorously excluded.
- Ashby, E. C.,Gurumurthy, R.,Ridlehuber, R. W.
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p. 5832 - 5837
(2007/10/02)
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