- A Sygmatropic Hydrogen Shift Induced by High Vibrational Overtone Excitation: The Isomerization of 2-Methylcyclopentadiene
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Laser excitation of high CH stretching overtone transitions has been used to induce the isomerization of 2-methylcyclopentadiene to 1-methylcyclopentadiene.The reaction is a sigmatropic hydrogen shift and therefore the reaction coordinate involves significant hydrogen atom motion.This provides a reasonable experimental test for the possibility that overtone excitation of CH stretching motions may lead to enhanced unimolecular reaction rates if there is strong coupling between the reaction coordinate and the nuclear motions which are excited by photon absorption.Values of the unimolecular reaction rate constant, k(E), have been deduced from photochemical quantum yields for excitation of the methylenic, methyl, and olefinic fourth CH stretching overtone transitions of 2-methylcyclopentadiene.No rate enhancement is observed for excitation of the methylenic transition compared to the methyl or olefinic trannsitions.The values of k(E) scale only with total energy and are in reasonable agreement with values calculated from RRKM theory.
- Jasinski, Joseph M.,Frisoli, Joan K.,Moore, C. Bradley
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Read Online
- Effect of acidic properties of mesoporous zeolites supporting Pt nanoparticles on hydrogenative conversion of methylcyclopentane
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The effect of acidic properties of mesoporous zeolites on the control of product selectivity during the hydrogenative isomerization of methylcyclopentane has been investigated. A series of mesoporous zeolites with controlled acidic properties were prepared by postdealumination process with hydrochloric acid under hydrothermal conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs) with a mean size of 2.5 nm (±0.6 nm). As compared to the pure Pt NPs supported on catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce isomers most selectively (~80%), the Pt NPs supported on mesoporous zeolites produced C6-cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Br?nsted (B) and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of pyridine and NH3 temperature-programmed desorption measurements, and they are correlated with the selectivity change between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Br?nsted acid sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L ratio is effective for the cyclohexane formation, whereas more Br?nsted acidic zeolite having relatively larger B/L ratio is effective for the benzene formation.
- Na, Kyungsu,Alayoglu, Selim,Ye, Rong,Somorjai, Gabor A.
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supporting information
p. 17207 - 17212
(2015/02/19)
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- Synthesis of isoprene from formaldehyde and isobutene over phosphate catalysts
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Vapor phase Prins condensation of isobutene with formaldehyde has been studied over boron (BP), aluminum (AlP), titanium (TiP), zirconium (ZrP) and niobium (NbP) phosphates. The catalysts were characterized by elemental analysis, X-ray diffraction, low-te
- Sushkevich,Ordomsky,Ivanova
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- Solvent-free conversion of linalool to methylcyclopentadiene dimers: A route to renewable high-density fuels
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Neat biofuel in HD: Linalool, a linear terpene alcohol, can be selectively converted by ruthenium metathesis catalysts under solvent-free conditions to 1-methyl-cyclopent-2-enol and isobutylene in quantitative yield. Dehydration of the alcohol under mild conditions followed by low-temperature thermal dimerization yields methylcyclopentadiene dimer, which can be readily converted into a high-density fuel.
- Meylemans, Heather A.,Quintana, Roxanne L.,Goldsmith, Bryan R.,Harvey, Benjamin G.
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experimental part
p. 465 - 469
(2012/02/14)
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- Removal of alcohols and water from a methylcyclopentadiene recycle stream in a process for the synthesis of methylcyclopentadienyl manganese tricarbonyl
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During the process of synthesis of methylcyclopentadienyl manganese tricarbonyl (MMT), a key raw material methylcyclopentadiene (MCP) is used. The MCP component may be recycled for subsequent reaction processes. The recycle stream of MCP is washed with water and, optionally, passed over a molecular sieve bed to remove the contaminants protic side products from the MCP recycled stream.
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Page/Page column 3
(2008/06/13)
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- Process for producing cyclopentadiene or derivatives thereof and apparatus for the same, and process for producing metallocenes or derivatives thereof
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The present invention provides a process for producing cyclopentadiene or a derivative thereof by heating a mixture containing at least one of dicyclopentadiene or a derivative thereof, the process comprising: a first step comprising heating the mixture into vapor; a second step comprising maintaining while heating the vapor at a temperature higher than the boiling point of the desired cyclopentadiene or derivative thereof to condense and remove high-boiling components and simultaneously collect residual vapor; and a third step comprising maintaining while heating the collected vapor at a temperature lower than the boiling point of the desired cyclopentadiene or derivative thereof to condense and collect the cyclopentadiene or derivative thereof. In the third step, the vapor may be contact with nitrogen gas to improve the yield of the cyclopentadiene or derivative thereof.
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- Pyrolysis and oxidation of anisole near 1000 K
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Experiments near 1000 K have revealed the thermal decomposition of anisole to proceed exclusively via homolysis of the O-CH3 bond. The anisole decay was observed to be first order even in the presence of oxygen. The distribution of reaction intermediates was virtually independent of equivalence ratio, φ ≡ ([anisole]/[O2])/([anisole]/[O2]) stoichiometric. Phenol, cresols, methylcyclopentadiene, and CO were major products. Minor species included benzene, cyclopentadiene, ethane, and methane. Trace yields of ethene, toluene, and naphthalenes were observed under all conditions; trace C2-C4 species including acetylene, allene, and 1,3-butadiene were observed only in the oxidation experiments. Oxidation occurs preferentially through methylcyclopentadiene. A multichannel reaction scheme is proposed involving the formation of a chemically activated adduct from phenoxy and methyl. The complex reacts to form primarily cresols and methylcyclopentadiene + CO either directly or subsequent to stabilization. A kinetic model for anisole pyrolysis has been developed to predict the disappearance of anisole and the production of reaction intermediates. Excellent agreement is obtained between experimental data and model predictions of anisole, CO, methylcyclopentadiene, and total phenolics.
- Pecullan,Brezinsky,Glassman
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p. 3305 - 3316
(2007/10/03)
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- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
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- Stereoselection in Thermal Asymmetric Diels-Alder Reactions. Electronic vs Steric Effects
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Experimental evidence was found for an electronic contribution favoring the cisoid conformation of α,β-unsaturated carbonyl compounds in thermal Diels-Alder transition states.
- Stammen, Blanda,Berlage, Ulrich,Kindermann, Richard,Kaiser, Manfred,Guenther, Barbara,et al.
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p. 6566 - 6575
(2007/10/02)
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- On the Thermal Isomerization and Aromatization of Hex-1-ene-5-yne
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The gas phase conversion of hex-1-ene-5-yne induced by conventional hot-wall pyrolysis, very low pressure pyrolysis (VLPP-MS technique) and continuous-wave CO2 laser-photosensitized (SF6) pyrolysis was studied at 350-1100 deg C.The pyrolysis experiments were performed in quartz reactors and the reaction products analyzed by capillary gas chromatography, mass and n.m.r. spectroscopy.The pattern of conversion suggested for all the processes involved a sequence of isomerizations ( -> hexa-1,2,5-triene -> methylcyclopentenes), aromatization (into benzene via pentafulvene) and C-C bond rupture (into propargyl and allyl radicals).The formation of benzene is explained by reaction network with methylenecyclopentenes and methylcyclopentadienes as key intermediates.
- Remmler, M.,Ondruschka, B.,Vorwerk, D.,Olk, B.,Pola, J.,Kubat, P.
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p. 699 - 709
(2007/10/02)
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- A Simple and Convenient Synthesis of 5-Alkyl-Substituted 3-Isopropenyl- and 3-Acetyltropolones
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2-Alkyl-substituted 6,6-dimethylfulvenes 3a-d, prepared by alkaline condensation of alkylcyclopentadienes 2a-d with acetone, react with dichloroketene to give 2-alkyl-substituted 7,7-dichloro-4-isopropylidenebicyclohept-2-en-6-ones 4a-d.The cycloadducts 4a-d are hydrolyzed in aqueous acetic acid in the presence of sodium acetate to give 5-alkyl-substituted 3-isopropenyltropolones (2-hydroxy-3-isopropenyl-2,4,6-cycloheptatrienones) 5a-d.These 3-isopropenyltropolones 5a-d are hydrogenated on 5percent palladium-charcoal to afford 5-alkyl-3-isopropyltropolones 6a-d andtreated with hydrazoic acid to give 5-alkyl-3-acetyltropolones 7a-d.
- Imafuku, Kimiaki,Arai, Kiyomi
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p. 501 - 505
(2007/10/02)
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- High-density fuel oil
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The present invention provided a high-density fuel oil comprising an isomerized product prepared by isomerizing an alicyclic saturated hydrocarbon represented by the following formula in the presence of an acid catalyst: STR1 wherein each of m and n is 0 or 1, and each of R1 to R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, but the number of the total carbons of R1 to R3 is within the range of 1 to 3.
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- Traction drive fluid
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A traction drive fluid comprising as a base stock at least one hydrocarbon selected from the group consisting of compounds of the following general formulae (I) to (V) STR1 wherein R1, R2 and R3, independently from each other, represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R4, R5, R6, R7, R8, R9 and R10, independently from each other, represent a hydrogen atom or a methyl group.
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- 66. The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage
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The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8.In contrast, porcine liver esterase (PLE, EC 3.1.1.1) cleanly hydrolyses 5 to give the isolable 1-methyl-2,4-cyclopentadiene-1-carboxylic acid (13).The latter undergoes thermal dimerization with conservation of the geminal-substitution pattern.The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C2 symmetry.Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acidic concentration is used.The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.
- Burger, Ulrich,Erne-Zellweger, Dominique,Mayerl, Christa
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p. 587 - 592
(2007/10/02)
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- High-density liquid fuel
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The present invention is connected with a high-density liquid fuel for rockets and jet engines which mainly comprises a compound represented by the general formula STR1 wherein each of m and n is 0 or 1, and each of R1 to R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, but a sum of R1 to R3 is an integer of 1 to 3.
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- Carbene Reactions, XVIII. Thermal Behaviour of 7-Alkylidenebicycloheptadiene Derivatives
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Thermolysis of 7-alkylidenenorbornadienes 2 results in a retro-Diels-Alder cleavage to fulvenes and acetylene.A different mode of cleavage - into benzene and a carbene - is observed with such derivatives of 2 which carry ?- or ?-donor functions at C-8.The dependence of the reaction pathways on the nature of the substituent at C-8 is discussed on the basis of MO-calculations.
- Hoffmann, Reinhard W.,Riemann, Achim,Mayer, Bernhard
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p. 2493 - 2513
(2007/10/02)
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- Chemistry of gem-Dihalocyclopropanes. XX. The Effect of Methyl and Phenyl Substituents on the Vinylcyclopropylidene-Cyclopentenylidene Rearrangement
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Reactions of gem-dibromocyclopropanes of the general structure 1 with methyllithium have been studied.In the most cases cyclopentadienes and/or vinylallenes are the products formed.The results obtained give evidence of a profound substituent effect on the carbene-carbene rearrangement leading to cyclopentadienes.We believe the effect is essentially steric in origin.The results support the mechanism proposed for the rearrangement.
- Holm, Kjetil H.,Skatteboel, Lars
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p. 783 - 794
(2007/10/02)
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- Carbene Rearrangements, X. 2-Vinylcyclobutylidene
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The Bamford-Stevens reaction of 2-vinylcyclobutanone tosylhydrazone sodium salt (13) has been studied with respect to the potential carbene-carbene rearrangement 3 -> 4. 2-Vinylcyclobutylidene (3) surprisingly undergoes exlusively carbene rearrangements.In 3 the cyclobutylidene-methylenecyclopropane rearrangements to 16 and 17 dominate.The 1,3-carbon migration of the divalent carbon is not observed.
- Brinker, Udo H.,Koenig, Lothar
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p. 882 - 893
(2007/10/02)
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