- Kinetics of the thermal isomerization of 1,1,2,2-tetramethylcyclopropane
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Reaction rates for the structural isomerization of 1,1,2,2- tetramethylcyclopropane to 2,4-dimethyl-2-pentene have been measured over a wide temperature range, 672-750 K in a static reactor and 1000-1120 K in a single-pulse shock tube. The combined data from the two temperature regions give Arrhenius parameters Ea = 64.7 (±0.5) kcal/mol and log 10(A, s-1) = 15.47 (±0.13). These values lie at the upper end of the ranges of Ea and log A values (62.2-64.7 kcal/mol and 14.82-15.55. respectively) obtained from three previous experimental studies, each of which covered a narrower temperature range. The previously noted trend toward lower Ed values for structural isomerization of methylcyclopropanes as methyl substitution increases extends only through the dimethylcyclopropanes (1,1- and 1,2-); Ea then appears to increase with further methyl substitution. In contrast, the pre-exponential factors for isomerization of cyclopropane and all of the methylcyclopropanes through tetramethylcyclopropane lie within ±0.3 of log10(A,s -1) = 15.2 and show no particular trend with increasing substitution.
- Lewis, David K.,Gray, Timothy,Katsva, Vlad,Parcella, Kyle,Schlier, Jessica,Kalra, Bansi L.,Cho, Janet,Mish, Debra
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Read Online
- Decarbonylative Olefination of Aldehydes to Alkenes
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New atom-economical alternatives to Wittig chemistry are needed to construct olefins from carbonyl compounds, but none have been developed to-date. Here we report an atom-economical olefination of carbonyls via aldol-decarbonylative coupling of aldehydes using robust and recyclable supported Pd catalysts, producing only CO and H2O as waste. The reaction affords homocoupling of aliphatic aldehydes, as well as heterocoupling of aliphatic and aromatic ones. Computations provide insight into the selectivity and thermodynamics of the reaction. The tandem aldol-decarbonylation reaction opens the door to exploration of new carbonyl reactivity to construct olefins.
- Ainembabazi, Diana,Reid, Christopher,Chen, Amanda,An, Nan,Kostal, Jakub,Voutchkova-Kostal, Adelina
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supporting information
p. 696 - 699
(2020/01/31)
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- Alkanethiolate-capped palladium nanoparticles for selective catalytic hydrogenation of dienes and trienes
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Selective hydrogenation of dienes and trienes is an important process in the pharmaceutical and chemical industries. Our group previously reported that the thiosulfate protocol using a sodium S-alkylthiosulfate ligand could generate catalytically active Pd nanoparticles (PdNP) capped with a lower density of alkanethiolate ligands. This homogeneously soluble PdNP catalyst offers several advantages such as little contamination via Pd leaching and easy separation and recycling. In addition, the high activity of PdNP allows the reactions to be completed under mild conditions, at room temperature and atmospheric pressure. Herein, a PdNP catalyst capped with octanethiolate ligands (C8 PdNP) is investigated for the selective hydrogenation of conjugated dienes into monoenes. The strong influence of the thiolate ligands on the chemical and electronic properties of the Pd surface is confirmed by mechanistic studies and highly selective catalysis results. The studies also suggest two major routes for the conjugated diene hydrogenation: the 1,2-addition and 1,4-addition of hydrogen. The selectivity between two mono-hydrogenation products is controlled by the steric interaction of substrates and the thermodynamic stability of products. The catalytic hydrogenation of trienes also results in the almost quantitative formation of mono-hydrogenation products, the isolated dienes, from both ocimene and myrcene.
- Chen, Ting-An,Shon, Young-Seok
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p. 4823 - 4829
(2017/10/19)
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- DIARYL AMINE ANTIOXIDANTS PREPARED FROM BRANCHED OLEFINS
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Diaryl amines are selectively alkylated by reaction with branched olefins, which olefins are capable of forming tertiary carbonium ions and can be conveniently prepared from readily available branched alcohols. The diaryl amine products are effective antioxidants and often comprise a high amount of di-alkylated diaryl amines and a low amount of tri- and tetra-alkylated diaryl amines.
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Paragraph 0028; 0058; 0059
(2017/02/09)
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- Cross-linked polymer coated Pd nanocatalysts on SiO2 support: Very selective and stable catalysts for hydrogenation in supercritical CO 2
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Using greener solvents, enhancing the selectivity and stability of catalysts is an important aspect of green chemistry. In this work, we developed a route to immobilize Pd nanoparticles on the surface of silica particles with cross-linked polystyrene coating by one-step copolymerization, and Pd(0) nanocatalysts supported on the silica particle supports with cross-linked polystyrene coating were successfully prepared. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), plasma optical emission spectroscopy, and thermogravimetric analysis (TGA), and were used for hydrogenation of 2,4-dimethyl-1,3-pentadiene to produce 2,4-dimethyl-2-pentene and allyl alcohol to produce 1-propanol. It was found that the selectivity of the reaction was enhanced significantly by the polymer coating, and the catalysts were very stable due to the insoluble nature of the cross-linked polymers. Supercritical (sc)CO2 can accelerate the reaction rates of the reactions catalyzed by the specially designed catalysts significantly. The excellent combination of polymer coating and scCO2 has wide potential applications in catalysis.
- Wu, Tianbin,Jiang, Tao,Hu, Baoji,Han, Buxing,He, Jinling,Zhou, Xiaosi
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experimental part
p. 798 - 803
(2010/04/23)
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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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- Total synthesis of (-)-heptemerone B and (-)-guanacastepene E
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A concise, stereoselective, and convergent total synthesis of the unnatural enantiomer of the neodolastane diterpenoid heptemerone B has been completed. Saponification of (-)-heptemerone afforded (-)-guanacastepene E. The absolute stereochemistry of (-)-heptemerone B was thus established as 5-(S), the same as (-)-guanacastepene E. The longest linear sequence of the synthesis comprises 17 (18) steps from simple known starting materials. Our general synthetic approach integrates a diverse set of reactions, including an intramolecular Heck reaction to create one quaternary stereocenter and a cuprate conjugate addition for the establishment of the other. The central seven-membered ring was closed with an uncommon electrochemical oxidation, whereas the five-membered ring was formed through ring-closing metathesis. The absolute configuration of the two key building blocks was established through an asymmetric reduction and an asymmetric ene reaction.
- Miller, Aubry K.,Hughes, Chambers C.,Kennedy-Smith, Joshua J.,Gradl, Stefan N.,Trauner, Dirk
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p. 17057 - 17062
(2007/10/03)
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- Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
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The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica-supported PAMAM-Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.
- Zweni, Pumza P.,Alper, Howard
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p. 725 - 731
(2007/10/03)
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- Dilithiated phosphazenes: Scaffolds for the synthesis of olefins through a new class of bicyclic 1,2-oxaphosphetanes
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The first examples of the PN-directed dilithiation of (N-methoxycarbonyl)phosphazenes in the Cα and Cortho to the phosphorus, and the use of these dianions in the formation of tri- and tetra-substituted olefins through stereospecific thermolysis of a new type of isolable bicyclic 1,2-oxaphosphetanes are described.
- Garcia-Lopez, Jesus,Peralta-Perez, Emma,Forcen-Acebal, Angela,Garcia-Granda, Santiago,Lopez-Ortiz, Fernando
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p. 856 - 857
(2007/10/03)
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- Control of regioselectivity by the lone substituent through steric and electronic effects in the nitrosoarene ene reaction of deuterium-labeled trisubstituted alkenes
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For the ene reaction of 4-nitronitrosobenzene (ARNO) with a variety of primary and secondary lone alkyl-substituted substrates, the twix/twin regioselectivity is constant at about 85:15. In contrast, for the lone tert-butyl group and for lone aryl substituents, the twix regioisomer is obtained exclusively. These regioselectivities have been rationalized in terms of steric interactions and coordination between the enophile and the substrates in the transition states of the first reaction step.
- Adam, Waldemar,Krebs, Oliver,Orfanopoulos, Michael,Stratakis, Manolis
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p. 8395 - 8399
(2007/10/03)
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- Reactions of aliphatic ketones R2CO (R = Me, Et, iPr, and tBu) with the MCl4/Li(Hg) system (M = U or Ti): Mechanistic analogies between the McMurry, Wittig, and Clemmensen reactions
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Analysis of the products of the reactions of ketones R2CO (R = Me, Et, iPr, tBu) with the MCl4/Li(Hg) system (M = U, Ti) at 20°C revealed significant differences. For R = Me, the reaction proceeded exclusively (M = U) or preferentially (M = Ti) via a metallopinacol intermediate resulting from dimerization of ketyl radicals. Pinacol was liberated by hydrolysis, and tetramethylethylene was obtained after further reduction at 65°C. For R = iPr, formation of iPr2C=CiPr2 as the only coupling product, the nonproduction of this alkene by reduction of the uranium pinacolate [U]-OCR2CR2O-[U] (R = iPr) at 20°C, and the instability of the corresponding titanium pinacolate towards rupture of the pinacolic C-C bond indicated that reductive coupling of iPr2CO did not proceed by dimerization of ketyl radicals. Formation of 2,4-dimethyl-2-pentene was in favor of a carbenoid intermediate resulting from deoxygenative reduction of the ketyl. These results revealed that for sterically hindered ketones, McMurry reactions can be viewed as Wittig-like olefination reactions. For R = tBu, no coupling product was obtained and the alkane tBu2CH2 was the major product. The involvement of the carbenoid species [M]=CtBu2 was confirmed by its trapping with H2O, leading to tBu2CH2, and with the aldehydes RCHO, giving the cross-coupling products tBu2C=C(R)H (R = Me, tBu). Therefore, in the case of severely congested ketones, McMurry reactions present strong similarities to the Clemmensen reduction of ketones, owing to the involvement in both reactions of carbenoid species which exhibit similar reactivity. Wiley-VCH Verlag GmbH, 2001.
- Villiers, Claude,Ephritikhine, Michel
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p. 3043 - 3051
(2007/10/03)
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- Etudes des reactions d'oxydation du n-heptane et de l'isooctane
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The oxidation mechanisms of two alkanes that have quite different octane numbers: n-heptane (0) and isooctane (100), were investigated to obtain a better understanding of the chemical mechanism of autoignition phenomena and to improve the compatibility of the available fuels with the engines.The experimental study was performed at 923 K in a setup equipped with a jet-stirred reactor.The oxidation mechanisms of n-heptane and isooctane were simplified first by a purely kinetic analysis based on the product formation and then by using a software of simulation of reaction mechanisms.The very different behaviour of these two hydrocarbons was explained by the presence, in the products of isooctane oxidation, of alkenes, which would have an antiknock effect due to the formation of resonance-stabilized radicals. - Keywords: oxidation reaction; n-heptane; isooctane; autoignition; modelling
- Simon, Yves,Scacchi, Gerard,Baronnet, Francois
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p. 1391 - 1402
(2007/10/03)
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- REGIOSELECTIVE REPLACEMENT OF THE HYDROXY GROUP IN ALCOHOLS BY MEANS OF TRIHALOACETIC DERIVATIVES IN PRESENCE OF TRIPHENYLPHOSPHINE
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The investigation of the reactions of trichloroacetonitrile with 2-decanol, 2-methyl-3-octanol, 2,4-dimethyl-3-pentanol, and 2,2-dimethyl-1-propanol in presence of triphenylphosphine shows that the formation of alkyl chlorides from the corresponding alcohols goes regiospecifically: Even for 2,4-dimethyl-3-pentanol the amount of the isomeric chloride does not exceed 1percent, while neopentyl alcohol is converted into neopentyl chloride in 95percent yield.On the introduction of "external" nucleophiles (iodide and thiocyanate ions) into the reaction mixture the predominating reaction product is the alkyl chloride.As a result of the reaction of bromotrichloromethane with 1-nonanol and triphenylphosphine a mixture of the alkyl chloride and the alkyl bromide is formed.
- Matveeva, E. D.,Yalovskaya, A. I.,Cherepanov, I. A.,Bundel', Yu. G.,Kurts, A. L.
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p. 1409 - 1415
(2007/10/02)
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- Reduction of Alkyl Alkyl, Aryl Alkyl and Cyclic Ketones by Catalytic Hydrogen Transfer over Magnesium Oxide
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The reduction of a series of alkyl alkyl, aryl alkyl and cyclic ketones by catalytic hydrogen transfer (CTR) from isopropyl alcohol over magnesium oxide has been investigated.CTR over MgO was found to be an effective and selective route to the corresponding methanols.At temperatures above 523 K parasubstituted phenylmethanols underwent consecutive dehydration leading to the formation of the corresponding styrene derivative with satisfying yields.These processes were studied in a flow system working continuously.A long-time stability of the catalyst activity has been demonstrated.
- Kijenski, Jacek,Glinski, Marek,Czarnecki, Jacek
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p. 1695 - 1698
(2007/10/02)
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- Chemistry of Dicyclopropylcarbene and Related Intermediates in Dimethyl Sulfoxide
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The potassium salts of the anions of (phenylsulfonyl)hydrazones of diisopropyl, isopropyl cyclopropyl, and dicyclopropyl ketone were decomposed in dimethyl sulfoxide in the temperature range of 110-130 deg C.The diisopropyl phenylsulfonyl anion decomposes to form 2,4-dimethyl-2-pentene and diisopropyl ketone.Similar decomposition of the isopropyl cyclopropyl substrate forms 1-cyclopropyl-2-methylpropene, 1-isopropylcyclobutene, and isopropyl cyclopropyl ketone, while thermal decomposition of the dicyclopropyl ketone (phenylsulfonyl)-hydrazone anion forms cyclopropylcyclobutene and dicyclopropyl ketone.The rate constants for the first and second steps of the consecutive first-order decomposition of the (phenylsulfonyl)hydrazone anions were determined over the temperature range of 110-130 deg C.The activation parameters ΔH* (kcal/mol), ΔS* (eu), and ΔG* (kcal/mol) were calculated for the diazo compound to carbene step (k2) for the diisopropyl (15.6 +/- 1.1, -30.9 +/- 2.8, and 27.7 +/- 1.6), the isopropyl cyclopropyl (27.7 +/- 2.0, 3.3 +/- 5.1, and 26.4 +/- 2.8), and the dicyclopropyl (36.8 +/- 1.8, 28.4 +/- 4.6, 25.6 +/- 2.5).These results are discussed in terms of two factors: interaction of the cyclopropane ring with the functional group and orientation of the polar solvent.
- Freeman, Peter K.,Wuerch, Stephen E.,Clapp, Gary E.
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p. 2587 - 2590
(2007/10/02)
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- Homolytic Reactions of Ligated Boranes. Part 11. Electron Spin Resonance Studies of Radicals Derived from Primary Amine-Boranes
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Photochemically generated t-butoxyl radicals react with the primary amine-boranes RNH2->BH3 (R = Me or But) to form, initially, the nucleophilic amine-boryl radical RNH2->BH2, which subsequently abstracts hydrogen from the parent amine-borane to give the more stable isomeric aminyl-borane radical RNH->BH3.The amine-boryl radicals can be intercepted by alkyl bromides or chlorides or by nitriles, with which they react by halogen-atom abstraction or by addition to the CN group to give iminyl radicals, respectively.The e. s. r. spectra of the aminyl-borane radicals show the presence of extensive hyperconjugative delocalisation of the unpaired electron onto the BH3 group .Monoalkylaminyl-borane radicals react readily with alkenes, with arenes, and with conjugated or cumulated dienes to transfer a β-hydrogen atom from boron to give alkyl, cyclohexadienyl, or allyl radicals, respectively.Hydrogen atom transfer to alkenes from the electrophilic MeNH->BH3 takes place with high regioselectivity to give the more stable alkyl radical when two adducts are possible; the rate of transfer increases as the ionisation potential of the alkene decreases along the series CH2=CH2 BH3 to give the isopropyl radical was determined to be ca. 2 x 103 dm3 mol-1 s-1 at 282 K.Competition experiments have been carried out to determine the relative rates of the various reactions undergone by RNH2->BH2 and RNH->BH3.The results are interpreted with the aid of ab initio molecular-orbital calculations at the 6-31G level for RNH2->BH2, RNH->BH3, RNH2->BH3, and RNHBH2 (R = H or Me), together with similar calculations for the isoelectronic organic counterparts in which the NB moiety is replaced by a CC grouping.
- Kirwan, J. Nicolas,Roberts, Brian P.
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p. 539 - 550
(2007/10/02)
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- Use of the Diazoalkane-thione Reaction in the Synthesis of a Vinyltrimethylenemethane Precursor
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Previous studies have shown that the reaction of diazoalkanes with 3,5-dihydro-3,3,5,5-tetramethylpyrazole-4-thione (6) provide a flexible route for the synthesis of precursors to trimethylenemethane (TMM) (1) and tetramethylene-ethane (TME) (2) biradicals.We now show that this route can be adapted for the synthesis of a precursor to another type of non-Kekule polyene, a vinyl-TMM biradical (3).The thermal isomerisation of 1-(2,4-dimethylpent-1-en-3-ylidene)-2,2,3,3-tetramethylcyclopropane (27) to 4-isopropyl-3-isopropylidene-2,5-dimethylhexa-1,4-diene (11) which involves a vinyl-TMM intermediate (3-isopropyl-4-isopropylidene-2,5-dimethylhex-2-ene-1,5-diyl) was shown by deuterium labelling to involve a 1,6-hydrogen shift.It is suggested that such sigmatropic rearrangements of non-Kekule polyenes may involve orbital symmetry control.Related examples are discussed.Two reactions discovered incidentally in the course of this work are of some interest, one involving the synthesis of an allylic amine through the thermal rearrangement of an aziridine (2-isopropyl-3,3-aziridine) (16) and the other the formation of an oxathiole (20) through the reaction of a thione (6) and an α-diazo ketone (3-diazo-4-methylpentan-2-one) (18).
- Bushby, Richard,Mann, Stephen
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p. 2497 - 2504
(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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- Ring-opening of Alkyl-substituted Cyclopropanes in the Presence of Hydrogen on Copper
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In the presence of hydrogen on copper, the cyclopropanes (1), (2), and (3) are transformed into saturated hydrocarbons containing the same number of carbon atoms (alkenes are also formed, through isomerization of the cyclopropanes); these studies reveal the importance of a previously unknown property of copper in heterogeneous metal catalysis.
- Bartok, Mihaly,Palinko, Istvan,Molnar, Arpad
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p. 953 - 954
(2007/10/02)
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- Correlation of Alkyl and Polar Substituents at the Alcoholic Side of Tertiary Acetates with the Rate of Pyrolyses in the Gas Phase
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The rate coefficients for the gas-phase pyrolysis of several tertiary acetates have been measured in a static system over the temperature range of 220-340 deg C and pressure range of 40-186 torr.In seasoned vessels the reactions are homogeneous, follow a first-order rate law, and are unimolecular.The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for 3,3,3-trichloro-2-methyl-2-propyl acetate, log k1 (s-1) = (13.86 +/- 0.35) - (188.8 +/- 3.8) kJ mol-1 (2.303 RT)-1; for methyl α-acetoxyisobutyrate, log k1 (s-1) = (12.42 +/- 0.28) - (174.6 +/- 3.2) kJ mol-1 (2.303 RT)-1; for 2-methyl-2-hexyl acetate, log k1 (s-1) = (13.35 +/- 0.33) - (166.1 +/- 3.4) kJ mol-1 (2.303 RT)-1; for 2,4-dimethyl-2-pentyl acetate, log k1 (s-1) = (12.42 +/- 0.19) - (154.1 +/- 1.9) kJ mol-1 (2.303 RT)-1; for 2-methyl-2-acetoxy-4-phenylbutane, log k1 (s-1) = (11.97 +/- 0.55) - (151.5 +/-5.6) kJ mol-1 (2.303 RT)-1.The effectof substituents in the gas-phase elimination of 2-substituted 2-propyl acetates may be either electronic or steric in nature.The linear correlations for electron-releasing groups and for electron-withdrawing groups are presented and discussed.The results of the present work together with those reported in the literature lead to the establishment of a possible generalization on the influence of substituents at the alcohols side of primary, secondary, and tertiary acetates pyrolyses in the gas phase.
- Gonzalez, Neil,Martin, Ignacio,Chuchani, Gabriel
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p. 1314 - 1318
(2007/10/02)
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- Functionalization of terminal trisubstituted alkenes and derivatives thereof
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The invention relates to a process for preparing compounds having the general structure: STR1 wherein R is hydrogen or an acyclic or alicyclic fragment containing between one and about ten carbon atoms, and R1 is hydrogen or an alkyl containing between one and about four carbon atoms or an aryl group.
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- Electrophilic Cleavage of Cyclopropanes. Acetolysis of Alkylcyclopropanes
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The solvent kinetic hydrogen isotope effect showed that proton transfer is at least partially rate determining for the acetolysis of cyclopropanes which span a range of 1010 in reactivity.The energies and structures of protonated cyclobutanes were calculated and provide an explanation for the large difference in reactivity between cyclopropanes and cyclobutanes despite their similarity in enthalpies of reaction.The rates and products of acetolysis of a series of alkyl-substituted cyclopropanes were examined.The data, along with the results of ab initio calculations, indicate that for alkyl-substituted cyclopropanes, the protonated species is highly unsymmetrical.Cleavage of the cyclopropane ring always occurs so that the nucleophile becomes attached to the most substituted carbon, but the proton may attack either of the remaining carbons.Proton attack may lead to either retention or inversion of configuration depending on the orientation of the attacking proton with respect to the ring.
- Wiberg, Kenneth B.,Kass, Steven R.
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p. 988 - 995
(2007/10/02)
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- THE ALLYLIC REARRANGEMENT OF HYDROPEROXIDES : THE ALLYLPEROXYL RADICAL
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The free-radical rearrangement of pinocarveyl hydroperoxide (1) or myrtenyl hydroperoxide (2) in hexane produces an equilibrium mixture of both hydroperoxides.The absence of carbon skeletal rearrangement suggests that the intermediate radical involved in hydroperoxide isomerization has its unpaired electron localized elsewhere than the α-carbon atom.The failure of oxygen to react with pinocarveyl, myrtenyl, and acyclic hydroperoxides (8) and (9) during the allylic rearrangement supports this suggestion.The kinetics of the rearrangement of 1-isopropyl-2-methylallyl hydroperoxide (8) is compatible with a mechanism in wich the intermediate is a common allylperoxyl radical produced directly from either allylic isomer.
- Brill, William F.
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p. 621 - 628
(2007/10/02)
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- Photochemistry of Alkyl Halides. 10. Vinyl Halides and Vinylidene Dihalides
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The photobehavior of the acyclic vinyl iodide 2, the 1-iodocycloalkenes 11-14 and 39, the (halomethylene)cycloalkanes 45-48, and the (dihalomethylene)cyclohexanes 62-64 has been studied.Except for the dichloride 64, which exhibited only radical behavior, each of the halides afforded a mixture of ionic and radical products.The two bromides studied, 48 and 63, afforded lower ratios of ionic to radical products than the corresponding iodides 45 and 62.Irradiation of vinyl iodides was found to be a convenient and powerful method for the generation of vinyl cations, including the highly strained 1-cyclohexenyl and 1-cyclopentenyl cations and the unstabilized α-unsubstituted cations 51 and 54.The latter cations underwent rearrangement to the ring-expanded 1-cycloalkenyl cations 28 and 36, respectively.Lowering the temperature of the irradiation of iodides 13, 14, and 45 resulted in an increased ratio of ionic to radical products.However, iodide 47, which underwent principally fragmentation to enyne 61, showed little temperature effect.
- Kropp, Paul J.,McNeely, Steven A.,Davis, Robert Drummond
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p. 6907 - 6915
(2007/10/02)
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- REARRANGEMENT OF CYCLOPROPYL, SUBSTITUTED VINYL AND ALKYL GROUPS TO DIVALENT CARBON.
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The relative carbenic migratory abilities of cyclopropyl, β,β-dimethylvinyl, methyl,ethyl and isopropyl groups have been determined.
- Kraska, A. R.,Cherney, L. I.,Shechter, H.
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p. 2163 - 2166
(2007/10/02)
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- Regioselectivity of the Protolysis of (η3-Allyl)bis(η5-cyclopentadienyl)titanium Complexes with Hydrogen Chloride
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Reaction of the (η3-allyl)bis(cyclopentadienyl)titanium compounds 1, 2 and 5, in which the allyl group is alkyl substituted in position 1 or 1 and 2, with hydrogen chloride has an opposite regioselectivity in ether to that in tetrahydrofuran.In ether, attack by the proton occurs preferentially on the unsubstituted C-3 while in tetrahydrofuran the preferred position for attack is C-1.
- Lehmkuhl, Herbert,Fustero, Santos
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p. 1371 - 1375
(2007/10/02)
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- Lactone production
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Gamma-butyrolactones are prepared by the reaction of carbon monoxide with a 3-alkene-1-ol in the presence of a platinum group metal compound.
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