2004-69-5Relevant articles and documents
Tetravinylallene
Elgindy, Cecile,Ward, Jas S.,Sherburn, Michael S.
supporting information, p. 14573 - 14577 (2019/09/13)
The first chemical synthesis of tetravinylallene (3,5-divinylhepta-1,3,4,6-tetraene) is reported. The final, key step of the synthesis involves a palladium-catalyzed, Negishi-type cross-coupling involving 1,5-transposition of a penta-2-en-4-yn-1-ol methanesulfonate. The unprecedented fundamental hydrocarbon is sufficiently stable to be purified by flash chromatography. A similar synthetic pathway grants access to the first substituted tetravinylallenes, which provide insights into the influence of substitution upon stability and reactivity. Tetravinylallenes are shown to break new ground in swift structural complexity creation, with three novel sequences reported.
Study of Methylidyne Radical (CH and CD) Reaction with 2,5-Dimethylfuran Using Multiplexed Synchrotron Photoionization Mass Spectrometry
Carrasco, Erica,Meloni, Giovanni
, p. 6118 - 6133 (2018/07/09)
At 298 K the reactions of 2,5-dimethlyfuran + CH(X2Θ) and + CD radicals were investigated using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Laboratory. Reaction products wer
Reaction rate and isomer-specific product branching ratios of C 2H + C4H8: 1-butene, cis -2-butene, trans -2-butene, and isobutene at 79 K
Bouwman, Jordy,Fournier, Martin,Sims, Ian R.,Leone, Stephen R.,Wilson, Kevin R.
, p. 5093 - 5105 (2013/07/25)
The reactions of C2H radicals with C4H8 isomers 1-butene, cis-2-butene, trans-2-butene, and isobutene are studied by laser photolysis-vacuum ultraviolet mass spectrometry in a Laval nozzle expansion at 79 K. Bimolecular-reaction rate constants are obtained by measuring the formation rate of the reaction product species as a function of the reactant density under pseudo-first-order conditions. The rate constants are (1.9 ± 0.5) × 10-10, (1.7 ± 0.5) × 10 -10, (2.1 ± 0.7) × 10-10, and (1.8 ± 0.9) × 10-10 cm3 s-1 for the reaction of C2H with 1-butene, cis-2-butene, trans-2-butene, and isobutene, respectively. Bimolecular rate constants for 1-butene and isobutene compare well to values measured previously at 103 K using C2H chemiluminescence. Photoionization spectra of the reaction products are measured and fitted to ionization spectra of the contributing isomers. In conjunction with absolute-ionization cross sections, these fits provide isomer-resolved product branching fractions. The reaction between C2H and 1-butene yields (65 ± 10)% C4H4 in the form of vinylacetylene and (35 ± 10)% C5H6 in the form of 4-penten-1-yne. The cis-2-butene and trans-2-butene reactions yield solely 3-penten-1-yne, and no discrimination is made between cis- and trans-3-penten-1-yne. Last, the isobutene reaction yields (26 ± 15)% 3-penten-1-yne, (35 ± 15)% 2-methyl-1-buten-3-yne, and (39 ± 15)% 4-methyl-3-penten-1-yne. The branching fractions reported for the C2H and butene reactions indicate that these reactions preferentially proceed via CH3 or C2H3 elimination rather than H-atom elimination. Within the experimental uncertainties, no evidence is found for the formation of cyclic species.
Bimolecular rate constant and product branching ratio measurements for the reaction of C2H with ethene and propene at 79 K
Bouwman, Jordy,Goulay, Fabien,Leone, Stephen R.,Wilson, Kevin R.
experimental part, p. 3907 - 3917 (2012/07/02)
The reactions of the ethynyl radical (C2H) with ethene (C 2H4) and propene (C3H6) are studied under low temperature conditions (79 K) in a pulsed Laval nozzle apparatus. Ethynyl radicals are formed by 193 nm photolysis of acetylene (C 2H2) and the reactions are studied in nitrogen as a carrier gas. Reaction products are sampled and subsequently photoionized by the tunable vacuum ultraviolet radiation of the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The product ions are detected mass selectively and time-resolved by a quadrupole mass spectrometer. Bimolecular rate coefficients are determined under pseudo-first-order conditions, yielding values in good agreement with previous measurements. Photoionization spectra are measured by scanning the ALS photon energy while detecting the ionized reaction products. Analysis of the photoionization spectra yields-for the first time-low temperature isomer resolved product branching ratios. The reaction between C2H and ethene is found to proceed by H-loss and yields 100% vinylacetylene. The reaction between C2H and propene results in (85 ± 10)% C4H4 (m/z = 52) via CH3-loss and (15 ± 10)% C5H6 (m/z = 66) by H-loss. The C 4H4 channel is found to consist of 100% vinylacetylene. For the C5H6 channel, analysis of the photoionization spectrum reveals that (62 ± 16)% is in the form of 4-penten-1-yne, (27 ± 8)% is in the form of cis-and trans-3-penten-1-yne and (11 ± 10)% is in the form of 2-methyl-1-buten-3-yne.
UV laser photodeposition of nanomagnetic soot from gaseous benzene and acetonitrile-benzene mixture
Pola, Josef,Ouchi, Akihiko,Mary?ko,Vorlí?ek,?ubrt, Jan,Bakardjieva,Bastl, Zdeněk
experimental part, p. 188 - 194 (2012/02/02)
Megawatt KrF laser gas-phase photolysis of benzene and acetonitrile-benzene mixture was studied by using mass spectroscopy-gas-chromatography and Fourier transform infrared spectroscopy for analyses of volatile products, and by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, electron microscopy and magnetization measurements for analyses of solid products deposited from the gas-phase. The results are consistent with carbonization of benzene and decomposition of non-absorbing acetonitrile in carbonizing benzene through collisions with excited benzene and/or its fragments. The solid products from benzene and acetonitrile-benzene mixture have large surface area and are characterized as nanomagnetic amorphous carbonaceous soot containing unsaturated C centers prone to oxidation. The nanosoot from acetonitrile-benzene mixture incorporates CN groups, confirms reactions of benzene fragments with CN radical and has a potential for modification by reactions at the CN bonds.
An efficient and stereoselective synthesis of xerulin via Pd-catalyzed cross coupling and lactonization featuring (E)-lodobromoethylene as a novel two-carbon synthon.
Negishi,Alimardanov,Xu
, p. 65 - 67 (2007/10/03)
[structure: see text] Xerulin, an inhibitor of cholesterol biosynthesis, has been synthesized from commercially available (E)-1-bromopropene, acetylene, and propynoic acid in five steps (longest linear sequence) in 30% overall yield and >96% stereoselectivity. The preparation of (E)-iodobromoethylene and its use in the Pd-catalyzed cross coupling are two of the novel aspects of the synthesis reported herein.
Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 1. Preparation of Aliphatic and Therminal Alkynes
Aitken, R. Alan,Atherton, J. Ian
, p. 1281 - 1284 (2007/10/02)
Thermal extrusion of Ph3PO from β-oxoalkylidenetriphenylphosphoranes 4 to give the alkynes 5, which under conventional pyrolysis conditions is restricted to cases in which R1 is an electron withdrawing group, has been successfully achieved for R1=H or alkyl by using FVP.The method allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and acid chlorides 3 in three steps with good overall yields.Under the conditions used the ylides with R2 = cyclobutyl also undergo less of ethene to provide convenient access to the vinylalkynes 6.
Butyllithium-induced dimerization of pent-3-en-1-yne and related additions
Klusener, P. A. A.,Hommes, H.,Hanekamp, J. C.,Kerk, A. C. H. T. M. van der,Brandsma, L.
, p. 67 - 81 (2007/10/02)
The enynes HCCCH=CHCH2R (R = H, Me, OMe, NMe2, SMe), are converted into dimers by treatment with slightly more than two equivalents of butyllithium.The Z-configuration predominates in the dimers obtained after aqueous work-up.The lithiated enynes (R = H, Me, SMe) and acetylenic compounds LiCCCH2R (R = SMe, C6H5) add in an analogous way to the double bond of LiCCCH=CH2.
Thermal Rearrangements, XVIII. - Gas Phase Pyrolysis of Cyclopropylacetylene
Hopf, Henning,Wachholz, Gerhard
, p. 1259 - 1262 (2007/10/02)
The gas phase pyrolysis of cyclopropylacetylene (3) has been investigated in a flow system between 600 and 900 deg C.At the lower temperature limit 3 isomerizes to give 1,2,4-pentatriene (9), cis- (10) and trans-3-penten-1-yne (11), as well as 1-penten-4-yne (12), all isomers being formed in roughly equal amounts.At 850 deg C none of these C5H6-hydrocarbons is formed; rather, 1,3-cyclopentadiene (13), benzene (14), toluene (15), indene (16), naphthalene (17), and acenaphthylene (18) are the major constituents of a complex pyrolysate.The mechanisms of formation of the major pyrolysis products are discussed.
A New General Synthesis of Aliphatic and Terminal Alkynes: Flash Vacuum Pyrolysis of β-Oxoalkylidenetriphenylphosphoranes
Aitken, R. Alan,Atherton, J. Ian
, p. 1140 - 1141 (2007/10/02)
By using flash vacuum conditions the thermal elimination of Ph3PO from β-oxoalkylidenetriphenylphosphoranes, previously confined to cases with an α-electron withdrawing group, has been extended to provide a general, high yielding synthesis of aliphatic and terminal alkynes.
