689-97-4Relevant academic research and scientific papers
An investigation of hydrogen bonding between HCl and vinylacetylene: A molecule with two different ?-acceptor sites
Kisiel, Z.,Fowler, P. W.,Legon, A. C.,Devanne, D.,Dixneuf, P.
, p. 6249 - 6255 (1990)
The ground state rotational spectrum of a hydrogen-bonded dimer formed by vinylacetylene and hydrogen chloride has been detected by the pulsed-nozzle, Fourier-transform microwave technique.Vinylacetylene has been chosen as a prototype acceptor molecule containing two different ?-acceptor sites.Rotational constants A0, B0, C0, centrifugal distortion constants ΔJ, ΔJK, δJ, δJK, and three components χaa, χbb - χcc, and χab of the Cl nuclear quadrupole coupling tensor have been determined for each of the three isotopomers CH2CHCCH...HCl, CH2CHCCH...HCl, and CH2CHCCH...D35Cl.These spectroscopic constants have been interpreted in terms of a dimer in which the HCl subunit forms a hydrogen to the CC triple bond in a T-shape configuration, but is displaced from the center of the triple bond by d = 0.04 Angstroem towards the inner C atom, and makes an angle φ = 34 deg with the vinylacetylene plane.The experimental angular geometry is in excellent agreement with that predicted by the Buckingham-Fowler electrostatic model which gives φ = 27 deg.
The i.r., Raman and microwave spectra of 1-butene-3-yne (vinylacetylene) and 1-butene-3-yne-4d
Torneng, E.,Nielsen, C. J.,Klaeboe, P.,Hopf, H.,Priebe, H.
, p. 975 - 988 (1980)
The i.r. spectra of 1-butene-3-yne and 1-butene-3-yne-4d in the vapour phase and as crystalline solids at 90 K were recorded in the region 5000-100 cm-1.Raman spectra, including semiquantitative polarization data, of the neat liquid and of the solid were obtained at 90 K.Microwave spectra of the compounds were recorded in the region 8-40 GHz at ambient temperature.Rotational transitions of the vibrational ground state and of the two lowest vibrational excited states ν13(a') and ν18(a'') were measured.The fundamental frequencies of both compounds were assigned in excellent agreement with the results of normal coordinate calculations.Rotational fine structure was observed for several bands and interpreted as the Q-sub-branches of the perpendicular bands (in the symmetrical top approximation).For six bands the Q-sub-branches were assigned to the proper K-values.The Coriolis coupling constant ξa13,18 was derived from the i.r. and from the microwave spectra.
Reaction Mechanism of the Homogeneous Thermal Decomposition of Acetylene
Tanzawa, T.,Gardiner, W. C.
, p. 236 - 239 (1980)
A modeling study is reported in which experiments on the rate of and product distribution from C2H2 pyrolysis from 625 to 3400 K are described with a single mechanism.The essential primary mechanism at low temperatures proves to consist of an H-atom, vinyl radical chain H + C2H2 -> C2H3, C2H3 + C2H2 -> C4H4+ H producing vinyl acetylene at early times.At high temperatures this is replaced by the ethynyl chain H + C2H2 -> C2H + H2, C2H + C2H2 + H producing diacetylene.By considering a variety of studies simulteneusly it was possible to assign rate constant expressions to the key elementary reactions.While all of the basic observations on the primary decomposition are accounted for by final mechanism, uncertainties still remain in the rates of secondary reactions and in the magnitudes of the fallof corrections required for the unimolecular reactions involved.
Nitrogen-Modified Activated Carbon Supported Cu(II)Cu(I)/NAC Catalysts for Gas–Solid Acetylene Dimerization
Li, Congcong,Xie, Jianwei,Zhang, Jinli,Dai, Bin
, p. 2990 - 2995 (2021)
Improving dispersibility and stability of Cu(II)Cu(I)/activated carbon (AC) is a crucial aspect for enhancing its catalytic performance in the process of gas–solid acetylene dimerization. The Cu(II)Cu(I)/NAC-500 catalyst using nitrogen-modified AC (NAC) as a support, delivered excellent catalytic performance and stability vs undoped Cu(II)Cu(I)/AC at 100?°C and 120?h?1 of C2H2 gas hourly space velocity. Under the optimal conditions, the Cu(II)Cu(I)/NAC-500 catalyst exhibited a stable catalytic performance during a 10?h test with 65% C2H2 conversion; and the selectivity to monovinylacetylene (MVA) reached 86%. The existence of nitrogen species can increase the interaction between copper and the support, and increase dispersion of the copper species on the support, which were benefit for the catalytic performance. Graphic Abstract: [Figure not available: see fulltext.]
A novel risedronic acid-modified Nieuwland catalyst for acetylene dimerization
Zhang, Qixia,Li, Congcong,Luo, Juan,Xie, Jianwei,Zhang, Jinli,Dai, Bin
, (2020)
Nieuwland catalyst (NC) was modified with different phosphonic acids (Px) and evaluated for their acetylene dimerization activity in monovinyl acetylene (MVA) production. Nearly 49.2% of acetylene conversion and 80.3% of MVA selectivity were obtained in 5 mol% risedronic acid (P2)-modified NC under an acetylene-gas space velocity of 105 h?1 at 80 °C, which was 17.8% higher than the yield of the control NC. The characterization results of NC and P2–NC indicated that the addition of P2 effectively enhanced the stability of the Cu ions and inhibited oxidation of the active component Cu+, improving their catalytic activity and long-term stability.
Hydrazinylbenzenesulfonic Acid-Modified Nieuwland Catalyst for Acetylene Dimerization Reaction
Zhang, Qixia,Li, Congcong,Luo, Juan,Xie, Jianwei,Zhang, Jinli,Dai, Bin
, p. 1766 - 1773 (2020)
Abstract: A novel Nieuwland catalytic system, containing 5?mol% of 4-hydrazinylbenzenesulfonic acid (S8), was developed and exhibited an excellent catalytic performance and good stability in the acetylene dimerization reaction. The acetylene conversion reached 57.1%, while the selectivity of monovinylacetylene (MVA) was 75.1%. The yield of MVA was maintained at 42.9% under an acetylene gas hourly space velocity (GHSV) of 80?h?1 at 80?°C, which was increased by 18.8% over the control Nieuwland catalytic system. The addition of S8 increased the dissolution of CuCl in water, inhibited the polymer formation, and hindered the Cu+ loss during the reaction process, thus improving the activity and the long-term stability of the modified Nieuwland catalyst. Graphic Abstract: [Figure not available: see fulltext.]
Kinetics of copper(I)-catalyzed dimerization and hydration of acetylene in water
Tokita, Yuichi,Okamoto, Akio,Nishiwaki, Kenichiro,Kobayashi, Mineto,Nakamura, Eiichi
, p. 1395 - 1399 (2004)
The kinetics of the dimerization and hydration of acetylene in water with a copper(I) catalyst, a so-called Nieuwland catalyst, were investigated. The stationary state kinetics for both reactions could be described assuming that the rate-controlling step is a second-order reaction of an activated catalyst, [H-Cl-Cu-C2H], formed in the reaction mixture, with acetylene or water. The activation energies and activation entropies were 12.4 kcal·mol-1 and -33.3 cal·mol-1·K -1 for the acetylene dimerization, and 17.5 kcal·mol -1 and -34.2 cal·mol-1·K-1 for the acetylene hydration, respectively. The large negative values of activation entropy for these reactions may be accounted for by the role of water as a kind of cocatalyst.
Gas-solid acetylene dimerization over copper-based catalysts
Li, Congcong,Luo, Juan,Zhang, Qixia,Xie, Jianwei,Zhang, Jinli,Dai, Bin
, p. 13608 - 13615 (2019)
Acetylene dimerization is an important step in an acetylene-based process for chloroprene production, and the traditional catalyst for this transformation is the Nieuwland catalyst in a bubble column reactor. However, the drawbacks of this catalyst are the use of high concentration of a copper reagent, low acetylene conversion and monovinylacetylene (MVA) selectivity, and the difficulty to generate or reuse the catalytic system. Therefore, in this study, we first reported a gas-solid acetylene dimerization reaction by applying copper-supported catalysts, which were prepared via an impregnation technique using CuCl as the precursor. The catalytic activity was examined and discussed in detail by modification of the impregnation solvent, Cu loading amount, reaction temperature, and the acetylene gas hourly space velocity. Under optimal conditions, the catalyst exhibited a maximum acetylene conversion of 48.3% and a monovinylacetylene selectivity of 87.4%. The catalysts were characterized by TGA, XRD, H2-TPR, TEM, BET, XPS and ICP-AES. Not only the preparation, isolation and recycling of the supported catalyst were easy in the gas-solid reaction, but also the supported catalyst overcame the shortcomings of the liquid phase catalyst. The loss of the Cu active species is concluded to be the main factor causing the decrease in the catalytic activity.
HETEROGENIZED CATALYST FOR ACETYLENE DIMERIZATION
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Paragraph 0034-0037; 0039, (2018/04/12)
A catalyst and a process for using the catalyst are presented. The catalyst is a heterogeneous catalyst and includes active metal halides bonded to functional groups. The functional groups are bonded to a polymeric backbone to form the structure supporting the catalyst. The catalyst is useful for the dimerization of acetylene to convert the acetylene to a larger hydrocarbon, and in particular to dimerize acetylene to vinylacetylene.
Formation of fulvene in the reaction of C2H with 1,3-butadiene
Lockyear, Jessica F.,Fournier, Martin,Sims, Ian R.,Guillemin, Jean-Claude,Taatjes, Craig A.,Osborn, David L.,Leone, Stephen R.
, p. 232 - 245 (2015/04/14)
Abstract Products formed in the reaction of C2H radicals with 1,3-butadiene at 4 Torr and 298 K are probed using photoionization time-of-flight mass spectrometry. The reaction takes place in a slow-flow reactor, and products are ionized by tunable vacuum-ultraviolet light from the Advanced Light Source. The principal reaction channel involves addition of the radical to one of the unsaturated sites of 1,3-butadiene, followed by H-loss to give isomers of C6H6. The photoionization spectrum of the C6H6 product indicates that fulvene is formed with a branching fraction of (57 ± 30)%. At least one more isomer is formed, which is likely to be one or more of 3,4-dimethylenecyclobut-1-ene, 3-methylene-1-penten-4-yne or 3-methyl-1,2-pentadien-4-yne. An experimental photoionization spectrum of 3,4-dimethylenecyclobut-1-ene and simulated photoionization spectra of 3-methylene-1-penten-4-yne and 3-methyl-1,2-pentadien-4-yne are used to fit the measured data and obtain maximum branching fractions of 74%, 24% and 31%, respectively, for these isomers. An upper limit of 45% is placed on the branching fraction for the sum of benzene and 1,3-hexadien-5-yne. The reactive potential energy surface is also investigated computationally. Minima and first-order saddle-points on several possible reaction pathways to fulvene + H and 3,4-dimethylenecyclobut-1-ene + H products are calculated.
