27987-87-7Relevant academic research and scientific papers
Kinetics of the reactions of hydroxyl radicals with diacetylene and vinylacetylene
Sommerer, J?rg,Olzmann, Matthias
, p. 495 - 505 (2015)
Highly unsaturated hydrocarbons like diacetylene (C4H2) or vinylacetylene (C4H4) are important intermediates in combustion that can have impact on soot formation. One of their major loss channels is reaction with hydroxyl radicals (OH). We studied the reactions C4H2 + OH → products (1) and C4H4 + OH → products (2) in a quasi-static reactor with helium as bath gas. The hydroxyl radicals were produced by laser flash-photolysis of nitric acid at a wavelength of 248 nm and detected by laser-induced fluorescence with excitation at 282 nm. The rate coefficients were obtained from the intensity-time profiles under pseudo-first order conditions with respect to OH. We found a virtually temperature-independent rate coefficient for reaction (1): k1 = (1.0 ± 0.3) × 10-11 cm3 s-1 (T = 290-670 K, P = 2.7-30.5 bar) and a weakly negative temperature-dependent rate coefficient for reaction (2): k2(T) = (6.4 ± 1.9) × 10-12 exp (486 K/T) cm3 s-1 (T = 295-740 K, P = 1.7-19.2 bar). For neither of the two reactions pressure dependence was observed. From comparisons with analogous reaction systems, we conclude that the dominating reaction pathway is OH addition, where in the case of C4H4 the double bond is preferred over the triple bond.
KINETICS AND MECHANISM OF HYDROCARBON FORMATION IN THE SYSTEM C2H2/O/H AT TEMPERATURES UP TO 1300 K.
Homann,Wellmann
, p. 609 - 616 (1983)
The consumption of O atoms and the formation of CO, C//3H//4 (Propyne and propadiene), C//4H//2 (Butadiyne) and other hydrocarbons in the system C//2H//2/O with and without added H atoms has been studied in the temperature range 295-1300 K, p equals 2. 7 mbar. Both the rate of formation and the yield of C//3H//4 in C//2H//2-rich mixtures increases with higher temperature. The rate of C//4H//2 formation increases but the maximum concentration remains constant up to 500 K. The results can be described quantitatively through a slightly modified mechanism of 30 reactions that had been proposed previously for the reaction at room temperature.
Temperature Dependence of the Rate Constants for the Reactions of C2H with C2H2, H2, and D2
Koshi, Mitsuo,Fukuda, Koichi,Kamiya, Kenshu,Matsui, Hiroyuki
, p. 9839 - 9843 (1992)
Reactions of ethynyl (C2H) radical with C2H2, H2, and D2 were studied over the temperature range 298-438 K by time-resolved mass spectrometry.The rate of the reaction with C2H2 was followed by measuring the appearance rate of C4H2.The rates of the reactions with H2 and D2 were deduced by measuring the dependence of C4H2 production (arising from the reaction C2H with the C2H2 precursor) on the partial pressure of added H2 or D2.The rate constants for the reaction C2H + C2H2 -> C4H2 + H were also measured following reflected shock waves by monitoring H atom resonant absorption at 121.6 nm.In both experiments, the C2H radical was generated by ArF (193-nm) laser photolysis of C2H2.A rate constant of (1.5 +/- 0.3) * 10-10 cm3 molecule-1 s-1 was obtained for reaction 1 without any temperature dependence at T = 298-2177 K.The results for the reactions C2H + H2 -> C2H2 + H and C2H + D2 -> C2HD + D could be represented by the Arrhenius expressions, k2 = (1.8 +/- 1.0) * 10-11 exp(-(1090+/-299)/T) and k3 = (1.4+/-0.8) * 10-11 exp(-(1377+/-301)/T) cm3 molecule-1 s-1, over the range of T = 298-438 K.The classical barrier height for reactions 2 and 3 was estimated to be 2 kcal/mol on the basis of conventional transition-state theory.The isotope effects on reactions 2 and 3 calculated with Wigner tunneling correction were in good agreement with the present results.
Absolute IR Band Intensities of Diacetylene in the 250-4300 cm-1 Region: Implications for Titan's Atmosphere
Khlifi, M.,Paillous, P.,Delpech. C.,Nishio, M.,Bruston, P.,Raulin, F.
, p. 116 - 122 (1995)
The infrared spectrum of C4H2, butadyine (also called diacetylene), has been experimentally investigated in the region from 250 to 4300 cm-1 using a Fourier transform spectrometer.A total of 12 bands have been analyzed.For each band, the characteristic wavenumber has been deduced and the values of the absolute band intensities have been systematically determined together with their associated uncertainties.The results provide important data for planetary studies.In particular, a better estimate of the mean statospheric abundance of butadiyne in Titan's atmosphere is obtained: its value is about 50percent higher than previously reported.
Photochemistry of Acetylene at 193.3 nm
Seki, Kanekazu,Okabe, Hideo
, p. 5284 - 5290 (1993)
The quantum yield (QY) of diacetylene in the 193.3 nm photolysis of acetylene has been measured as a function of pressure, decomposition, and added gases.The QY of diacetylene is near unity (0.9 +/-0.1) when the decomposition is 1percent or less.The QY of C2H2 + hν -> C2H + H is 0.3 +/- 0.1, which is determined by the C2HD yield from the photolysis of C2H2 + C2D6 (or D2) mixtures.The yields is in good agreement with the QY of H atoms photodissociated from C2H2; C2H reacts with C2H2 to produce an equivalent amount of diacetylene.The remaining 60-70percent diacetylene arises from the metastable acetylen (C2H2**) reacting with ground-state acetylene at 193.3 nm and above 0.1 Torr of acetylene.The quenching of diacetylene formed via C2H2** by various foreign gases at various wavelengths is compared.The quenching order at 193.3 nm is N2 D2 H2 C2D6 n-C4H10.It is postulated that an adduct from C2H2** + C2H2 is initially formed before it dissociates into C2H4 + H2 or C2H + C2H3.Yields of C4H2, C2HD, and C2H2 were measured by FT-IR calibrated with pure samples.The C4H2 yield at 193 nm does not change with addition of N2 up to 600 Torr.The absorption cross section of C2H2 has been measured in the 190 - 230-nm region.The production of C4H2 was examined at wavelength below and above the dissociation threshold.The metastable acetylene reactions may be important in haze formation in Titan's atmosphere.
Photochemistry of acetylene at 1470 Angstroem
Okabe, Hideo
, p. 2772 - 2778 (1981)
The photolysis of acetylene at 1470 Angstroem has been studied over the pressure region from 13 to 1330 Nm-2 (0.1 to 10 Torr).The quantum yield of diacetylene formation has been measured as a function of C2H2 pressure and the partial pressures of He and H2.The quantum yields of acetylene disappearance and of ethylene and hydrogen formation were also briefly studied.From these results it was concluded that the major primary photochemical process is direct dissociation C2H2 -> C2H + H with a quantum yield of 0.3 and the process of H2 production C2H2 -> C2 + H2 is minor (quantum yield 0.1).The remaining process is the formation of a metastable acetylene which reacts either with ground state acetylene to form C2H radicals or is deactivated by collisions with the walls or inert gases.The C2H radicals react with H2 130 +/- 11 times slower and with CH4 31 +/- 1.7 times slower than with C2H2.Absorption cross sections of diacetylene have been measured in the 1200 and 1800 Angstroem region.The role of acetylene photolysis in the Jovian atmosphere is briefly discussed.
A detailed procedure for the preparation of butadiyne
Verkruijsse,Brandsma
, p. 657 - 659 (1991)
Butadiyne, HC ≡ CC ≡ CH, can be obtained in yields up to ~90% by adding 1,4-dichloro-2-butyne, ClCH2C ≡ CCH2Cl at ~70°C to a mixture of concentrated aqueous potassium hydroxide and dimethylsulfoxide.
Submerged electric arc between graphite electrodes: A one-pot tool for the synthesis of long-chain polyynes in solution
Cataldo, Franco
, p. 141 - 144 (2004)
Polyynes, a class of molecules described by the general formula H-(CC) mH (where m is an integer) can be synthesized using an electric arc between graphite electrodes submerged in an organic solvent such as methanol, n-hexane, n-dodecane, decahydronaphthalene or acetonitrile. When the electric arc is used in acetonitrile at -40°C, polyyne chains of up to 18 carbon atoms (m=9) have been produced together with monocyanopolyyne as by-product. The polyynes can be reduced to ene-ynes by shaking a hexane solution of them with Zn/HCl.
SYMMETRISCH SUBSTITUIERTE BUTADIINKOMPLEXE VON WOLFRAM(IV)
Stahl, Karlheinz,Dehnicke, Kurt
, p. 85 - 94 (1986)
The butadiyne complexes x and x are synthesized by the reaction of tungsten hexachloride with Me3SiC*CC*CSiMe3 and IC*CC*CI, respectively, in boiling CCl4.The complexes are associated by chloro bridges WCl2W.They react with pyridine or diethyl ether to form the adducts (X = SiMe3, I; Y = pyridine, diethyl ether).The thermally and mechanically very stable diiodobutadiyne complex reacts with (PPh3CH2I)Cl forming the chloro complex (PPhCH2I)2 which is very soluble in dichloromethane.This chloro complex reacts with silver chloride to form the dichlorobutadiyne complex (PPh3CH2I)2 which is also very stable.The results of IR and 13C NMR spectra correspond to the carbon-carbon triple bonds acting as four-electron donors, and the bonding to tungsten is best described as being of the metallacyclopropene type.
A Flow Tube Study of Ion-Molecule Reactions of Acetylene
Knight, J. S.,Freeman, C. G.,McEwan, M. J.,Anicich, V. G.,Huntress, W. T.
, p. 3898 - 3902 (1987)
The reactivities of C2Hy+, C4Hy+, and C6Hy+ (0 y+ cations into C6- and C8-based cyclic hydrocarbons.Significant differences were noted in reaction rate and product ion distribution between low-pressure and high-pressure techniques of investigating association reactions.Isomeric structures of C4H4+, C6H4+, and C6H5+ are distinguished.
