2669-89-8Relevant academic research and scientific papers
The vinyl radical investigated by infrared diode laser kinetic spectroscopy
Kanamori, Hideto,Endo, Yasuki,Hirota, Eizi
, p. 197 - 205 (1990)
A c-type band was observed at around 895 cm-1 by infrared diode laser kinetic spectroscopy combined with the excimer laser photolysis of vinyl halides at 193 nm and was assigned to the CH2 wagging mode of the vinyl radical.The band was found to consist of two component bands separated by 0.0541(11) cm-1.Both component bands showed clearly the statistical weight in an alternative way, that is, of one shows the weight 1:3 for even:odd Ka levels, the other exhibits 3:1, indicating that the radical is of C2υ effective symmetry, executing a double-minimum motion probably associated with the C-H in-plane rocking vibration.The upper states of the two bands were found to be perturbed weakly, possibly by a Coriolis interaction with the first overtone state of the C-H rocking mode.
Competitive hydrogen-atom abstraction versus oxygen-atom and electron transfers in gas-phase reactions of [X4O10]+ (X = P, V) with C2H4
Dietl, Nicolas,Engeser, Marianne,Schwarz, Helmut
, p. 4452 - 4456 (2010)
(Figure Presented) Why so different? The comparison of the reaction of "bare" [P4O10],+ and [V4O 10]"+with ethene by mass-spectrometric and computational studies permits insight into mechanistic aspects of the c
193 nm photolysis of vinyl bromide: Nascent product distribution of the C2H3Br→C2H2 (vinylidene)+HBr channel
Liu,Letendre,Dai
, p. 1734 - 1741 (2007/10/03)
The internal energy content of fragment HBr and C2H2 following photolysis of the precursor, vinyl bromide, at 193 nm was determined using time-resolved Fourier transform spectroscopy (TR FTS). Data taken 1 μs after the laser photolys
Site-specific dissociation dynamics of ethylene at 157 nm: atomic and molecular hydrogen elimination
Lin, Jim J.,Wang, Chia C.,Lee, Yuan T.,Yang, Xueming
, p. 9668 - 9677 (2007/10/03)
Photodissociation of five ethylene isotopomers at 157 nm was studied using a molecular beam apparatus. From this study, complete and interesting information on the site and isotope effects on the molecular hydrogen elimination processes from ethylene were also detected. Using the new improved experimental technique, dynamical differences between different microchannels of molecular hydrogen elimination processes from ethylene were also detected. Site and isotopic effects on the molecular hydrogen elimination processes were also clearly observed.
A combined crossed beam and ab initio investigation on the reaction of carbon species with C4H6 isomers. I. The 1,3-butadiene molecule, H2CCHCHCH2(X1A')
Hahndorf, I.,Lee, H. Y.,Mebel, A. M.,Lin, S. H.,Lee, Y. T.,Kaiser, R. I.
, p. 9622 - 9636 (2007/10/03)
The reaction between ground state carbon atoms, C(3Pj), and 1,3-butadiene, H2CCHCHCH2, was studied at three averaged collision energies between 19.3 and. 38.8 kJmol-1 using the crossed molecular beam technique. Our experimental data combined with electronic structure calculations show that the carbon atom adds barrierlessly to the ?-orbital of the butadiene molecule via a loose, reactantlike transition state located at the centrifugal barrier. This process forms vinylcyclopropylidene which rotates in a plane almost perpendicular to the total angular momentum vector J around its C-axis. The initial collision complex undergoes ring opening to a long-lived vinyl-substituted triplet allene molecule. This complex shows three reaction pathways. Two distinct H atom loss channels form 1- and 3-vinylpropargyl radicals, HCCCHC2H3(X2A ) and H2CCCC2H3(X2A ), through tight exit transition states located about 20 kJmol-1 above the products; the branching ratio of 1- versus 3-vinylpropargyl radical is about 8:1. A minor channel of less than 10 percent is the formation of a vinyl, C2H3(X2A'), and propargyl radical C3H3(X2B2). The unambiguous identification of two C5H5 chain isomers under single collision has important implications to combustion processes and interstellar chemistry. Here, in denser media such as fuel flames and in circumstellar shells of carbon stars, the linear structures can undergo a collision-induced ring closure followed by a hydrogen migration to cyclic C5H5 isomers such as the cyclopentadienyl radical-a postulated intermediate in the formation of polycyclic aromatic hydrocarbons (PAHs).
Absolute Rate Constant and Product Branching Fractions for the Reaction between F and C2H4 at T = 202-298 K
Nesbitt, Fred L.,Thorn Jr., R. Peyton,Payne Jr., Walter A.,Tardy
, p. 4470 - 4479 (2007/10/03)
The discharge-flow kinetic technique coupled to mass-spectrometric detection has been used to determine the variable-temperature dependence of the rate constant and product branching fractions for the reaction between F(2P) and C2H4 at P = 1 Torr nominal pressure (He). The reaction was studied at T = 202 and 236 K by monitoring the decay of C2H4 in the presence of a large excess of F(2P). The overall rate coefficients were determined to be k1(202 K) = (1.7 ± 0.4) x 10-10 cm3 molecule-1 s-1 and k1(236 K) = (2.1 ± 0.5) x 10-10 cm3 molecule-1 s-1 with the quoted uncertainty representing total errors. Further, the branching fractions for the two observed reaction channels F + C2H4 → C2H3 + HF (1a) and F + C2H4 → C2H3F + H (1b) were determined by quantitatively measuring the yield of C2H3F under conditions of excess C2H4. The stabilized adduct, C2H4F, was not detected at T = 202 K. The derived branching fractions were Γ1a(202 K) = 0.25 ± 0.09, Γ1b (202 K) = 0.75 ± 0.16, and Γ1a(236 K) = 0.27 ± 0.13, and Γ1b (236 K) = 0.73 ± 0.20, where the quoted uncertainty represents total errors. By inclusion of k1(298 K) = (3.0 ± 0.8) x 10-10 cm3 molecule-1 s-1, a revised value that used data from our previous study and Γ1a(298 K) = 0.35 ± 0.04 and Γ1b (298 K) = 0.65 ± 0.04 from a laser photolysis/photoionization mass spectrometry study, we obtain the Arrhenius expressions k1a(T) = (7.5 ± 4.0) x 10-10 exp[(-1.2 ± 0.3)/(RT)] and k1b(T) = (5.2 ± 1.0) x 10-10 exp[(-0.6 ± 0.1)/(RT)] in units of cm3 molecule-1 s-1 for k and in units of kcal mol-1 for activation energy. The quoted uncertainty represents total errors at 1σ precision errors plus 15% systematic errors. RRKM calculations have shown that the critical energy for H addition to C2H3F is less than 6 kcal mol-1 larger than that for the addition of F to C2H4 and that the competitive decomposition of chemically activated C2H4F radicals favor C-H bond rupture by a factor greater than 1000 over that for C-F bond rupture.
Products of the ultraviolet photodissociation of trifluoroacetic acid and acrylic acid
Osborne, Michael C.,Li, Qiang,Smith, Ian W. M.
, p. 1447 - 1454 (2007/10/03)
The photodissociation of trifluoroacetic and acrylic acids by the ultraviolet light from a flashlamp has been investigated by measuring the relative yields of some of the major products by time-resolved infrared absorption using tunable, narrow band diode lasers. Yields of CO2 were measured both in the absence and presence of added O2. The former experiments measure the CO2 produced directly by decarboxylation of the acid, channel (2) below, the latter the sum of the yields from channels (1) and (2) since HOCO is rapidly converted to CO2. The yields of CO from the decarbonylation channel (3) have also been measured. For trifluoroacetic acid, the relative yields are found to be [HOCO]: [CO2]: [CO] = (0.28 ± 0.07): (0.61 ± 0.09): (0.11 ± 0.06) and, for acrylic acid, [HOCO]: [CO2]: [CO] = (0.32 ± 0.08): (0.37 ± 0.08) :(0.31 ± 0.09). The results are discussed in relation to the other, limited, measurements on the photodissociation of these acids and whether these three processes are likely to occur independently of one another.
Photodissociation of acrylonitrile at 193 nm: A photofragment translational spectroscopy study using synchrotron radiation for product photoionization
Blank, David A.,Suits, Arthur G.,Lee, Yuan T.,North, Simon W.,Hall, Gregory E.
, p. 5784 - 5794 (2007/10/03)
We have investigated the photodissociation of acrylonitrile (H2CCHCN) at 193 nm using the technique of photofragment translational spectroscopy. The experiments were performed at the Chemical Dynamics Beamline at the Advanced Light Source and used tunable vacuum ultraviolet synchrotron radiation for product photoionization. We have identified four primary dissociation channels including atomic and molecular hydrogen elimination. HCN elimination, and CN elimination. There is significant evidence that all of the dissociation channels occur on the ground electronic surface following internal conversion from the initially optically prepared state. The product translational energy distributions reflect near statistical simple bond rupture for the radical dissociation channels, while substantial recombination barriers mediate the translational energy release for the two molecular elimination channels. Photoionization onsets have provided additional insight into the chemical identities of the products and their internal energy content.
Crossed molecular beam study of the reaction O(3P) + allene
Schmoltner, A. M.,Huang, S. Y.,Brudzynski, R. J.,Chu, P. M.,Lee, Y. T.
, p. 1644 - 1653 (2007/10/02)
The reaction between ground state (3P) oxygen atoms and allene was studied under single collision conditions using the crossed molecular beams method.Product angular distributions and the translational energy distribution were determined for ea
Radical Analysis in the Pyrolysis of Hydrocarbons by Scavenging with Dimethyl Disulfide
Guthier, K.,Hebgen, P.,Loock, H. P.,Homann, K. H.,Zimmermann, G.,Hofmann, J.
, p. 140 - 142 (2007/10/02)
Radicals formed in the low pressure pyrolysis of hydrocarbons can be quantitatively analyzed by scavenging them with dimethyl disulfide (DMDS) in the condensed phase the pyrolyses of several hydrocarbons (ethyne, ethene, 1.3-butadiene, and benzene) have been studied in a flow reactor at 1300 K and 10.7 mbar.Samples of the hot gas mixture leaving the reactor were taken continuously by a quartz probe, the resulting supersonic nozzle beam was frozen together with an excess of DMDS on the inner surface of two hollow hemispheres cooled by liquid nitrogen.While melting the scavenging reaction takes place.The mixture of DMDS, stable pyrolysis products, and methylthio compounds was separated and identified with a GC-MS-system.CH3-radical, C2H3-radical, C6H5-radical radicals and H-atoms have been detected.The presence of acetone in ethyne pyrolysis has an important influence on the radical concentrations and the product yields.
