2597-44-6Relevant articles and documents
Evaluation of the rate constant for the reaction OH+H2CO: Application of modeling and sensitivity analysis techniques for determination of the product branching ratio
Yetter, Richard A.,Rabitz, Herschel,Dryer, Frederick L.,Maki, Robert G.,Klemm, R. Bruce
, p. 4088 - 4097 (1989)
Novel modeling and sensitivity analysis techniques are used with experimental data obtained from discharge flow-resonance fluorescence experiments to evaluate the product branching ratio of OH + H2CO.Two channels are considered: the H-atom abstraction reaction (R2) to form HCO and H2O; and the addition reaction ( R 17 ) followed by rearrangement and decomposition to form HCOOH and H.The rate constant values obtained at 298 K are kR2 = (7.75+/-1.24) X 10-12 cm3/molecule s and kR17= (0.2-0.2+0.8) X 10-12 cm3/molecule s.The results demonstrate that the reaction proceeds almost exclusively via the H-atom abstraction pathway.
KINETICS OF POLYATOMIC FREE RADICALS PRODUCED BY LASER PHOTOLYSIS. 3. REACTION OF VINYL RADICALS WITH MOLECULAR OXYGEN.
Slagle,Park,Heaven,Gutman
, p. 4356 - 4361 (1984)
The kinetics and mechanism of the gaseous reaction of vinyl radicals with molecular oxygen have been studied between 297 and 602 K. The radicals were produced in a heated tubular reactor by the pulsed laser photolysis of C//2H//3Br at 193 nm. Reactant and product concentrations were monitored in real-time experiments using photoionization mass spectrometry. The products formed in this temperature range are HCO and H//2CO. The overall rate constant is pressure independent and is nearly constant with temperature: k equals 6. 6 ( plus or minus 1. 3) multiplied by 10** minus **1**2 exp(250 plus or minus 100 cal/RT) cm**3 molecule** minus **1 s** minus **1. The magnitude of the rate constant, its temperature and pressure dependence, and the identity of the products of this reaction indicate that it proceeds by an addition mechanism in which the adduct rapidly rearranges to form an energy-rich dioxetanyl intermediate which decomposes into the observed products. Two other reactions (C//2H//3 plus i-C//4H//1//0 and C//3H//5 (allyl radical) plus O//2) were investigated at elevated temperatures, but no reaction was detected.
ESR study of low-temperature radiolysis and photolysis of substituted N′-furfurylidenebenzhydrazides
Gordon,Chuev,Aldoshin,Mikhailov
, p. 2055 - 2059 (1999)
Low-temperature (77 K) γ- and UV irradiation of substituted N′-furfurylidenebenzhydrazides produces paramagnetic particles in radiation-chemical yields of (0.05-0.5)/100 eV and quantum yields of 4 · 10-5-10-3, respectively. ESR study showed that hydrazyl radicals and HC- O and N -O2 are the main products of radiolysis and photolysis, and the latter decay upon heating of the sample to 190 K, whereas the hydrazyl radicals survive up to 423 K. Further heating results in thermodestruction of the hydrazides, and the ESR spectrum exhibits only a singlet with splitting at 1 mT, which is characteristic of polyconjugated compounds.
Kinetic Study of the NO3-CH2O Reaction and Its Possible Role in Nighttime Tropospheric Chemistry
Cantrell, Christopher A.,Stockwell William R.,Anderson, Larry G.,Busarow, Kerry L.,Perner, Dieter,et al.
, p. 139 - 146 (1985)
The kinetics of the reaction NO3 + CH2O -> HONO2 + HCO (14) have been studied by using in situ, long-path (170 m), infrared and visible spectroscopy to follow the reactants and products in dilute mixtures of O3, NO2, and CH2O in N2/O2 at 700 torr (25 +/- 2 deg C).The concentrations of O3, NO2, CH2O, N2O5, CO, HONO2, and HCO2H were detrmined as a function of time through their characteristic infrared absorption bands by using a Fourier transform infrared spectrometer system.The concentrations of NO3 and NO2 were followed by using the characteristic visible absorption bands monitored by a differential optical absorption spectrometer.The kinetic data were analyzed by using both rates of product formation (CO) and reactant removal (N2O5, NO3, CH2O) and computer simulations of the complex reactions which follow reaction 14 in these systems.The reults show that the use alone of N2O5 decay rates in the presence and absence of CH2O to derive k14 estimates can lead to significant error as a result of the generation of secondary radicals (HO2, HO) following the primary reaction 14 and the subsequent reactions of HO with CH2O and HO2 with NO3.The present data provide the estimate k14 = (6.3 +/- 1.1)*10-16 cm3 molecule-1 s-1 (25 +/- 2 deg C).
Kinetics of the reactions of vinyl radicals with molecular oxygen and chlorine at temperatures 200-362 K
Eskola,Timonen
, p. 2557 - 2561 (2003)
The kinetics of the C2H3 + O2 and C2H3 + Cl2 reactions have been studied in direct measurements at temperatures between 200-362 K using a tubular flow reactor coupled to a photoionization mass spectrometer (PIMS). The vinyl radicals were homogeneously generated by the pulsed laser photolysis of methyl vinyl ketone at 193 nm. The subsequent decays of the radical concentrations were monitored in time-resolved measurements to obtain the reaction rate coefficients under pseudo-first-order conditions. Reaction products identified were HCO and H2CO for the oxygen reaction and C2H3Cl for the chlorine reaction, respectively. The rate coefficients of both reactions were independent of the bath gases (He or N2) and pressures within the experimental range, 0.13-0.53 kPa, and can be expressed by the Arrhenius equations k(C2H3 + O2) = (4.62 ± 0.40) × 10-12 exp(1.41 ± 0.18 kJ mol-1/RT) cm3 molecule-1 s-1 and k(C2H3 + Cl2) = (4.64 ± 0.59) × 10-12 exp(3.12 ± 0.27 kJ mol-1/RT) cm3 molecule-1 s-1, where uncertainties are one standard deviation. These experimental results obtained by using our new apparatus are in good agreement with previous direct measurements.
Formation of HO2 from OH and C2H2 in the presence of O2
Bohn, Birger,Zetzsch, Cornelius
, p. 1203 - 1210 (1998)
Pulsed production of OH in a gas-phase system containing acetylene, O2 and NO resulted in biexponential OH-decay curves, indicating formation of HO2 in secondary reactions.Production and detection of OH were performed by 248 nm photolysis of H2O2 and cw-laser long-path absorption at 308 nm, respectively.Measurements were made at room temperature in O2 or N2-O2 mixtures containing 5percent O2 at total pressures between 10 and 100 kPa.Analysis of the decay curves resulted in effective rate constants for the removal of OH and the formation of HO2 by acetylene in the presence of O2 in the range (1.4-3.5) x 10-13 cm3 s-1, dependent on total pressure and O2 concentration.HO2 is thought to be formed from HCO and O2, with HCO originating in a reaction of an intermediate acetylene-OH adduct with O2.HO2 yields were found to vary between 1.13 and 1.01 and tending to higher values at lower total pressures.These yields are higher than the expected value of 1, which can be explained by a dissociation of a small fraction of vibrationally excited glyoxal formed, together with OH in a second channel of the acetylene-OH adduct + O2 reaction.In order to check whether the increased HO2 yields are real, CO was used instead of acetylene.In this case, an HO2 yield of 0.99 was found, in good agreement with expectations, and a rate constant of (1.66 +/- 0.25) x 10-13 cm3 s-1 for the OH + CO reaction in 20 kPa O2 was determined.In addition, a rate constant for the HO2 + NO reaction of (9.5 +/- 1.5) x 10-12 cm3 s-1, rate constants for the OH + NO reaction in the range (1.3-7.4) x 10-12 cm3 s-1, depending on total pressure, and upper limits for the rate constants of possible reactions HO2 + C2H2 (k =-15 cm3 s-1) and HO2 + CO (k =-15 cm3 s-1) were derived.Error limits include statistical (2?) and possible systematic errors.
Accessing the Nitromethane (CH3NO2) Potential Energy Surface in Methanol (CH3OH)-Nitrogen Monoxide (NO) Ices Exposed to Ionizing Radiation: An FTIR and PI-ReTOF-MS Investigation
Góbi, Sándor,Crandall, Parker B.,Maksyutenko, Pavlo,F?rstel, Marko,Kaiser, Ralf I.
, p. 2329 - 2343 (2018/03/21)
(D3-)Methanol-nitrogen monoxide (CH3OH/CD3OH-NO) ices were exposed to ionizing radiation to facilitate the eventual determination of the CH3NO2 potential energy surface (PES) in the condensed phase. R
Photo-tautomerization of acetaldehyde to vinyl alcohol: A potential route to tropospheric acids
Andrews, Duncan U.,Heazlewood, Brianna R.,Maccarone, Alan T.,Conroy, Trent,Payne, Richard J.,Jordan, Meredith J. T.,Kable, Scott H.
, p. 1203 - 1206 (2012/10/29)
Current atmospheric models underestimate the production of organic acids in the troposphere. We report a detailed kinetic model of the photochemistry of acetaldehyde (ethanal) under tropospheric conditions. The rate constants are benchmarked to collision-free experiments, where extensive photo-isomerization is observed upon irradiation with actinic ultraviolet radiation (310 to 330 nanometers). The model quantitatively reproduces the experiments and shows unequivocally that keto-enol photo-tautomerization, forming vinyl alcohol (ethenol), is the crucial first step. When collisions at atmospheric pressure are included, the model quantitatively reproduces previously reported quantum yields for photodissociation at all pressures and wavelengths. The model also predicts that 21 ± 4% of the initially excited acetaldehyde forms stable vinyl alcohol, a known precursor to organic acid formation, which may help to account for the production of organic acids in the troposphere.
