scholarly journals Reactions of NO<sub>3</sub> with aromatic aldehydes: gas-phase kinetics and insights into the mechanism of the reaction

2021 ◽  
Vol 21 (17) ◽  
pp. 13537-13551
Author(s):  
Yangang Ren ◽  
Li Zhou ◽  
Abdelwahid Mellouki ◽  
Véronique Daële ◽  
Mahmoud Idir ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rate Coefficient ◽  
Theoretical Calculations ◽  
Aromatic Aldehydes ◽  
Reaction Pathways ◽  
Rate Coefficients ◽  
Gas Phase Kinetics ◽  
No3 Radical ◽  
Temperature And Pressure ◽  
Mechanism Of The Reaction

Abstract. Rate coefficients for the reaction of NO3 radicals with a series of aromatic aldehydes were measured in a 7300 L simulation chamber at ambient temperature and pressure by relative and absolute methods. The rate coefficients for benzaldehyde (BA), ortho-tolualdehyde (O-TA), meta-tolualdehyde (M-TA), para-tolualdehyde (P-TA), 2,4-dimethyl benzaldehyde (2,4-DMBA), 2,5-dimethyl benzaldehyde (2,5-DMBA) and 3,5-dimethyl benzaldehyde (3,5-DMBA) were k1= 2.6 ± 0.3, k2= 8.7 ± 0.8, k3= 4.9 ± 0.5, k4= 4.9 ± 0.4, k5= 15.1 ± 1.3, k6= 12.8 ± 1.2 and k7= 6.2 ± 0.6, respectively, in the units of 10−15 cm3 molec.−1 s−1 at 298 ± 2 K. The rate coefficient k13 for the reaction of the NO3 radical with deuterated benzaldehyde (benzaldehyde-d1) was found to be half that of k1. The end product of the reaction in an excess of NO2 was measured to be C6H5C(O)O2NO2. Theoretical calculations of aldehydic bond energies and reaction pathways indicate that the NO3 radical reacts primarily with aromatic aldehydes through the abstraction of an aldehydic hydrogen atom. The atmospheric implications of the measured rate coefficients are briefly discussed.

scholarly journals Reactions of NO<sub>3</sub> with Aromatic Aldehydes: Gas Phase Kinetics and Insights into the Mechanism of the Reaction

2021 ◽  
Author(s):  
Yangang Ren ◽  
Li Zhou ◽  
Abdelwahid Mellouki ◽  
Véronique Daële ◽  
Mahmoud Idir ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rate Coefficient ◽  
Theoretical Calculations ◽  
Aromatic Aldehydes ◽  
Reaction Pathways ◽  
Rate Coefficients ◽  
Gas Phase Kinetics ◽  
No3 Radical ◽  
Temperature And Pressure ◽  
Mechanism Of The Reaction

Abstract. Rate coefficients for the reaction of NO3 radicals with a series of aromatic aldehydes were measured in a 7300 liter simulation chamber at ambient temperature and pressure by relative and absolute methods. The rate coefficients for benzaldehyde (BA), ortho-tolualdehyde (O-TA), meta-tolualdehyde (M-TA), para-tolualdehyde (P-TA), 2,4-dimethyl benzaldehyde (2,4-DMBA), 2,5-dimethyl benzaldehyde (2,5-DMBA) and 3,5-dimethyl benzaldehyde (3,5-DMBA) were: k1 = 2.6 ± 0.3, k2 = 8.8 ± 0.8, k3 = 4.8 ± 0.5, k4 = 4.9 ± 0.5, k5 = 15.1 ± 1.4, k6 = 12.7 ± 1.2 and k7 = 6.2 ± 0.6, respectively, in the units of 10−15 cm3 molecule−1 s−1 at 298 ± 2 K. The rate coefficient k13 for the reaction of the NO3 radical with deuterated benzaldehyde (benzaldehyde-d1) was found to be half that of k1. The end product of the reaction with an excess of NOx was measured to be C6H5C(O)O2NO2. Theoretical calculations of aldehydic bond energies and reaction pathways indicate that NO3 radical reacts with aromatic aldehydes through the abstraction of aldehydic hydrogen atom. The atmospheric implications of the measured rate coefficients are briefly discussed.

scholarly journals Pressure dependent low temperature kinetics for CN + CH3CN: competition between chemical reaction and van der Waals complex formation

2016 ◽  
Vol 18 (22) ◽  
pp. 15118-15132 ◽  
Author(s):  
Chantal Sleiman ◽  
Sergio González ◽  
Stephen J. Klippenstein ◽  
Dahbia Talbi ◽  
Gisèle El Dib ◽  
...  
Keyword(s):  
Low Temperature ◽  
Complex Formation ◽  
Gas Phase ◽  
Rate Coefficient ◽  
Flow Reactor ◽  
Slow Flow ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Low Temperature Kinetics ◽  
Temperature And Pressure

The gas phase reaction between the CN radical and acetonitrile CH3CN was investigated experimentally with a CRESU apparatus and a slow flow reactor as well as theoretically to explore the temperature and pressure dependence of its rate coefficient from 354 K down to 23 K.

scholarly journals Low temperature gas phase reaction rate coefficient measurements: Toward modeling of stellar winds and the interstellar medium

2019 ◽  
Vol 15 (S350) ◽  
pp. 382-383
Author(s):  
Niclas A. West ◽  
Edward Rutter ◽  
Mark A. Blitz ◽  
Leen Decin ◽  
Dwayne E. Heard
Keyword(s):  
Low Temperature ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Building Blocks ◽  
Rate Coefficients ◽  
Stellar Winds ◽  
Phase Reaction

AbstractStellar winds of Asymptotic Giant Branch (AGB) stars are responsible for the production of ∼85% of the gas molecules in the interstellar medium (ISM), and yet very few of the gas phase rate coefficients under the relevant conditions (10 – 3000 K) needed to model the rate of production and loss of these molecules in stellar winds have been experimentally measured. If measured at all, the value of the rate coefficient has often only been obtained at room temperature, with extrapolation to lower and higher temperatures using the Arrhenius equation. However, non-Arrhenius behavior has been observed often in the few measured rate coefficients at low temperatures. In previous reactions studied, theoretical simulations of the formation of long-lived pre-reaction complexes and quantum mechanical tunneling through the barrier to reaction have been utilized to fit these non-Arrhenius behaviours of rate coefficients.Reaction rate coefficients that were predicted to produce the largest change in the production/loss of Complex Organic Molecules (COMs) in stellar winds at low temperatures were selected from a sensitivity analysis. Here we present measurements of rate coefficients using a pulsed Laval nozzle apparatus with the Pump Laser Photolysis - Laser Induced Fluorescence (PLP-LIF) technique. Gas flow temperatures between 30 – 134 K have been produced by the University of Leeds apparatus through the controlled expansion of N2 or Ar gas through Laval nozzles of a range of Mach numbers between 2.49 and 4.25.Reactions of interest include those of OH, CN, and CH with volatile organic species, in particular formaldehyde, a molecule which has been detected in the ISM. Kinetics measurements of these reactions at low temperatures will be presented using the decay of the radical reagent. Since formaldehyde and the formal radical (HCO) are potential building blocks of COMs in the interstellar medium, low temperature reaction rate coefficients for their production and loss can help to predict the formation pathways of COMs observed in the interstellar medium.

scholarly journals Gas phase kinetics of the OH + CH3CH2OH reaction at temperatures of the interstellar medium (T = 21–107 K)

2018 ◽  
Vol 20 (8) ◽  
pp. 5865-5873 ◽  
Author(s):  
A. J. Ocaña ◽  
S. Blázquez ◽  
B. Ballesteros ◽  
A. Canosa ◽  
M. Antiñolo ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
Rate Coefficients ◽  
Cold Temperatures ◽  
Gas Phase Kinetics ◽  
P Rate ◽  
Kinetics Of

Rate coefficients for the OH-reaction with ethanol, ubiquitous in the interstellar medium, has been determined at ultra-cold temperatures by using the pulsed and continuous CRESU technique.

Theoretical Prediction of CH3O and CH2OH Gas-Phase Decomposition Rate Coefficients

1986 ◽  
Vol 39 (12) ◽  
pp. 1929 ◽  
Author(s):  
PG Greenhill ◽  
BV Ogrady ◽  
RG Gilbert
Keyword(s):  
High Pressure ◽  
Theoretical Prediction ◽  
Gas Phase ◽  
Decomposition Rate ◽  
Rate Coefficient ◽  
Rate Coefficients ◽  
Phase Decomposition ◽  
Kinetic Schemes ◽  
Theoretical Predictions ◽  
Temperature Dependences

Theoretical predictions are made for the pressure and temperature dependences of two reactions involved in methanol combustion: (A) CH3O → CH2O + H and (B) CH2OH → CH2O + H. The calculations are carried out by using RRKM theory with a Gorin model for the activated complexes, with fall-off effects being taken into account by using the master equation. Results for the high-pressure rate coefficients (s-1) are (A) 3×1014 exp(-108 kJ mol-1 /RT), (B) 7×1014 exp(-124 kJ mol-1 /RT) at 1000 K. For the low-pressure limiting rate coefficient (cm3 s-1) over the range 600- 1000 K (A) 8×10-9 exp(-90 kJ mol-1 /RT); (B) 2×10-8 exp(-108 kJ mol-1 /RT). At 1000 K, the pressure at which the fall-off rate coefficients are one-half of their limiting high-pressure values are 3x108 Pa for both reactions. Formulae for inclusion of these reactions (including fall- off effects) over the range 300-2000 K and 10-2-106 Pa in modelling complex kinetic schemes are presented.

The kinetics of the pyrolysis of Cyclohexyl chloride.

1958 ◽  
Vol 11 (3) ◽  
pp. 314 ◽  
Author(s):  
ES Swinbourne
Keyword(s):  
Gas Phase ◽  
Hydrogen Chloride ◽  
Rate Coefficient ◽  
Initial Pressure ◽  
Order Reaction ◽  
Rate Coefficients ◽  
Homogeneous Reaction ◽  
First Order ◽  
Induction Periods ◽  
Kinetics Of

cycloHexy1 chloride has been shown to decompose in the gas phase at 318-385 �C almost exclusively to cyclohexene and hydrogen chloride. With clean glass-walled reactors the reaction was largely heterogeneous, but after the walls were coated with a carbonaceous film a homogeneous first-order reaction was found to predominate. For initial pressures within the range 4-40 cm mercury the rate coefficients for the homogeneous reaction were expressible as������� k = 5.88 x 1013exp(-50,000 cal/RT) sec-1. There was some evidence for the rate coefficient becoming pressure-dependent below 5-10 mm initial pressure of reactant. The reaction exhibited no induction periods and the velocity was virtually unaffected by the addition of large amounts of propene or cyclohexene and traces of chlorine or bromine. The results were consistent with a unimolecular elimination of hydrogen chloride.

Reaction of •OH with CHCl=CH-CHF2 and its atmospheric implication for future environmental-friendly refrigerant

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olivier Holtomo ◽  
Lydia Rhyman ◽  
Mama Nsangou ◽  
Ponnadurai Ramasami ◽  
Ousmanou Motapon
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
Radiative Forcing ◽  
Rate Coefficient ◽  
Computational Method ◽  
Rate Coefficients ◽  
Ir Absorption ◽  
Geometrical Structures ◽  
Atmospheric Lifetime ◽  
Environmental Friendly

Abstract In order to understand the atmospheric implication of the chlorinated hydrofluoroolefin (HFO), the geometrical structures and the IR absorption cross sections of the stereoisomers 1-chloro-3,3-difluoropropene were studied using the B3LYP/6-31G(3df) and M06-2X/6-31G(3df) methods in the gas phase. The cis-trans isomerization was assessed using the M06-2X/6-311++G(3df,p)//6-31+G(3df,p) method. The latter method was also employed for thermochemistry and the rate coefficients of the reactions of •OH with the cis- and trans-isomers in the temperature ranging from 200 to 400 K. The computational method CCSD/cc-pVTZ//M06-2X/6-31+G(3df,p) was used to benchmark the rate coefficients. It turns out that, the trans-isomer is more stable than cis-isomer and the trans- to cis-isomerization is thermodynamically unfavorable. The rate coefficient follows the Gaussian law with respect to the inverse of temperature. At the global temperature of stratosphere, the calculated rate coefficients served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). This yielded lifetimes of 4.31 and 7.31 days and POCPs of 3.80 and 2.23 for the cis- and trans-isomer, respectively. The radiative forcing efficiencies gave 0.0082 and 0.0152 W m−2 ppb−1 for the cis- and trans-isomer, respectively. The global warming potential approached zero for both stereoisomers at 20, 100, and 500 years time horizons.

Gas-Phase Kinetics of the Self Reactions of the Radicals CH2F and CHF2

2000 ◽  
Vol 214 (5) ◽  
Author(s):  
T. Beiderhase ◽  
Walter Hack ◽  
Karlheinz Hoyermann ◽  
Matthias Olzmann
Keyword(s):  
Gas Phase ◽  
Molecular Beam ◽  
Rate Coefficient ◽  
Flow Reactor ◽  
Main Channel ◽  
Low Energy ◽  
The Self ◽  
Gas Phase Kinetics ◽  
Low Energy Electron ◽  
Kinetics Of

Fluorinated hydrocarbon radical-radical reactions in the gas phase have been studied at low pressure (0.5 ≤ p/mbar ≤ 2) and low temperature (253 ≤ T/K ≤ 333) using the discharge flow reactor molecular beam sampling mass spectrometry (MS) technique. Stable and labile species have been detected by MS applying low energy electron impact as well as multiphoton ionisation.For the combination reactionCHthe rate coefficient kCHis the main channel (k(1b)/kFor the CHFCHFthe rate coefficient was measured as kNo pressure dependence of k

scholarly journals A self-consistent, multivariate method for the determination of gas-phase rate coefficients, applied to reactions of atmospheric VOCs and the hydroxyl radical

2018 ◽  
Vol 18 (6) ◽  
pp. 4039-4054 ◽  
Author(s):  
Jacob T. Shaw ◽  
Richard T. Lidster ◽  
Danny R. Cryer ◽  
Noelia Ramirez ◽  
Fiona C. Whiting ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Rate Coefficient ◽  
Relative Rate ◽  
Ambient Air ◽  
Rate Coefficients ◽  
Oxidation Reactions ◽  
Simultaneous Study ◽  
The University ◽  
Good Agreement

Abstract. Gas-phase rate coefficients are fundamental to understanding atmospheric chemistry, yet experimental data are not available for the oxidation reactions of many of the thousands of volatile organic compounds (VOCs) observed in the troposphere. Here, a new experimental method is reported for the simultaneous study of reactions between multiple different VOCs and OH, the most important daytime atmospheric radical oxidant. This technique is based upon established relative rate concepts but has the advantage of a much higher throughput of target VOCs. By evaluating multiple VOCs in each experiment, and through measurement of the depletion in each VOC after reaction with OH, the OH + VOC reaction rate coefficients can be derived. Results from experiments conducted under controlled laboratory conditions were in good agreement with the available literature for the reaction of 19 VOCs, prepared in synthetic gas mixtures, with OH. This approach was used to determine a rate coefficient for the reaction of OH with 2,3-dimethylpent-1-ene for the first time; k =  5.7 (±0.3)  ×  10−11 cm3 molecule−1 s−1. In addition, a further seven VOCs had only two, or fewer, individual OH rate coefficient measurements available in the literature. The results from this work were in good agreement with those measurements. A similar dataset, at an elevated temperature of 323 (±10) K, was used to determine new OH rate coefficients for 12 aromatic, 5 alkane, 5 alkene and 3 monoterpene VOC + OH reactions. In OH relative reactivity experiments that used ambient air at the University of York, a large number of different VOCs were observed, of which 23 were positively identified. Due to difficulties with detection limits and fully resolving peaks, only 19 OH rate coefficients were derived from these ambient air samples, including 10 reactions for which data were previously unavailable at the elevated reaction temperature of T =  323 (±10) K.

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