Rate and Equilibrium Constant of the Reaction of 1-Methylvinoxy Radicals with O2:  CH3COCH2 + O2 ↔ CH3COCH2O2

Hassouna, Mnasser; Delbos, Eric; Devolder, P.; Viskolcz, Béla; Fittschen, Christa

doi:10.1021/jp0558270

Cited by 27 publications

(55 citation statements)

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“…The initial reaction is a 1,5 H-shift from the methyl group with an MC-TST calculated rate coefficient of 5.9 × 10 -6 s -1 . The high barrier resulting in low rate coefficient for this reaction is in agreement with previous studies 17, [72][73][74][75] and has been ascribed to the strain in the TS induced by the sp 2 -hybridized carbon atom reducing the flexibility. 72 This means that the 1,5 H-shift is negligible from the thermalized peroxy radical under all relevant time scales and any possible OH-recycling from reactions following this Hshift thus relies on it occurring via excess energy from the O2-addition to the CH3C(O)CH2O2…”

Section: Reactionsupporting

confidence: 91%

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Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

et al. 2020

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Pulsed laser photolysis coupled with infrared (IR) wavelength modulation spectroscopy and ultraviolet (UV) absorption spectroscopy was used to study the kinetics and branching fractions for the acetonyl peroxy (CH3C(O)CH2O2) self-reaction and its reaction with hydro peroxy (HO2) at a temperature of K and pressure of 100 Torr. Near-IR and mid-IR lasers simultaneously monitored HO2 and hydroxyl, OH, respectively, while UV absorption measurements monitored the CH3C(O)CH2O2 concentrations. The overall rate constant for the reaction between CH3C(O)CH2O2 and HO2 was found to be (5.5 ± 0.5) × 10-12 cm 3 molecule-1 s-1 and the branching fraction for OH yield from this reaction was directly measured as 0.30 ± 0.04. The CH3C(O)CH2O2 self-reaction rate constant was measured to be (4.8 ± 0.8) × 10-12 cm 3 molecule-1 s-1 and the branching fraction for alkoxy formation was inferred from secondary chemistry as 0.33 ± 0.13. An increase in the rate of the HO2 self-reaction was also observed as a function of acetone (CH3C(O)CH3) concentration which is interpreted as a chaperone effect resulting from hydrogen-bond complexation between HO2 and CH3C(O)CH3. The chaperone enhancement coefficient for CH3C(O)CH3 was determined to be k²A = (4.0 ± 0.2) ´ 10-29 cm 6 molecule-2 s-1 and the equilibrium constant for HO2•CH3C(O)CH3 complex formation was found to be Kc(R15) = (2.0 ± 0.89) × 10-18 cm 3 molecule-1 ; from these values the rate constant for the HO2 + HO2•CH3C(O)CH3 reaction was estimated to be (2 ± 1) × 10-11 cm 3 molecule-1 s-1. Results from UV absorption cross-section measurements of CH3C(O)CH2O2 and prompt OH radical yields arising from possible oxidation of the CH3C(O)CH3-derived alkyl radical are also discussed. Using theoretical methods, no likely pathways for the observed prompt OH radical formation have been found and thus remains unexplained.

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Section: Reactionsupporting

confidence: 91%

“…However, there is currently no evidence for a mechanism for OH generation from this reaction based on the theoretical work reported here as well as in recent studies. 17,[72][73][74] The Cl + HO2 reaction cannot resolve the discrepancy because prompt OH is observed when investigating the CH3C(O)CH2O2…”

Section: Ch3c(o)ch2o2 + Oh → Ho2 + Ch3c(o)ch2o (R17)mentioning

confidence: 99%

Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

et al. 2020

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“…The rate constants for k 3a and k 3b are assumed to be equal to that measured for the reaction of O 2 with the acetonyl (1-methylvinoxy) radical [(1.00 ( 0.25) × 10 -12 cm 3 molecule -1 s -1 at ambient temperature and 760 Torr]. [16][17][18] Data in Figure 4 of ref 17 indicate that, in the high-pressure limit, there is little temperature dependence to the addition reaction of O 2 to the acetonyl radical. Therefore, we have assumed zero activation energy for reactions 3a and 3b.…”

Section: Computer Modeling Of the Datamentioning

confidence: 99%

Products and Mechanism of the Reaction of Chlorine Atoms with 3-Pentanone in 700−950 Torr of N₂/O₂ Diluent at 297−515 K

2009

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The products, kinetics, and mechanism of the reaction Cl + 3-pentanone have been measured by UV irradiation of Cl(2)/3-pentanone/N(2) (O(2)) mixtures using primarily GC analysis with selected cross checks by FTIR. In the absence of O(2), the products are 1- and 2-chloro-3-pentanone with yields of 21 and 78%, respectively. As the temperature is increased, the yield of 1-chloro-3-pentanone increases modestly relative to the 2-chloro-3-pentanone yield. On the basis of this increase, the activation energy for hydrogen abstraction at the 1 position is determined to be 500 (+/-500) cal mole(-1) relative to abstraction at the 2 position. In the presence of 500 ppm of O(2) with 900-1000 ppm of Cl(2) at 297 K, the yield of 2-chloro-3-pentanone decreases dramatically from 78 to 2.5%, while the 1-chloro-3-pentanone decreases only modestly from 21 to 17%. The observed oxygenated species are acetaldehyde (59%), 2,3-pentanedione (9%), and propionyl chloride (56%). Increasing the temperature to 420 K (O(2) = 500 ppm) suppresses these oxygenated products, and 2-chloro-3-pentanone again becomes the primary product, indicating that the O(2) addition reaction to the 2-pentanonyl radical has become reversible. At 500 K and 10 000 ppm O(2), a new product channel opens which forms a small yield ( approximately 4%) of ethylvinylketone. Computer modeling of the product yields has been performed to gain an understanding of the overall reaction mechanism in the presence and absence of O(2). The reaction of chlorine atoms with 3-pentanone proceeds with a rate constant of 8.1 (+/-0.8) x 10(-11) cm(3) molecule(-1) s(-1) independent of temperature over the range of 297-490 K (E(a) = 0 +/- 200 cal mole(-1)). Rate constant ratios of k(C(2)H(5)C(O)CHCH(3) + Cl(2))/k(C(2)H(5)C(O)CHCH(3) + O(2)) = 0.0185 +/- 0.0037 and k(C(2)H(5)C(O)CH(2)CH(2) + Cl(2))/k(C(2)H(5)CH(2)C(O)CH(2)CH(2) + O(2)) = 2.7 +/- 0.4 were determined at 297 K in 800-950 Torr of N(2)/O(2) diluent. In 800-950 Torr of N(2)/O(2) diluent, the major fate of the alkoxy radical CH(3)CH(O)C(O)C(2)H(5) is decomposition to give C(2)H(5)C(O) radicals and CH(3)CHO. These results show that the chemical mechanisms of the 3-pentanone reactions are very similar to those observed for butanone. In addition, the rate constants of the reactions of chlorine atoms with 1-chloro-3-pentanone [3 (+/-0.6) x 10(-11) over the range of 297-460 K], 2,3-pentanedione [1.4 (+/-0.3) x 10(-11) at 297 K], and ethylvinylketone [1.9 (+/-0.4) x 10(-10) over the range of 297-400 K, decreasing rapidly above 400 K] were measured at ambient pressure.

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“…The abstraction product acetonyl radical is also an important intermediate species that yields peroxy radicals through the reaction with O 2 [7,8]. From the environmental point of view strongly linked with the depletion of the ozone layer, Carr et al investigated the gas-phase reaction of the OH radical with halogenated acetones and determined the rate constants at 298 K [9].…”

Section: Introductionmentioning

confidence: 99%

Computational study of the reaction between chloroacetone and OH radical

Tanaka

Yamagishi

Nishikiori

2013

Computational and Theoretical Chemistry

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In this study, the reaction of the chloroacetone with OH radical was studied theoretically using density functional theory (DFT) and transition state theory. The potential energy surface of the reaction was calculated at the CAM-B3LYP/6-311++G(2d,2p) and M06-2X/6-311++G(2d,2p) levels. We initially considered four possible reaction paths: (1) the hydrogen atom abstraction from chloroacetone by OH radical; (2) the addition of the OH radical to the carbonyl carbon; (3) chlorine atom abstraction; and (4) S N 2 displacement. The conventional transition state theory was employed to calculate the rate constants. The hydrogen abstraction from the -CH 2 Cl group was found to be dominant. Since, the predicted total rate constant at the CAM-B3LYP/6-311++G(2d,2p) level was in good agreement with the experimental value at 298 K, the level of theory used in this study to describe this reaction is appropriate.

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Rate and Equilibrium Constant of the Reaction of 1-Methylvinoxy Radicals with O₂: CH₃COCH₂ + O₂ ↔ CH₃COCH₂O₂

Cited by 27 publications

References 26 publications

Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

Products and Mechanism of the Reaction of Chlorine Atoms with 3-Pentanone in 700−950 Torr of N₂/O₂ Diluent at 297−515 K

Computational study of the reaction between chloroacetone and OH radical

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Rate and Equilibrium Constant of the Reaction of 1-Methylvinoxy Radicals with O2: CH3COCH2 + O2 ↔ CH3COCH2O2

Cited by 27 publications

References 26 publications

Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

Products and Mechanism of the Reaction of Chlorine Atoms with 3-Pentanone in 700−950 Torr of N2/O2 Diluent at 297−515 K

Computational study of the reaction between chloroacetone and OH radical

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Rate and Equilibrium Constant of the Reaction of 1-Methylvinoxy Radicals with O₂: CH₃COCH₂ + O₂ ↔ CH₃COCH₂O₂

Products and Mechanism of the Reaction of Chlorine Atoms with 3-Pentanone in 700−950 Torr of N₂/O₂ Diluent at 297−515 K