Reactions of oxygen atoms with hydrocarbon radicals: a priori kinetic predictions for the CH3+ O, C2H5+ O, and C2H3+ O reactions

Harding, Lawrence B.; Klippenstein, Stephen J.; Georgievskii, Yuri

doi:10.1016/j.proci.2004.08.184

Cited by 52 publications

(49 citation statements)

References 41 publications

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“…Among these, the reaction O + CH 3 CH 2 → CH 3 CHO + H (Charnley et al 1992;Harding et al 2005;Yang et al 2005) is the most efficient in the conditions appropriate for the L1157-B1 gas. Therefore, the two gaseous species necessary to synthesise acetaldehyde are atomic oxygen and ethyl radical.…”

Section: Discussionmentioning

confidence: 99%

Seeds of Life in Space (SOLIS)

Codella

Ceccarelli

Caselli

et al. 2017

A&A

108

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Context. Modern versions of the Miller-Urey experiment claim that formamide (NH 2 CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming solar-type stars and in external galaxies. Aims. How NH 2 CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods. We used the NOrthern Extended Millimeter Array (NOEMA) interferometer to image NH 2 CHO towards the L1157-B1 blue-shifted shock, a well-known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results. We report the first spatially resolved image (size ∼9 , ∼2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM 5 km s −1 . A column density of N NH 2 CHO = 8 × 10 12 cm −1 and an abundance, with respect to H-nuclei, of 4 × 10 −9 are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by a gas-phase chemical process and not on grain surfaces as previously suggested. Conclusions. The Seeds of Life in Space (SOLIS) interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas phase around Sun-like protostars.

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Section: Discussionmentioning

confidence: 99%

Seeds of Life in Space (SOLIS)

Codella

Ceccarelli

Caselli

et al. 2017

A&A

108

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“…An additional reaction channel (R22) was introduced in their work, with a branching ratio of 0.21, 0.67 and 0.12 for (R20), (R21), (R22). The total reaction rate of C 2 H 5 + O varied in different investigations [75,83,93,94]. Comparatively high value was proposed by Tsang and Hampson [93] and Herron [94] (9.6 Â 10 13 and 1.3 Â 10 14 , respectively).…”

Section: Reactions Of Ethyl Radicalmentioning

confidence: 93%

“…Comparatively high value was proposed by Tsang and Hampson [93] and Herron [94] (9.6 Â 10 13 and 1.3 Â 10 14 , respectively). Later studies suggested slower reaction rates, 6.62 Â 10 13 by Baulch et al [83] and around 3.19 Â 10 13 in the work of Harding et al [75]. The reaction between ethyl radical and molecular oxygen was also included in this model (R23) and (R24).…”

Section: Reactions Of Ethyl Radicalmentioning

confidence: 94%

“…Reaction between methyl radical and O atom (R5) and (R6) was theoretically investigated in the work of Harding et al [75]. A competitive additional channel (R6) was suggested with a branching ratio of 0.18, while only (R5) was considered in USC Mech II [35] and GRI Mech 3.0 [34].…”

Section: Submechanism Of Methanementioning

confidence: 99%

“…Oxidation reactions between O atom and ethyl radical (R20), (R21), (R22) were updated in this model with the calculation of Harding et al [75]. An additional reaction channel (R22) was introduced in their work, with a branching ratio of 0.21, 0.67 and 0.12 for (R20), (R21), (R22).…”

Section: Reactions Of Ethyl Radicalmentioning

confidence: 99%

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The mechanism for the C 2 H 3 + CH 3 OH reaction has been investigated by the Gaussian-4 (G4) method based on the geometric parameters of the stationary points optimized at the B3LYP/6-31G(2df, p) level of theory. Four transition states have been identified for the production of C 2 H 4 + CH 3 O (TSR/P1), C 2 H 4 + CH 2 OH (TSR/P2), C 2 H 3 OH + CH 3 (TSR/P3), and C 2 H 3 OCH 3 + H (TSR/P4) with the corresponding barriers 8.48, 9.25, 37.62, and 34.95 kcal/mol at the G4 level of theory, respectively. The rate constants and branching ratios for the two lower energy H-abstraction reactions were calculated using canonical variational transition state theory with the Eckart tunneling correction at the temperature range 300-2500 K. The predicted rate constants have been compared with existing literature data, and the uncertainty has been discussed. The branching ratio calculation suggests that the channel producing CH 3 O is dominant up to about 1070 K, above which the channel producing CH 2 OH becomes very competitive. C 2015 Wiley Periodicals, Inc. Int J Chem Kinet 47: [764][765][766][767][768][769][770][771][772] 2015

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Reactions of oxygen atoms with hydrocarbon radicals: a priori kinetic predictions for the CH3+ O, C2H5+ O, and C2H3+ O reactions

Cited by 52 publications

References 41 publications

Seeds of Life in Space (SOLIS)

Seeds of Life in Space (SOLIS)

Kinetic modeling study of benzene and PAH formation in laminar methane flames

A Computational Study of the Kinetics and Mechanism for the C₂H₃+ CH₃OH Reaction

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Reactions of oxygen atoms with hydrocarbon radicals: a priori kinetic predictions for the CH3+ O, C2H5+ O, and C2H3+ O reactions

Cited by 52 publications

References 41 publications

Seeds of Life in Space (SOLIS)

Seeds of Life in Space (SOLIS)

Kinetic modeling study of benzene and PAH formation in laminar methane flames

A Computational Study of the Kinetics and Mechanism for the C2H3+ CH3OH Reaction

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Product

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A Computational Study of the Kinetics and Mechanism for the C₂H₃+ CH₃OH Reaction