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Low-Temperature Kinetic Isotope Effects in CH 3 OH + H → CH 2 OH + H 2 Shed Light on the Deuteration of Methanol in Space.
- Source :
-
The journal of physical chemistry. A [J Phys Chem A] 2019 Oct 24; Vol. 123 (42), pp. 9061-9068. Date of Electronic Publication: 2019 Oct 14. - Publication Year :
- 2019
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Abstract
- We calculated reaction rate constants including atom tunneling for the hydrogen abstraction reaction CH <subscript>3</subscript> OH + H → CH <subscript>2</subscript> OH + H <subscript>2</subscript> with the instanton method. The potential energy was fitted by a neural network that was trained to UCCSD(T)-F12/VTZ-F12 data. Bimolecular gas-phase rate constants were calculated using microcanonic instanton theory. All H/D isotope patterns on the CH <subscript>3</subscript> group and the incoming H atom are studied. Unimolecular reaction rate constants, representing the reaction on a surface, down to 30 K, are presented for all isotope patterns. At 30 K, they range from 4100 for the replacement of the abstracted H by D to ∼8 for the replacement of the abstracting H to ∼2 to 6 for secondary KIEs. The <superscript>12</superscript> C/ <superscript>13</superscript> C kinetic isotope effect is 1.08 at 30 K, while the <superscript>16</superscript> O/ <superscript>18</superscript> O kinetic isotope effect is extremely small. A simple kinetic surface model using these data predicts high abundances of the deuterated forms of methanol.
Details
- Language :
- English
- ISSN :
- 1520-5215
- Volume :
- 123
- Issue :
- 42
- Database :
- MEDLINE
- Journal :
- The journal of physical chemistry. A
- Publication Type :
- Academic Journal
- Accession number :
- 31550161
- Full Text :
- https://doi.org/10.1021/acs.jpca.9b07013