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Low-Temperature Kinetic Isotope Effects in CH3OH + H → CH2OH + H2Shed Light on the Deuteration of Methanol in Space
- Source :
- The Journal of Physical Chemistry - Part A; October 2019, Vol. 123 Issue: 42 p9061-9068, 8p
- Publication Year :
- 2019
-
Abstract
- We calculated reaction rate constants including atom tunneling for the hydrogen abstraction reaction CH3OH + H → CH2OH + H2with 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 CH3group 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 12C/13C kinetic isotope effect is 1.08 at 30 K, while the 16O/18O 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 :
- 10895639 and 15205215
- Volume :
- 123
- Issue :
- 42
- Database :
- Supplemental Index
- Journal :
- The Journal of Physical Chemistry - Part A
- Publication Type :
- Periodical
- Accession number :
- ejs51038265
- Full Text :
- https://doi.org/10.1021/acs.jpca.9b07013