Mechanism, kinetics, and environmental assessment of OH‐initiated transformation of CTDE in the atmosphere

The transformation mechanism and kinetics of 2‐chloro‐1,1,2‐trifluoroethyl‐difluoromethyl‐ether (CTDE, CHF2OCF2CHFCl) triggered by OH radicals are studied by density‐functional theory methods and canonical variational transition state theory. The computational rate constant including small‐curvature...

Full description

Saved in:
Bibliographic Details
Published in:International journal of quantum chemistry 2020-08, Vol.120 (15), p.n/a
Main Authors: Yang, Yu‐Qi, Zhang, Wei, Deng, Ming‐Shuai, Pan, Xiu‐Mei, Bai, Feng‐Yang, Tan, Lei
Format: Article
Language:English
Subjects:
Chemistry
Chlorofluorocarbons
computational chemistry
Dechlorination
Environmental assessment
Greenhouse effect
haloethers
Kinetics
Ozone depletion
Physical chemistry
Quantum physics
Radiative forcing
Radicals
reaction mechanism
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The transformation mechanism and kinetics of 2‐chloro‐1,1,2‐trifluoroethyl‐difluoromethyl‐ether (CTDE, CHF2OCF2CHFCl) triggered by OH radicals are studied by density‐functional theory methods and canonical variational transition state theory. The computational rate constant including small‐curvature tunneling correction is found to be in commendable agreement with the experimental data. Two hydrogen ion channels to form the alkyl radicals of C·F2OCF2CHFCl and CHF2OCF2C·FCl are observed, and the formation of CHF2OCF2C·FCl is found to be more favorable than C·F2OCF2CHFCl kinetically and thermodynamically. Subsequent evolution of CHF2OCF2C·FCl in the presence of NO and O2 indicates that the organic nitrate (CHF2OCF2CONO2FCl) is the stable product. The dechlorinate of alkoxy radical (CHF2OCF2C(O·)FCl) is the most favorable degradation channel, and the estimated ozone depletion potential for CTDE relative to chlorofluorocarbon‐11 is 0.0204, which could lead to ozone depletion as a consequence. The computed atmospheric lifetime for CTDE is found to be 3.69 years by considering the combined contributions from OH radicals and Cl atoms. The total radiative forcing and global warming potential of CTDE are, respectively, 0.547 W m−2 ppbv and 628.58 (100 years) at 298 K, suggesting that the contribution of CTDE to the greenhouse effect is moderate. The subsequent reaction pathways of IM1 in the NO‐rich environments.
ISSN:0020-7608
1097-461X
DOI:10.1002/qua.26250