Partially fluorinated alcohols are better alternatives to Chloro-fluorocarbons and Hydro-chlorofluorocarbons as they are non-ozone depleting compounds. They might, however, play a possible role as greenhouse gases owing to the presence of C–F bond that can have absorption features in the IR region. Thus, understanding their atmospheric implication is a cause of concern. Quantum chemical calculations on the gas-phase H-abstraction reactions of CH2FCH2OH with OH radicals were performed using the CCSD(T)/M06-2X/aug-cc-pVTZ method. Conformational analysis shows that the gauche conformer is the lowest in energy and hence, the only conformer considered for the study. The rate coefficients were estimated using the VTST-ISPE method incorporating small curvature tunnelling correction and the calculated rate coefficient k = 6.73×10-13 cm3molecule-1s-1at 298K is in close agreement with the reported experimental result. The temperature variation of the rate in the range 230-1000K is best described by the three-parameter equation. The Atmospheric lifetime was estimated assuming that CH2FCH2OH removal from the atmosphere occurs only through OH and Cl initiated reactions and was calculated to be 20.57 and 2.89 days at global average concentration and at Marine Boundary layer concentration of Cl atoms, respectively. The Global Warming Potential at 20-, 100- and 500-years time horizons are estimated to be 18.5, 6.4, and 1.7 respectively. It can be stated that CH2FCH2OH is a short-lived gas, less harmful to the environment, and can be used commercially. Further, atmospheric degradation processes of CH2FCHOH radical through several competing reaction channels have been elaborated. Thermochemical parameters of Gibbs free energies for all plausible degradation channels were calculated and these data were useful to find the feasibility of different degradation channels. Rate coefficient values of the primary oxidation products were reported for the first time. Regeneration of hydroxyl radical (OH) from the degradation reaction and the ozone formation potential in the troposphere are also deliberated.

Theoretical studies on atmospheric reaction of CH2FCH2OH with OH radical and fate of CH2FCHOH radical

ACS Spring 2022

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