A Computational Study on the Atmospheric Oxidation of CF3OCHFCF3 (HFE-227) Initiated by ˙OH radical: Mechanism, Kinetics, Degradation of Product Radicals and Ecotoxicity

Abstract

In the present work, we have carried out ˙OH radical-initiated oxidation of CF3OCHFCF3 by considering H-abstraction reaction and ˙OH-addition reaction to the C-atom of CF3OCHFCF3 with simultaneous C-C and C-O bond-breaking. The energies of all the species involved in the title reaction are calculated using the M06-2X functional with the 6-311+G(d,p) basis set, and these energies are further refined using the coupled-cluster CCSD(T) method with the same basis set. The energy profile diagram and thermochemistry results indicate that the H-atom abstraction reaction pathway is energetically more favourable and thermodynamically more dominant than the OH-addition reactions with simultaneous C-C and C-O bond breaking. The rate constant analysis also indicates that the H-abstraction reaction is more favourable than ˙OH-addition reactions. At 298.15 K and 1 atm., the estimated overall rate constant for this reaction is found to be 1.16×10-15 cm3 molecules-1s-1, which is in good agreement with previously reported results. Further, the atmospheric lifetime, radiative efficiency, global warming potentials, and photochemical ozone creation potential of the title molecule are also reported herein. Moreover, the degradation of the ˙OCHFCF3, CF3OC˙FCF3, and CF3O(C˙)FH product radicals are also explored, and it is found that HFCO, ˙CF3, CF3O˙, COFCF3, and COFCF3 are formed as end products. Finally, photolytic characterisation of reactant, intermediates, and products are analysed, and their ecotoxicities are reported.