A mechanistic study of the decomposition and reactivity of the C 4 F 9 OC 2 H 4 O• radical derived from HFE-7200 between 200 and 400 K

Abstract

The mechanism of decomposition and reactivity of C₄F₉OC₂H₄O• radical obtained from C₄F₉OC₂H₅ (HFE-7200) was studied by a computational method. All calculations were performed at the B3LYP and mPW1PW91 levels of theory with a 6-311G(d,p) basis set. Four possible pathways were investigated: (i) reaction with atmospheric O₂, (ii) reaction with atmospheric OH radical, (iii) release of H radical and (iv) rearrangement of the radical in two steps and then C–O bond cleavage. These pathways (1), (2), (3), (4a), (4b) and (4c) for the four steps listed, respectively, had energy barriers equal to 6.9, 11.9, 17.7, 30.8, 11.0 and 9.9 kcal mol^–1, respectively. Canonical transition state theory was used to calculate rate constants for all steps in the range of 200–400 K and Arrhenius diagrams were plotted for them. The results showed that reaction with atmospheric O₂ with a rate constant equal to 48.97 cm³ mol^–1 s^–1 is the dominant pathway for degradation of C₄F₉OC₂H₄O• radical in the atmosphere.