The mechanism and dynamic studies for the reactions of OH radical with CH3−nFnOCF2CHFCl (n = 0, 1, and 2)

•The mechanisms of CH3−nFnOCF2CHFCl (n = 0, 1, and 2) with OH radical are studied theoretically.•The effect of fluorine substitution on the reactivity is explored.•The total rate constants will decrease with the increasing of the fluorine atoms.

The mechanism and dynamic properties for the multi-channel reactions of CH3OCF2CHFCl + OH (R1), CH2FOCF2CHFCl + OH (R2), and CHF2OCF2CHFCl + OH (R3) were carried out theoretically. The geometric parameters were optimized at the BMK/6-311+G(d,p) level. Subsequently, the energies were refined at the BMC-CCSD level. Based on the information of partial potential energy surface, the rate constants were evaluated by using the canonical variational transition state theory (CVT) with a small-curvature tunneling correction (SCT) method. For every reaction, there are two possible H-abstraction positions, i.e., CH3−nFn (n = 0, 1, and 2) group and CHFCl group. The major reaction channel and the effect of fluorine substitution on the reactivity are explored. Both questions are elucidated by analyzing the reaction energy, barrier height, bond dissociation energy, and rate constants.

Graphical abstractBy using dual-level direct dynamics method (X//Y), schematic pathways and rate constants for the reaction CH3−nFnOCF2CHFCl (n = 0, 1, and 2) + OH are obtained. The predominant reaction pathway is hydrogen abstraction rather than displacement process because of higher barrier.Figure optionsDownload full-size imageDownload as PowerPoint slide