Reaction mechanism and product branching ratios of OH+C2H3F reaction: A theoretical study

Ab initio CCSD(T)/CBS//B3LYP/6-311G(d, p) calculations of the potential energy surface for possible dissociation channels of HOC $_2$ H $_3$ F, as well as Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of rate constants, were carried out, in order to predict statistical product branching ratios in dissociation of HOC $_2$ H $_3$ F at various internal energies. The most favorable reaction pathway leading to the major CH $_2$ CHO+HF products is as the following: OH+C $_2$ H $_3$ F $\rightarrow$ i2 $\rightarrow$ TS14 $\rightarrow$ i6 $\rightarrow$ TS9 $\rightarrow$ i3 $\rightarrow$ TS3 $\rightarrow$ CH $_2$ CHO+HF, where the rate-determining step is HF elimination from the CO bridging position via TS11, lying above the reactants by 3.8 kcal/mol. The CH $_2$ O+CH $_2$ F products can be formed by F atom migration from C $_\beta$ to C $_\alpha$ position via TS14, then H migration from O to C $_\alpha$ position via TS16, and C-C breaking to form the products via TS5, which is 1.8 kcal/mol lower in energy than the reactants, and 4.0 kcal/mol lower than TS11.