Kinetics of the R+O2 →R-HO plus OH reactions of substituted methyl radicals: Effects of Cl, F, and CF3 substitution and notes on the RO plus O producing channel

Kinetics of ten reactions of substituted methyl radicals producing a carbonyl compound and hydroxy radical were studied computationally using quantum chemistry, transition state theory, and master equation / RRKM. Effects of Cl, F, and CF3 substitution were quantified. Cl substitution results in decreased rate constants. First F sub-stitution decreases the energy barrier and thus increases the rate constants, but second F substitution leaves the energy barrier unchanged and partially reverses the trend in rate constants. CF3 substitution increases the energy barrier and decreases the rate constants. Rate constants of ten R + O2 -> RO + O reactions were also estimated based on detailed balance.

Automated summary

In this study, the kinetics of ten reactions involving substituted methyl radicals producing a carbonyl compound and hydroxy radical were computationally investigated using quantum chemistry, transition state theory, and master equation / RRKM. The effects of Cl, F, and CF3 substitution were quantified. It was found that Cl substitution led to a decrease in rate constants. The first F substitution lowered the energy barrier and subsequently increased the rate constants, while the second F substitution left the energy barrier unchanged and partially reversed the trend in rate constants. CF3 substitution, on the other hand, increased the energy barrier and decreased the rate constants. Additionally, the rate constants of ten R + O2 -> RO + O reactions were estimated based on detailed balance.