Estimation of rate coefficients and branching ratios for reactions of organic peroxy radicals for use in automated mechanism construction

摘要

Organic peroxy radicals (RO_2), formed from the degradation of hydrocarbons and other volatile organic compounds (VOCs), play a key role in tropospheric oxidation mechanisms. Several competing reactions may be available for a given RO_2 radical, the relative rates of which depend on both the structure of RO_2 and the ambient conditions. Published kinetics and branching ratio data are reviewed for the bimolecular reactions of RO_2 with NO, NO_2, NO_3, OH and HO_2; and for their self-reactions and cross-reactions with other RO_2 radicals. This information is used to define generic rate coefficients and structure–activity relationship (SAR) methods that can be applied to the bimolecular reactions of a series of important classes of hydrocarbon and oxygenated RO_2 radicals. Information for selected unimolecular isomerization reactions (i.e. H-atom shift and ring-closure reactions) is also summarized and discussed. The methods presented here are intended to guide the representation of RO_2 radical chemistry in the next generation of explicit detailed chemical mechanisms.