Mechanism, Kinetics, and Ecotoxicity Assessment of •OH-Initiated Oxidation Reactions of Sulfoxaflor

The center dot OH-initiated reaction mechanism and kinetics of sulfoxaflor were investigated by using electronic structure calculations. The possible hydrogen atom and cyano group abstraction reaction pathways were studied, and the calculated thermochemical parameters show that the hydrogen atom abstraction from the C7 carbon atom is the more favorable reaction pathway. The subsequent reactions for the favorable intermediate (I4) with other atmospheric reactive species, such as O-2, H2O, HO2 center dot, and NOx center dot (x = 1, 2), were studied in detail. The products identified from the subsequent reactions could contribute to secondary organic aerosol (SOA) formation in the atmosphere. The intermediates and products formed from the initial and subsequent reactions are equally as toxic as the parent sulfoxaflor. At 298 K, the rate constant calculated for the formation of the favorable intermediate I4 is 2.54 x 10(-12) cm(3) molecule(-1) s(-1), which shows that the lifetime of sulfoxaflor is 54 h. The excited-state calculation performed through time-dependent density functional theory shows that the photolysis of the title molecule is unlikely in the atmosphere. The global warming potentials (GWPs) for different time horizons, photochemical ozone creation potential (POCP), and ecotoxicity analysis were also studied for the insecticide sulfoxaflor.

Automated summary

The reaction mechanism and kinetics of sulfoxaflor initiated by the center dot OH were investigated using electronic structure calculations. It was found that hydrogen atom abstraction from the C7 carbon atom is the more favorable reaction pathway. The subsequent reactions of sulfoxaflor with other atmospheric reactive species were studied in detail, with the products identified potentially contributing to secondary organic aerosol (SOA) formation in the atmosphere.