Theoretical investigation on degradation of CHCCH2OH by NO3 radicals in the atmosphere

Abstract

A detailed computational investigation is executed on the reaction between NO₃ and CHCCH₂OH at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) level. Addition/elimination and H-abstraction mechanisms are found for the NO₃ + CHCCH₂OH reaction, and they could compete with each other. The most feasible addition/elimination pathway through a series of central-C addition, 1,4-H migration to generate intermediates IM1 (CHCONO₂CH₂OH) and IM3 (CH₂CONO₂CH₂O), and then IM3 directly decompose into product P2 (CH₂CONO₂CHO + H). The dominant H-abstraction pathway is abstracting the H atom of the –CH₂– group to generate h-P1 (CHCCHOH + HNO₃). RRKM-TST theory was used to compute the kinetics and product branching ratios of the NO₃ + CHCCH₂OH reaction at 200–3000 K. The rate constants at 298 K are consistent with the experimental values. The lifetime of CHCCH₂OH is estimated to be 59.72 days at 298 K. The implicit solvent model was used to examine the solvent effect on the total reaction. Based on the quantitative structure–activity relationship (QSAR) model, the toxicity during the degradation process is increased towards fish, and decreased towards daphnia and green algae.