The atmospheric degradation pathways of BrCH2O2: computational calculation on mechanisms of the reaction with HO2

Mechanisms for the atmospheric degradation reaction of BrCH2O2 + HO2 were investigated using quantum chemistry methods. The result indicates that the dominant product is BrCH2OOH + O2(3Σ). While CH2O + HBr + O3, BrCHO + OH + HO2 and CH2O + Br + HO3 will be competitive to a certain extent in the atmosphere. Meanwhile, the nascent product – BrCH2OOH reacts easily with OH radicals leading to BrCH2O2 again under the atmospheric conditions. Moreover, OH radicals could act as a catalyst in the net reaction of BrCH2OOH → BrCHO + H2O. Thus the proposed product BrCHO + H2O + O2 in the experiment might be generated from the subsequent reaction of BrCH2OOH with extra OH radicals. Comparisons indicate that halogen substitution effect makes minor contributions to the XCH2O2 (X = H, F, Cl and Br) + HO2 reactions in the atmosphere.