Computational investigation on NO3-initiated degradation of p,p′-DDE in atmosphere: Mechanism and kinetics

Li, Yunfeng; Shi, Xiangli; He, Maoxia

doi:10.1016/j.comptc.2015.06.003

Cited by 1 publication

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References 39 publications

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“…The subsequent reactions include five elementary reactions: the O 2 addition to form the bicyclic peroxy radicals, the addition with NO, the cleavage of the O–ONO bond, the synchronous C (1) –C (2) and O–O bonds cleavage to form ring-opening radicals, and the barrierless C (3) –C (4) bond cleavage to form dialdehyde P2 and alcohol ketone P3. The alternative reaction of the peroxy radicals IM18a/s is expected to react with NO in the atmosphere. − The radicals IM18a/s can associate with NO to generate alkoxy radicals and epoxides by eliminating NO 2 molecules. As the third major component of the atmosphere, water molecules are also possibly involved in the subsequent reactions. , However, the high potential barriers (19.55–20.32 kcal mol –1 ) imply the reactions of alkoxy radicals with H 2 O molecules are inhibited energetically.…”

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confidence: 99%

Theoretical and Kinetic Properties of OH Radical-Initiated Oxidation of Galaxolide in the Atmosphere

Sun

Zhang

2018

J. Phys. Chem. A

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Galaxolide (HHCB), an important emerging contaminant, has attracted great environmental concern owing to its widespread occurrence and potential toxicity. In this study, the detailed multichannel mechanism of OH radical-initiated atmospheric degradation reactions of HHCB has been investigated by employing density functional theory (DFT). The reactants, transition states, intermediates, and products were optimized at the MPWB1K/6-31+G(d,p) level, and single-point energies were further refined at the MPWB1K/6-311+G(3df,2p) level of theory. The canonical variational transition-state (CVT) theory combined with the small curvature tunneling (SCT) was performed to evaluate the Arrhenius expressions and rate constants of key elementary reactions over a suitable range of 180−370 K. The thermodynamic and kinetic calculation results show that OH addition and hydrogen abstraction reactions are competitive pathways for HHCB. The dominant products in the presence of O 2 /NO are epoxide, dialdehyde, alcohol ketone, cyclolactone compounds, and HO 2 radicals. At 298 K, the total rate constant of OH-initiated degradation of HHCB is 2.71 × 10 −11 cm 3 molecule −1 s −1 . The atmospheric lifetime of HHCB determined by OH-initiated reactions is 10.09 h, which is in favor of the phenomenon of medium-range transport for HHCB in the atmosphere.

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