Atmospheric chemistry of alkyl iodides: theoretical studies on the mechanisms and kinetics of CH3I/C2H5I + NO3reactions

Bai, Feng‐Yang; Wang, Xu; Sun, Yajuan; Pan, Xiumei

doi:10.1039/c5ra16215g

Cited by 13 publications

(12 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As reported in previous studies the photolysis of the compound will take place if the vertical excitation energy is smaller than 4.13 eV or the wavelength is greater than 300 nm. , As shown in Figure and Table S7, it is observed that the absorption wavelength of sulfoxaflor and intermediate complexes is less than 300 nm, indicating photolysis is unlikely in the actinic flux. That is, sulfoxaflor and its derivatives will not photolyze, which is due to the presence of different functional groups in the studied compounds.…”

Section: Resultssupporting

confidence: 60%

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

2021

View full text Add to dashboard Cite

The •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 , H 2 O, HO 2 •, and NO x • (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 × 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.

show abstract

Section: Resultssupporting

confidence: 60%

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

2021

View full text Add to dashboard Cite

show abstract

“…For other intermediate complexes the absorption is very weak. As reported in previous studies, the compounds will undergo photolysis in sunlight only if the vertical excitation energy is smaller than 4.13 eV (∼300 nm). As shown in Figure , the dominant absorption for diuron is 220 nm and is in agreement with the experimental value of 214 nm .…”

Section: Photolysis Of Diuronsupporting

confidence: 57%

Mechanism and Kinetics of Diuron Oxidation Initiated by Hydroxyl Radical: Hydrogen and Chlorine Atom Abstraction Reactions

2019

View full text Add to dashboard Cite

Diuron is a herbicide that has been classified as an environmental pollutant because of its harmful effects on living beings and environment. In the present work, the OH-initiated oxidation reaction of diuron is investigated by performing electronic structure calculations based on density functional theory (DFT) methods, M06-2X, ωB97X-D, and MPWB1K using the 6-31G(d,p) basis set. The CBS-QB3 method is used to validate the results obtained from the DFT methods. All possible initial hydrogen and chlorine atom abstraction reaction pathways involved in the oxidation of diuron were studied, and the favorable reaction pathways were found by analyzing the potential energy surface and thermochemistry of the reactions. The results obtained from the present work show that hydrogen atom abstraction from methyl and amine groups of diuron are energetically favorable, which leads to the formation of diuron radical intermediate and water molecule. The rate constant is calculated for most favorable reaction pathways by using canonical variation transition state theory (CVT) with small curvature tunnelling (SCT) correction over the temperature range 298−1000 K. The atmospheric lifetime of diuron is found to be around 15 days. The subsequent reaction of most favorable diuron radical intermediate with other atmospheric reactive species, such as O 2 , H 2 O, HO 2 , and NO x (x = 1, 2) radicals are studied. The time-dependent DFT calculation is performed to study the photolysis of diuron and favorable diuron radical intermediates. This study provides thermochemical and kinetic data for the oxidation of diuron initiated by OH radical through H atom abstraction reaction.

show abstract

“…However, there are insufficient data to refine these estimates. Possible mechanisms for these reactions are discussed by Bai et al [37].…”

Section: Reactions Of No 3 With Iodidesmentioning

confidence: 99%

“…The data are much more consistent with assuming that the reactions of NO 3 with iodides is initiated by adding or associating with the I group, then reacting further. Theoretical studies of reactions of iodides with NO 3 radicals are discussed by Bai et al [37]. Therefore, for estimation purposes we treat reactions of NO 3 with iodides as additions, with the base rate constant that fits the data included in Table S16 in the SI.…”

Section: Reactions Of No 3 With Iodidesmentioning

confidence: 99%

Estimation of Rate Constants for Reactions of Organic Compounds under Atmospheric Conditions

Carter

2021

Atmosphere

View full text Add to dashboard Cite

Structure–activity (SAR) methods are presented for estimating rate constants at 298 K and approximate temperature dependences for the reactions of organic compounds with OH, NO3, and Cl radicals and O3, and O(3P) in the lower atmosphere. These are needed for detailed mechanisms for the atmospheric reactions of organic compounds. Base rate constants are assigned for the various types of H-abstraction and addition reactions, with correction factors for substituents around the reaction site and in some cases for rings and molecule structure or size. Rate constant estimates are made for hydrocarbons and a wide variety of oxygenates, organic nitrates, amines, and monosubstituted halogen compounds. Rate constants for most hydrocarbons and monofunctional compounds can be estimated to within ±30%, though predictions are not as good for multifunctional compounds, and predictions for ~15% of the rate constants are off by more than a factor of 2. Estimates are more uncertain in the case of NO3 and O3 reactions. The results serve to demonstrate the capabilities and limitations of empirical methods for predicting rate constants for the full variety of organic compounds that may be of interest. Areas where future work is needed are discussed.

show abstract

Atmospheric chemistry of alkyl iodides: theoretical studies on the mechanisms and kinetics of CH₃I/C₂H₅I + NO₃reactions

Abstract: Mechanisms and kinetics of the reactions of the NO3 radical with CH3I and C2H5I have been investigated from a sound theoretical basis.

Cited by 13 publications

References 48 publications

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

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

Mechanism and Kinetics of Diuron Oxidation Initiated by Hydroxyl Radical: Hydrogen and Chlorine Atom Abstraction Reactions

Estimation of Rate Constants for Reactions of Organic Compounds under Atmospheric Conditions

Contact Info

Product

Resources

About