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<p>The mechanisms, kinetics and ecotoxicity valuation of the gas-phase CH<sub>2</sub>XO<sub>2</sub> (X = F、Cl、Br and I) with I reactions were investigated by using quantum chemical methods. The calculated results indicate that the title reactions could ocure on either the singlet or triplet potential energy surfaces (PES). Addition/elimination, S<sub>N</sub>2 displacement and H-abstraction mechanisms were found on the singlet PES, and only S<sub>N</sub>2 displacement mechanism was located on the triplet PES. The dominant reaction takes place on the singlet PES, and the primary pathway is CH<sub>2</sub>XO<sub>2</sub> + I → IM1 (CH<sub>2</sub>XOOI) → P1 (CHXO + HIO). Owing to high energy barriers and unstable products, other products generation channels could be neglected. RRKM theory was used to calculate rate constants, and the rate constant at 298&#xa0;K of the CH<sub>2</sub>IO<sub>2</sub> + I reaction is consistent with the experimental data. Time-dependent density functional theory (TDDFT) calaulations revealed that the primary intermediates CH<sub>2</sub>XOOI could undergo photolysis under sunlight. CH<sub>2</sub>XOOI and primary products CHXO (X = F, Cl, Br and I) were regard as toxic substance with potential significant hazards to three aquatic organisms.</p>

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Computational study on the mechanisms and kinetics of the CH2XO2 + I (X = F、Cl、Br and I) reactions in the atmosphere

  • 期刊论文

  • 发表日期：

    2025年1月20日

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  • Jikang Gao,
  • Meilian Zhao,
  • Junchao Liao,
  • Yaru Wang,
  • Yunju Zhang

摘要

The mechanisms, kinetics and ecotoxicity valuation of the gas-phase CH2XO2 (X = F、Cl、Br and I) with I reactions were investigated by using quantum chemical methods. The calculated results indicate that the title reactions could ocure on either the singlet or triplet potential energy surfaces (PES). Addition/elimination, SN2 displacement and H-abstraction mechanisms were found on the singlet PES, and only SN2 displacement mechanism was located on the triplet PES. The dominant reaction takes place on the singlet PES, and the primary pathway is CH2XO2 + I → IM1 (CH2XOOI) → P1 (CHXO + HIO). Owing to high energy barriers and unstable products, other products generation channels could be neglected. RRKM theory was used to calculate rate constants, and the rate constant at 298 K of the CH2IO2 + I reaction is consistent with the experimental data. Time-dependent density functional theory (TDDFT) calaulations revealed that the primary intermediates CH2XOOI could undergo photolysis under sunlight. CH2XOOI and primary products CHXO (X = F, Cl, Br and I) were regard as toxic substance with potential significant hazards to three aquatic organisms.