American Chemical Society
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Impact of the Water Molecule on the Gas-Phase Reaction between Acetone and Cl Atoms

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journal contribution
posted on 2021-04-02, 16:35 authored by Cici Fan, Weigang Wang, Bo Shi, Ke Wang, Yan Chen, Zheng Sun, Maofa Ge
The role of the water molecule in the atmospheric reaction between CH3COCH3 and Cl atoms was investigated at the theoretical level of CCSD­(T)/aug-cc-pVTZ//BHandHLYP/aug-cc-pVDZ. The reaction between acetone and Cl atoms proceeds through three paths: an H-abstraction reaction, a −CH3 abstraction reaction, and an addition/elimination reaction by Cl, leading to the formation of CH3COCH2 + HCl (+H2O), CH3CO + CH3Cl (+H2O), and CH3COCl + CH3 (+H2O), respectively. The formation pathway of CH3COCH2 + HCl in the three paths occupies a dominant position, with a rate constant of 1.08 × 10–12 cm3 molecule–1 s–1. However, water-assisted CH3COCH3 + Cl reactions become more complex, proceeding through 10 different paths. At 298 K, the effective rate constant for CH3COCH2 + HCl + H2O formation is 8.46 × 10–15 cm3 molecule–1 s–1, and the effective rate constant decreases by 3–4 orders of magnitudes in the temperature range of 216.69–298.15 K. Therefore, it is concluded that water exerts a hindering effect on the CH3COCH3 + Cl + H2O reaction under atmospheric conditions, but it is not enough to change the dominant position of the CH3COCH3 + Cl reaction under anhydrous conditions.