Chem. J. Chinese Universities ›› 2022, Vol. 43 ›› Issue (10): 20220271.doi: 10.7503/cjcu20220271

• Physical Chemistry • Previous Articles     Next Articles

Theoretical Study on the Fragmentation Mechanism of CH3SSCH3 Radical Cation Initiated by OH Radical

CHENG Yuanyuan1(), XI Biying2   

  1. 1.Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation
    2.School of Chemistry,Biology and Material Science,East China University of Technology,Nanchang 330013,China
  • Received:2022-04-24 Online:2022-10-10 Published:2022-06-13
  • Contact: CHENG Yuanyuan E-mail:cyy@ecut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22103011);the Research Fund of East China University of Technology, China(DHBK2018065)

Abstract:

The fragmentation mechanism of CH3SSCH3 radical cation(CH3SSCH3?+, DMDS?+) initiated by OH radical(·OH) in the gas phase, toluene, and water was studied at the UωB97X-D/6-311+G** level. The influence of solvent effect on the reaction was discussed. The results show that DMDS·+ firstly reacts with ·OH to form the radical coupling product CH3S(OH)SCH3+(R1) or the hydrogen abstraction product complex[CH2=SSCH3+H2O]+(R2). Then, cleavage of S—S bond concerted proton transfer directly occurs for the fragmentation of R1. While, conformational change, carbophilic addition to C=S double bond and cleavage of S—S bond concerted proton transfer occur in turn for the fragmentation of R2. Deprotonated products are CH3SOH, CH2=S, and HSCH2OH. Toluene slightly reduces the free energy barrier of the rate determining step in the fragmentation reaction. Water solvent is favorable for the fragmentation of R1, but unfavorable for the fragmentation of R2, especially an explicit water molecule participates in the reaction. In the gas phase, toluene, and water, with ·OH and DMDS·+ as initial reactant, although the free energy barriers of the rate determining steps are 167.6—202.8 kJ/mol, the fragmentation reactions are all exothermice reactions(?154.3— ?31.4 kJ/mol).

Key words: OH Radical, CH3SSCH3 Radical cation, Fragmentation, Reaction mechanism, Density functional theory

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