Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol
AbstractPolychlorinated thianthrene/dibenzothiophenes (PCTA/DTs) are sulfur analogues compounds to polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs). Chlorothiophenols (CTPs) are key precursors to form PCTA/DTs. 2,4-DCTP has the minimum number of Cl atoms to form 2,4,6,8-tetrachlorinated dibenzothiophenes (2,4,6,8-TeCDT), which is the most important and widely detected of the PCDTs. In this paper, quantum chemical calculations were carried out to investigate the homogeneous gas-phase formation of PCTA/DTs from 2,4-DCTP and 2,4,6-TCTP precursors at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. Several energetically feasible pathways were revealed to compare the formation potential of PCTA/DT products. The rate constants of the crucial elementary reactions were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) correction over a wide temperature range of 600–1200 K. This study shows that pathways that ended with elimination of Cl step were dominant over pathways ended with elimination of the H step. The water molecule has a negative catalytic effect on the H-shift step and hinders the formation of PCDTs from 2,4-DCTP. This study, together with works already published from our group, clearly illustrates an increased propensity for the dioxin formation from CTPs over the analogous CPs. View Full-Text
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Xu, F.; Shi, X.; Li, Y.; Zhang, Q. Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol. Int. J. Mol. Sci. 2015, 16, 20449-20467.
Xu F, Shi X, Li Y, Zhang Q. Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol. International Journal of Molecular Sciences. 2015; 16(9):20449-20467.Chicago/Turabian Style
Xu, Fei; Shi, Xiangli; Li, Yunfeng; Zhang, Qingzhu. 2015. "Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol." Int. J. Mol. Sci. 16, no. 9: 20449-20467.