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Formation of Chlorotriophenoxy Radicals from Complete Series Reactions of Chlorotriophenols with H and OH Radicals.

Xu F, Shi X, Zhang Q, Wang W - Int J Mol Sci (2015)

Bottom Line: The present study indicates that the structural parameters, thermal data, and rate constants as well as the formation potential of CTPRs from CTPs are strongly dominated by the chlorine substitution at the ortho-position of CTPs.Comparison with the study of formation of chlorophenoxy radicals (CPRs) from chlorophenols (CPs) clearly shows that the thiophenoxyl-hydrogen abstraction from CTPs by H is more efficient than the phenoxyl-hydrogen abstraction from CPs by H, whereas the thiophenoxyl-hydrogen abstraction from CTPs by OH is less impactful than the phenoxyl-hydrogen abstraction from CPs by OH.Reactions of CTPs with H can occur more readily than that of CTPs with OH, which is opposite to the reactivity comparison of CPs with H and OH.

View Article: PubMed Central - PubMed

Affiliation: Environment Research Institute, Shandong University, Jinan 250100, China. xufei@sdu.edu.cn.

ABSTRACT
The chlorothiophenoxy radicals (CTPRs) are key intermediate species in the formation of polychlorinated dibenzothiophenes/thianthrenes (PCDT/TAs). In this work, the formation of CTPRs from the complete series reactions of 19 chlorothiophenol (CTP) congeners with H and OH radicals were investigated theoretically by using the density functional theory (DFT) method. The profiles of the potential energy surface were constructed at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) contribution at 600-1200 K. The present study indicates that the structural parameters, thermal data, and rate constants as well as the formation potential of CTPRs from CTPs are strongly dominated by the chlorine substitution at the ortho-position of CTPs. Comparison with the study of formation of chlorophenoxy radicals (CPRs) from chlorophenols (CPs) clearly shows that the thiophenoxyl-hydrogen abstraction from CTPs by H is more efficient than the phenoxyl-hydrogen abstraction from CPs by H, whereas the thiophenoxyl-hydrogen abstraction from CTPs by OH is less impactful than the phenoxyl-hydrogen abstraction from CPs by OH. Reactions of CTPs with H can occur more readily than that of CTPs with OH, which is opposite to the reactivity comparison of CPs with H and OH.

No MeSH data available.


syn and anti conformers of CTP.
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ijms-16-18714-f001: syn and anti conformers of CTP.

Mentions: Due to the different substitution pattern of thiophenol, chlorothiophenols have 19 congeners, including three monochlorothiophenols (2-CTP, 3-CTP and 4-CTP), six dichlorothiophenols (2,3-DCTP, 2,4-DCTP, 2,5-DCTP, 2,6-DCTP, 3,4-DCTP and 3,5-DCTP), six trichlorothiophenols (2,3,4-TCTP, 2,3,5-TCTP, 2,3,6-TCTP, 2,4,5-TCTP, 2,4,6-TCTP and 3,4,5-TCTP), three tetrachlorothiophenols (2,3,4,5-TeCTP, 2,3,4,6-TeCTP and 2,3,5,6-TeCTP), and pentachlorothiophenols (PCTP). Due to the asymmetric chlorine substitution, there are syn and anti-conformers for 2-CTP, 3-CTP, 2,3-DCTP, 2,4-DCTP, 2,5-DCTP, 3,4-DCTP, 2,3,4-TCTP, 2,3,5-TCTP, 2,3,6-TCTP, 2,4,5-TCTP, 2,3,4,5-TeCTP and 2,3,4,6-TeCTP, respectively. The conformer with the sulfydryl-hydrogen facing the closest neighboring Cl is labeled as the syn-conformer and otherwise the anti-conformer (Figure 1). For a given CTP, the syn-conformer is about 0.5 kcal/mol more stable than the corresponding anti form, suggesting a stabilization effect because of intramolecular hydrogen bonding. So, throughout this paper, CTPs denote the syn-conformers.


Formation of Chlorotriophenoxy Radicals from Complete Series Reactions of Chlorotriophenols with H and OH Radicals.

Xu F, Shi X, Zhang Q, Wang W - Int J Mol Sci (2015)

syn and anti conformers of CTP.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581267&req=5

ijms-16-18714-f001: syn and anti conformers of CTP.
Mentions: Due to the different substitution pattern of thiophenol, chlorothiophenols have 19 congeners, including three monochlorothiophenols (2-CTP, 3-CTP and 4-CTP), six dichlorothiophenols (2,3-DCTP, 2,4-DCTP, 2,5-DCTP, 2,6-DCTP, 3,4-DCTP and 3,5-DCTP), six trichlorothiophenols (2,3,4-TCTP, 2,3,5-TCTP, 2,3,6-TCTP, 2,4,5-TCTP, 2,4,6-TCTP and 3,4,5-TCTP), three tetrachlorothiophenols (2,3,4,5-TeCTP, 2,3,4,6-TeCTP and 2,3,5,6-TeCTP), and pentachlorothiophenols (PCTP). Due to the asymmetric chlorine substitution, there are syn and anti-conformers for 2-CTP, 3-CTP, 2,3-DCTP, 2,4-DCTP, 2,5-DCTP, 3,4-DCTP, 2,3,4-TCTP, 2,3,5-TCTP, 2,3,6-TCTP, 2,4,5-TCTP, 2,3,4,5-TeCTP and 2,3,4,6-TeCTP, respectively. The conformer with the sulfydryl-hydrogen facing the closest neighboring Cl is labeled as the syn-conformer and otherwise the anti-conformer (Figure 1). For a given CTP, the syn-conformer is about 0.5 kcal/mol more stable than the corresponding anti form, suggesting a stabilization effect because of intramolecular hydrogen bonding. So, throughout this paper, CTPs denote the syn-conformers.

Bottom Line: The present study indicates that the structural parameters, thermal data, and rate constants as well as the formation potential of CTPRs from CTPs are strongly dominated by the chlorine substitution at the ortho-position of CTPs.Comparison with the study of formation of chlorophenoxy radicals (CPRs) from chlorophenols (CPs) clearly shows that the thiophenoxyl-hydrogen abstraction from CTPs by H is more efficient than the phenoxyl-hydrogen abstraction from CPs by H, whereas the thiophenoxyl-hydrogen abstraction from CTPs by OH is less impactful than the phenoxyl-hydrogen abstraction from CPs by OH.Reactions of CTPs with H can occur more readily than that of CTPs with OH, which is opposite to the reactivity comparison of CPs with H and OH.

View Article: PubMed Central - PubMed

Affiliation: Environment Research Institute, Shandong University, Jinan 250100, China. xufei@sdu.edu.cn.

ABSTRACT
The chlorothiophenoxy radicals (CTPRs) are key intermediate species in the formation of polychlorinated dibenzothiophenes/thianthrenes (PCDT/TAs). In this work, the formation of CTPRs from the complete series reactions of 19 chlorothiophenol (CTP) congeners with H and OH radicals were investigated theoretically by using the density functional theory (DFT) method. The profiles of the potential energy surface were constructed at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) contribution at 600-1200 K. The present study indicates that the structural parameters, thermal data, and rate constants as well as the formation potential of CTPRs from CTPs are strongly dominated by the chlorine substitution at the ortho-position of CTPs. Comparison with the study of formation of chlorophenoxy radicals (CPRs) from chlorophenols (CPs) clearly shows that the thiophenoxyl-hydrogen abstraction from CTPs by H is more efficient than the phenoxyl-hydrogen abstraction from CPs by H, whereas the thiophenoxyl-hydrogen abstraction from CTPs by OH is less impactful than the phenoxyl-hydrogen abstraction from CPs by OH. Reactions of CTPs with H can occur more readily than that of CTPs with OH, which is opposite to the reactivity comparison of CPs with H and OH.

No MeSH data available.