2,4,6,8-Tetrachlorodibenzothiophene in the Newark Bay Estuary: The likely source and reaction pathways

Parette, Robert; Pearson, W N

doi:10.1016/j.chemosphere.2014.03.076

Cited by 20 publications

(14 citation statements)

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“…Careful examination of the literature shows that two heterogeneous PCTA/DT formation pathways were proposed: Reactions from elemental carbon, sulfur, and chlorine- and sulfur-containing pesticides [22], and reactions from chemical precursors [23,24,25,26,27], which is the most direct route to the formation of PCTA/DTs. Among different precursors of PCTA/DTs, chlorothiophenols (CTPs) are demonstrated to be the most important precursors of PCTA/DTs, which is consistent with the widely recognized fact that chlorophenols (CPs) are identified to be predominant precursors of PCDD/DFs [23,24,28]. CTPs are used in large quantities in various chemical industries, such as the manufacturing of dyes, insecticides, printing inks, pharmaceuticals, and polyvinyl chloride [29], while CPs are released from direct application as biocides, leaching from wood products, synthesis during bleaching operations, and emissions from operating facilities [30,31].…”

Section: Introductionsupporting

confidence: 73%

Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors

Zuo

Wang

Pan

et al. 2019

IJMS

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Polychlorinated phenoxathiins (PCPTs), polychlorinated dibenzothiophenes (PCDTs), and polychlorinated thianthrenes (PCTAs) are sulfur analogues of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/DFs). Chlorothiophenols (CTPs) and chlorophenols (CPs) are key precursors for the formation of PCTA/PT/DTs, which can react with H or OH to form chloro(thio)phenoxy radical, sulfydryl/hydroxyl-substituted phenyl radicals, and (thio)phenoxyl diradicals. However, previous radical/radical PCTA/DT formation mechanisms in the literature failed to explain the higher concentration of PCDTs than that of PCTAs under the pyrolysis or combustion conditions. In this work, a detailed thermodynamics and kinetic calculations were carried out to investigate the pre-intermediate formation for PCTA/PT/DTs from radical/molecule coupling of the 2-C(T)P with their key radical species. Our study showed that the radical/molecule coupling mechanism explains the gas-phase formation of PCTA/PT/DTs in both thermodynamic and kinetic perspectives. The S/C coupling modes to form thioether-(thio)enol intermediates are preferable over the O/C coupling modes to form ether-(thio)enol intermediates. Thus, although the radical/molecule coupling of chlorophenoxy radical with 2-C(T)P has no effect on the PCDD/PT formation, the radical/molecule coupling of chlorothiophenoxy radical with 2-C(T)P plays an important role in the PCTA/PT formation. Most importantly, the pre-PCDT intermediates formation pathways from the couplings of sulfydryl/hydroxyl-substituted phenyl radical with 2-C(T)P and (thio)phenoxyl diradicals with 2-C(T)P are more favorable than pre-PCTA/PT intermediates formation pathways from the coupling of chlorothiophenoxy radical with 2-C(T)P, which provides reasonable explanation for the high PCDT-to-PCTA ratio in the environment.

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Section: Introductionsupporting

confidence: 73%

Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors

Zuo

Wang

Pan

et al. 2019

IJMS

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“…These are the same positions as in the halogenated carbazoles that have been identified in the environment; therefore this does not allow for the determination of whether halogenation occurred prior to or subsequent to carbazole formation. In contrast, in the case of the contaminant 2,4,6,8-tetrachlorodibenzothiophene (2,4,6,, it was apparent that chlorination occurred prior to formation of the dibenzothiophene structure as chlorination of dibenzothiophene does not preferentially result in 2,4,6,8-TCDT (Parette and Pearson, 2014).…”

Section: Introductionmentioning

confidence: 79%

Halogenated indigo dyes: A likely source of 1,3,6,8-tetrabromocarbazole and some other halogenated carbazoles in the environment

Parette¹,

McCrindle

McMahon³

et al. 2015

Chemosphere

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“…Chlorophenols (CPs) are key precursors in essentially all proposed pathways of the formation of PCDD/Fs [ 13 , 14 , 15 , 16 , 17 , 18 ]. Chlorothiophenols (CTPs) are structurally similar to CPs and have been demonstrated to be the predominant precursors or key intermediates of PCTA/DT formation [ 19 , 20 , 21 ]. CTPs have been widely employed as intermediates in large quantities in various chemical industries, such as in the manufacturing of dyes, insecticides, printing inks, pharmaceuticals and polyvinyl chloride [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

“…Chlorothiophenols (CTPs) are structurally similar to CPs and have been demonstrated to be the predominant precursors or key intermediates of PCTA/DT formation [ 19 , 20 , 21 ]. CTPs have been widely employed as intermediates in large quantities in various chemical industries, such as in the manufacturing of dyes, insecticides, printing inks, pharmaceuticals and polyvinyl chloride [ 19 ]. In particular, the dichlorothiophenols (DCTPs) are used in pharmaceutical industry due to their inhibitory effect on human cytochrome [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol

Shi

et al. 2015

IJMS

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Polychlorinated 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.

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2,4,6,8-Tetrachlorodibenzothiophene in the Newark Bay Estuary: The likely source and reaction pathways

Cited by 20 publications

References 50 publications

Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors

Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors

Halogenated indigo dyes: A likely source of 1,3,6,8-tetrabromocarbazole and some other halogenated carbazoles in the environment

Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol

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