Estimation of n‐octanol/water Partition Coefficients (Kow) of all PCB Congeners by Ab initio and a Cl Substitution Position Method

Han, Xiaobing; Wang, Zunyao; Zhai, Zhicai; Wang, Liansheng

doi:10.1002/qsar.200530141

Cited by 32 publications

(20 citation statements)

References 15 publications

(12 reference statements)

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“…The optimal structure was obtained using DFT at the B3LYP/6-31G*level. This method has yielded satisfying results in previous research [24, 25]. The vibrational frequencies were calculated at the same level, and showed that the transition state has only one imaginary frequency, and the intermediate for each transition state has no imaginary frequency.…”

Section: Methodssupporting

confidence: 56%

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect

Xin

Yang

Liu

2017

Chemistry Central Journal

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The reaction pathways of PCB-77 in the atmosphere with ·OH, O2, NOx, and 1O2 were inferred based on density functional theory calculations with the 6-31G* basis set. The structures the reactants, transition states, intermediates, and products were optimized. The energy barriers and reaction heats were obtained to determine the energetically favorable reaction pathways. To study the solvation effect, the energy barriers and reaction rates for PCB-77 with different polar and nonpolar solvents (cyclohexane, benzene, carbon tetrachloride, chloroform, acetone, dichloromethane, ethanol, methanol, acetonitrile, dimethylsulfoxide, and water) were calculated. The results showed that ·OH preferentially added to the C5 atom of PCB-77, which has no Cl atom substituent, to generate the intermediate IM5. This intermediate subsequently reacted with O2 via pathway A to generate IM5a, with an energy barrier of 7.27 kcal/mol and total reaction rate of 8.45 × 10−8 cm3/molecule s. Pathway B involved direct dehydrogenation of IM5 to produce the OH-PCBs intermediate IM5b, with an energy barrier of 28.49 kcal/mol and total reaction rate of 1.15 × 10−5 cm3/molecule s. The most likely degradation pathway of PCB-77 in the atmosphere is pathway A to produce IM5a. The solvation effect results showed that cyclohexane, carbon tetrachloride, and benzene could reduce the reaction energy barrier of pathway A. Among these solvents, the solvation effect of benzene was the largest, and could reduce the total reaction energy barrier by 25%. Cyclohexane, carbon tetrachloride, benzene, dichloromethane, acetone, and ethanol could increase the total reaction rate of pathway A. The increase in the reaction rate of pathway A with benzene was 8%. The effect of solvents on oxidative degradation of PCB-77 in the atmosphere is important.Graphical abstractThe reaction pathways of PCB-77 in the atmosphere with •OH, O2, NOx, and 1O2 were inferred based on density functional theory calculations with the 6-31G* basis set. Different polar and nonpolar solvents: cyclohexane, benzene, carbon tetrachloride, chloroform, acetone, dichloromethane, ethanol, methanol, acetonitrile, dimethylsulfoxide, and water were selected to study the solvation effect on the favorable reaction pathways. The investigated results showed what kind of pathway was most likely to occur and the solvent effect on the reaction pathway

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Section: Methodssupporting

confidence: 56%

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect

Xin

Yang

Liu

2017

Chemistry Central Journal

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“…The HQSAR contribution maps reveal that the Cl substitution position is important, this is because the change of substitution pattern will result in the change of the dispersive force and polarizability of PCBs. Usually molecules with large polarizability are easy to enter octanol phase, therefore, resulting in relatively high log K OW value (Han et al, 2006).…”

Section: Hqsar Models For Log K Owmentioning

confidence: 99%

QSPR models for predicting generator-column-derived octanol/water and octanol/air partition coefficients of polychlorinated biphenyls

Yuan

Zhang

et al. 2016

Ecotoxicology and Environmental Safety

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Octanol/water (K(OW)) and octanol/air (K(OA)) partition coefficients are two important physicochemical properties of organic substances. In current practice, K(OW) and K(OA) values of some polychlorinated biphenyls (PCBs) are measured using generator column method. Quantitative structure-property relationship (QSPR) models can serve as a valuable alternative method of replacing or reducing experimental steps in the determination of K(OW) and K(OA). In this paper, two different methods, i.e., multiple linear regression based on dragon descriptors and hologram quantitative structure-activity relationship, were used to predict generator-column-derived log K(OW) and log K(OA) values of PCBs. The predictive ability of the developed models was validated using a test set, and the performances of all generated models were compared with those of three previously reported models. All results indicated that the proposed models were robust and satisfactory and can thus be used as alternative models for the rapid assessment of the K(OW) and K(OA) of PCBs.

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“…Uncertainty in saline water H values for OCPs was b12% (Cetin et al, 2006). Salting-out constants (K s , L mol − 1 ) for PCBs that were calculated with the method by Ni and Yalkowsky (2003) using their octanol-water partition coefficients (Han et al, 2006) ranged between 0.341 (PCB-31) and 0.402 (PCB-180). H ⁎ , the Henry's law constant in saline water was calculated using [log (H ⁎ / H) = K s C s ] where C s is the molar concentration of salt solution (measured as 0.51 and 0.62 M for winter and summer samples, respectively).…”

Section: Air-water Exchangementioning

confidence: 99%

Air–water exchange of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) at a coastal site in Izmir Bay, Turkey

et al. 2008

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The air-water exchange of polychlorinated biphenyl (PCB) and organochlorine pesticides (OCPs) were investigated using paired air-water samples (n = 16) collected in July and February-March, 2005 from Guzelyali Port in Izmir Bay, Turkey. Atmospheric PCBs and OCPs were mainly in gas-phase in both periods. However, their dissolved and particle-phase water concentrations were comparable. For PCBs, 3 and 4-Cl congeners were dominant while chlorpyrifos, endosulfans and HCHs were the most abundant OCPs for all samples. Especially in summer, calculated net gas-exchange PCB fluxes were mainly volatilization from the water ranging from − 0.2 (volatilization, PCB-101) to −30.0 (volatilization, PCB-31) ng m − 2 day − 1 . For OCPs, net flux ranged from −0.03 (volatilization, cis-nonachlor) to 1568 (deposition, endosulfan I) ng m − 2 day − 1 and they have seasonal variations with generally deposition in winter and volatilization in summer. However, endosulfan I, II, endosulfan sulfate, α-and γ-HCH deposited in both periods. The calculated residence times of PCBs and OCPs in the water column indicated that the gasexchange in the Bay is at least as or a more important mechanism than advection. Annual gaseous absorption and volatilization fluxes were calculated and were used along with the estimated dry deposition fluxes and wet deposition fluxes measured recently at a suburban site in Izmir to determine the relative contributions of different atmospheric mechanisms to the pollutant inventory of the Bay water column. Results suggested that the relative contributions of all studied mechanisms to the water column PCB and OCP inventories were significant.

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Estimation of n‐octanol/water Partition Coefficients (K_ow) of all PCB Congeners by Ab initio and a Cl Substitution Position Method

Cited by 32 publications

References 15 publications

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect

QSPR models for predicting generator-column-derived octanol/water and octanol/air partition coefficients of polychlorinated biphenyls

Air–water exchange of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) at a coastal site in Izmir Bay, Turkey

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