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Aydogdu S, Hatipoglu A. Theoretical insights into the reaction mechanism and kinetics of ampicillin degradation with hydroxyl radical. J Mol Model 2023; 29:63. [PMID: 36738349 DOI: 10.1007/s00894-023-05462-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023]
Abstract
CONTEXT Ampicillin (AMP) is a penicillin-class beta-lactam antibiotic widely used to treat infections caused by bacteria. Therefore, due to its widespread use, this antibiotic is found in wastewater, and it contains long-term risks such as toxicity to all living organisms. METHOD In this study, the degradation reaction of ampicillin with hydroxyl radical was investigated by the density functional theory (DFT) method. All the calculations were performed with B3LYP functional at 6-31G(d,p) basis set. RESULTS The thermodynamic energy values and reaction rates of all possible reaction paths were calculated. The addition of the hydroxyl radical to the carbonyl group of the beta-lactam ring is thermodynamically the most probable reaction path. The calculated overall reaction rate constant is 1.36 × 1011 M-1 s-1. To determine the effect of temperature on the reaction rate, rate constants were calculated for all reaction paths at five different temperatures. The subsequent reaction kinetics of the most preferred primary route was also examined, and the toxicity values of the intermediates were estimated. The acute toxicity of AMP and its degradation product were calculated using the Ecological Structure Activity Relationships (ECOSAR) software. The degradation product was found to be more toxic than AMP.
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Affiliation(s)
- Seyda Aydogdu
- Department of Chemistry, Yildiz Technical University, 34220, Istanbul, Turkey
| | - Arzu Hatipoglu
- Department of Chemistry, Yildiz Technical University, 34220, Istanbul, Turkey.
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2
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Adeniyi AA, Adeniyi JN, Olumayede EG. The theoretical study of the oxidation reaction of hydroxyl radical for the removal of volatile organic aliphatic and aromatic aldehydes from the atmosphere. Struct Chem 2023. [DOI: 10.1007/s11224-022-02120-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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3
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Xing L, Meng Q, Zhang L. A thorough theoretical mechanistic study of OH-initiated oxidative degradation mechanism for large polycyclic aromatic hydrocarbons. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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4
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Wu X, Huang C, Niu S, Zhang F. New theoretical insights into the reaction kinetics of toluene and hydroxyl radicals. Phys Chem Chem Phys 2020; 22:22279-22288. [DOI: 10.1039/d0cp02984j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work provides theoretical insights into the kinetics of toluene + OH, focusing on the anharmonic effect and the accuracy of barrier heights.
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Affiliation(s)
- Xiaoqing Wu
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
- Hefei National Laboratory for Physical Sciences at the Microscale
| | - Can Huang
- Chair of Technical Thermodynamics
- RWTH Aachen University
- 52062 Aachen
- Germany
| | - Shiyao Niu
- Science and Technology on Combustion and Explosion Laboratory
- Xi'an Modern Chemistry Research Institute
- Xi'an
- P. R. China
- School of Chemistry and Materials Science
| | - Feng Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale
- University of Science and Technology of China
- Hefei
- P. R. China
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5
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Wang S, Wang Z. Elucidating Direct Photolysis Mechanisms of Different Dissociation Species of Norfloxacin in Water and Mg 2+ Effects by Quantum Chemical Calculations. Molecules 2017; 22:molecules22111949. [PMID: 29137112 PMCID: PMC6150356 DOI: 10.3390/molecules22111949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 11/03/2017] [Accepted: 11/08/2017] [Indexed: 11/29/2022] Open
Abstract
The study of pollution due to combined antibiotics and metals is urgently needed. Photochemical processes are an important transformation pathway for antibiotics in the environment. The mechanisms underlying the effects of metal-ion complexation on the aquatic photochemical transformation of antibiotics in different dissociation forms are crucial problems in science, and beg solutions. Herein, we investigated the mechanisms of direct photolysis of norfloxacin (NOR) in different dissociation forms in water and metal ion Mg2+ effects using quantum chemical calculations. Results show that different dissociation forms of NOR had different maximum electronic absorbance wavelengths (NOR2+ < NOR0 < NOR+) and showed different photolysis reactivity. Analysis of transition states (TS) and reaction activation energies (Ea) indicated NOR+ generally underwent loss of the piperazine ring (C10–N13 bond cleavage) and damage to piperazine ring (N13–C14 bond cleavage). For NOR2+, the main direct photolysis pathways were de-ethylation (N7–C8 bond cleavage) and decarboxylation (C2–C5 bond cleavage). Furthermore, the presence of Mg2+ changed the order of the wavelength at maximum electronic absorbance (NOR+-Mg2+ < NOR0-Mg2+ < NOR2+-Mg2+) and increased the intensities of absorbance peaks of all three dissociation species of NOR, implying that Mg2+ played an important role in the direct photolysis of NOR0, NOR+, and NOR2+. The calculated TS results indicated that the presence of Mg2+ increased Ea for most direct photolysis pathways of NOR, while it decreased Ea for some direct photolysis pathways such as the loss of the piperazine ring and the damage of the piperazine ring of NOR0 and the defluorination of NOR+.
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Affiliation(s)
- Se Wang
- Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
| | - Zhuang Wang
- Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
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6
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Kovacevic G, Sabljic A. Atmospheric oxidation of halogenated aromatics: comparative analysis of reaction mechanisms and reaction kinetics. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:357-369. [PMID: 28002503 DOI: 10.1039/c6em00577b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Atmospheric transport is the major route for global distribution of semi-volatile compounds such as halogenated aromatics as well as their major exposure route for humans. Their major atmospheric removal process is oxidation by hydroxyl radicals. There is very little information on the reaction mechanism or reaction-path dynamics of atmospheric degradation of halogenated benzenes. Furthermore, the measured reaction rate constants are missing for the range of environmentally relevant temperatures, i.e. 230-330 K. A series of recent theoretical studies have provided those valuable missing information for fluorobenzene, chlorobenzene, hexafluorobenzene and hexachlorobenzene. Their comparative analysis has provided additional and more general insight into the mechanism of those important tropospheric degradation processes as well as into the mobility, transport and atmospheric fate of halogenated aromatic systems. It was demonstrated for the first time that the addition of hydroxyl radicals to monohalogenated as well as to perhalogenated benzenes proceeds indirectly, via a prereaction complex and its formation and dynamics have been characterized including the respective transition-state. However, in fluorobenzene and chlorobenzene reactions hydroxyl radical hydrogen is pointing approximately to the center of the aromatic ring while in the case of hexafluorobenzene and hexachlorobenzene, unexpectedly, the oxygen is directed towards the center of the aromatic ring. The reliable rate constants are now available for all environmentally relevant temperatures for the tropospheric oxidation of fluorobenzene, chlorobenzene, hexafluorobenzene and hexachlorobenzene while pentachlorophenol, a well-known organic micropollutant, seems to be a major stable product of tropospheric oxidation of hexachlorobenzene. Their calculated tropospheric lifetimes show that fluorobenzene and chlorobenzene are easily removed from the atmosphere and do not have long-range transport potential while hexafluorobenzene seems to be a potential POP chemical and hexachlorobenzene is clearly a typical persistent organic pollutant.
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Affiliation(s)
- Goran Kovacevic
- Rudjer Boskovic Institute, Division of Physical Chemistry, POB 180, HR-10002 Zagreb, Republic of Croatia.
| | - Aleksandar Sabljic
- Rudjer Boskovic Institute, Division of Physical Chemistry, POB 180, HR-10002 Zagreb, Republic of Croatia.
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Kovacevic G, Sabljic A. Atmospheric oxidation of hexachlorobenzene: New global source of pentachlorophenol. CHEMOSPHERE 2016; 159:488-495. [PMID: 27341152 DOI: 10.1016/j.chemosphere.2016.06.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 06/01/2016] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
Hexachlorobenzene is highly persistent, bioaccumulative, toxic and globally distributed, a model persistent organic pollutant. The major atmospheric removal process for hexachlorobenzene is its oxidation by hydroxyl radicals. Unfortunately, there is no information on the reaction mechanism of this important atmospheric process and the respective degradation rates were measured in a narrow temperature range not of environmental relevance. Thus, the geometries and energies of all stationary points significant for the atmospheric oxidation of hexachlorobenzene are optimized using MP2/6-311G(d,p) method. Furthermore, the single point energies were calculated with G3 method on the optimized minima and transition-states. It was demonstrated for the first time that the addition of hydroxyl radicals to hexachlorobenzene proceeds indirectly, via a prereaction complex. In the prereaction complex the hydroxyl radical is almost perpendicular to the aromatic ring while oxygen is pointing to its center. In contrast, in the transition state it is nearly parallel with the aromatic ring. The reliable rate constants are calculated for the first time for the atmospheric oxidation of hexachlorobenzene for all environmentally relevant temperatures. It was also demonstrated for the first time that pentachlorophenol is the major stable product in the addition of hydroxyl radicals to hexachlorobenzene and that atmosphere seems to be a new global secondary source of pentachlorophenol.
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Affiliation(s)
- Goran Kovacevic
- Rudjer Boskovic Institute, Division of Physical Chemistry, POB 180, HR-10002 Zagreb, Croatia
| | - Aleksandar Sabljic
- Rudjer Boskovic Institute, Division of Physical Chemistry, POB 180, HR-10002 Zagreb, Croatia.
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8
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Bian C, Wang S, Liu Y, Jing X. Thermal stability of phenolic resin: new insights based on bond dissociation energy and reactivity of functional groups. RSC Adv 2016. [DOI: 10.1039/c6ra07597e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Based on bisphenol-F-like model molecules, the bond dissociation energies and Fukui function were calculated to interpret the relationship between the atomistic structure and thermal properties of the phenolic resin.
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Affiliation(s)
- Cheng Bian
- Department of Applied Chemistry
- School of Science
- Xi'an Jiaotong University
- Xi'an
- China
| | - Shujuan Wang
- Department of Applied Chemistry
- School of Science
- Xi'an Jiaotong University
- Xi'an
- China
| | - Yuhong Liu
- Department of Chemical Engineering
- School of Chemical Engineering and Technology
- Xi'an Jiaotong University
- Xi'an
- China
| | - Xinli Jing
- Department of Applied Chemistry
- School of Science
- Xi'an Jiaotong University
- Xi'an
- China
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Wang S, Song X, Hao C, Gao Z, Chen J, Qiu J. Elucidating triplet-sensitized photolysis mechanisms of sulfadiazine and metal ions effects by quantum chemical calculations. CHEMOSPHERE 2015; 122:62-69. [PMID: 25496743 DOI: 10.1016/j.chemosphere.2014.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 11/02/2014] [Indexed: 06/04/2023]
Abstract
Sulfadiazine (SDZ) mainly proceeds triplet-sensitized photolysis with dissolved organic matter (DOM) in the aquatic environment. However, the mechanisms underlying the triplet-sensitized photolysis of SDZ with DOM have not been fully worked out. In this study, we investigated the mechanisms of triplet-sensitized photolysis of SDZ(0) (neutral form) and SDZ(-) (anionic form) with four DOM analogues, i.e., fluorenone (FL), thioxanthone (TX), 2-acetonaphthone (2-AN), and 4-benzoylbenzoic acid (CBBP), and three metal ions (i.e., Mg(2+), Ca(2+), and Zn(2+)) effects using quantum chemical calculations. Results indicated that the triplet-sensitized photolysis mechanism of SDZ(0) with FL, TX, and 2-AN was hydrogen transfer, and with CBBP was electron transfer along with proton transfer (for complex SDZ(0)-CBBP2) and hydrogen transfer (for complex SDZ(0)-CBBP1). The triplet-sensitized photolysis mechanisms of SDZ(-) with FL, TX, and CBBP was electron transfer along with proton transfer, and with 2-AN was hydrogen transfer. The triplet-sensitized photolysis product of both SDZ(0) and SDZ(-) was a sulfur dioxide extrusion product (4-(2-iminopyrimidine-1(2H)-yl)aniline), but the formation routs of the products for SDZ(0) and SDZ(-) were different. In addition, effects of the metal ions on the triplet-sensitized photolysis of SDZ(0) and SDZ(-) were different. The metal ions promoted the triplet-sensitized photolysis of SDZ(0), but inhibited the triplet-sensitized photolysis of SDZ(-).
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Affiliation(s)
- Se Wang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Xuedan Song
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Ce Hao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
| | - Zhanxian Gao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Jieshan Qiu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
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Rocha CMR, Rodrigues JAR, Moran PJS, Custodio R. An interpretation of the phenol nitration mechanism in the gas phase using G3(MP2)//B3-CEP theory. J Mol Model 2014; 20:2524. [PMID: 25433598 DOI: 10.1007/s00894-014-2524-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 11/07/2014] [Indexed: 11/30/2022]
Abstract
G3(MP2)//B3-CEP theory was applied to study the mechanism of phenol nitration in the gas phase, as promoted by the electrophile NO2 (+). The results of studying this mechanism at the G3(MP2)//B3-CEP level pointed to the occurrence of a single-electron transfer (SET) from the aromatic π-system to the nitronium ion prior to σ-complex formation. The formation of an initial π-complex between the nitronium ion and phenol was not observed. Excellent agreement between the activation barriers predicted by G3(MP2)//B3-CEP and those yielded by other, more accurate, versions of the G3 theory showed that the former is a useful tool for studying reaction mechanisms, as G3(MP2)//B3-CEP is much less computationally expensive than other high-level methods.
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11
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Wang S, Hao C, Gao Z, Chen J, Qiu J. Theoretical investigations on direct photolysis mechanisms of polychlorinated diphenyl ethers. CHEMOSPHERE 2014; 111:7-12. [PMID: 24997893 DOI: 10.1016/j.chemosphere.2014.03.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 02/20/2014] [Accepted: 03/07/2014] [Indexed: 06/03/2023]
Abstract
Polychlorinated diphenyl ethers (PCDEs) are a focus of current environmental concern as a group of ubiquitous potential persistent organic pollutants. There are still significant gaps in our knowledge concerning the photolysis mechanisms of PCDEs. In this study, the direct photolysis mechanisms of PCDEs were investigated by density functional theory. The direct photolysis of PCDEs has three potential reaction pathways including photodechlorination, C-O bond photodissociation, and PCDFs formation. Taking a representative PCDE (i.e., CDE8) for example, we found that C-Cl bond dissociation is the rate-determining step for the photodechlorination. Chlorobenzene is predicted to be photoproduct of CDE8 through the photodissociation of the C-O bond. Furthermore, the calculated mean bond dissociation energies of both C-Cl and C-O bonds of 20 PCDEs decrease with the increased degree of chlorination. It is also found that the photoactivity of PCDEs increases with an increase of chlorination degree by evaluating the average charge of Cl atoms and mean bond dissociation energies of C-Cl and C-O bonds from reaction thermodynamics. Our findings provided a new insight into the mechanisms of direct photolysis of PCDEs, which may be useful in the future in utilizing quantum chemistry calculation in investigating the behavior and fate of organic pollutants in the environment.
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Affiliation(s)
- Se Wang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Ce Hao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
| | - Zhanxian Gao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Jieshan Qiu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
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Elucidating photodehalogenation mechanisms of polychlorinated and polybrominated dibenzo-p-dioxins and dibenzofurans and Mg2+ effects by quantum chemical calculations. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.03.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Han D, Li J, Cao H, He M, Hu J, Yao S. Theoretical investigation on the mechanisms and kinetics of OH-initiated photooxidation of dimethyl phthalate (DMP) in atmosphere. CHEMOSPHERE 2014; 95:50-57. [PMID: 24011893 DOI: 10.1016/j.chemosphere.2013.07.087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/22/2013] [Accepted: 07/30/2013] [Indexed: 06/02/2023]
Abstract
The atmospheric OH-initiated degradation mechanisms of dimethy phthalate (DMP) are analyzed at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. The principal products detected experimentally are confirmed by this study while several major intermediates are reported for the first time. Additionally, the pathway scheme of hydroxylation reaction of DMP is proposed. The results about initial steps indicate that hydroxyl radical is most likely to be added to the ortho-carbon atom among additional reactions, while H atoms in methyl group are the most favorable to be abstracted by the OH radical. The rate constants of the elementary reactions over the temperature of 200-400 K were deduced using RRKM theory. The overall rate constant of the title reaction is 1.18×10(-12) cm(3) molecule(-1) s(-1) at 298 K and 760 Torr while H abstraction reactions predominate. According to the rate constants given at different temperatures, the Arrhenius equation is fitted. The atmospheric half life of DMP with respect to OH is estimated to be 6.8 days.
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Affiliation(s)
- Dandan Han
- Environmental Research Institute, Shandong University, Jinan 250100, PR China
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Wang S, Hao C, Gao Z, Chen J, Qiu J. Theoretical investigation on photodechlorination mechanism of polychlorinated biphenyls. CHEMOSPHERE 2014; 95:200-205. [PMID: 24055025 DOI: 10.1016/j.chemosphere.2013.08.066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 08/07/2013] [Accepted: 08/16/2013] [Indexed: 06/02/2023]
Abstract
Photodechlorination is a key process affecting the fate and effect of polychlorinated biphenyls (PCBs) in the environment. However, there are still numerous gaps in our knowledge, which become apparent in photodechlorination mechanism of PCBs. We investigated the conformations of 35 PCB congeners in the ground state and the first triplet excited state (T1), and predicted the photodechlorination pathway of the PCBs by calculating bond dissociation energies of the C-Cl bonds and activation energies of the C-Cl bond dissociation in the excited T1 state. Results show that the torsional degree of the two benzene rings of the PCBs depends on the number of ortho chlorines because of steric effect in the ground state. The two benzene rings of the PCBs with low photoreactivity tend to be coplanar and their torsional degree becomes lower in the excited T1 state compared with those in the ground state. The serious deformation and non-coplane of the benzene rings of some PCBs (e.g. PCB138) in the excited T1 state reduces the conjugation between the two benzene rings, implying that these PCBs have high photoreactivity. The dissociation of the C-Cl bond is the rate-determining step in the photodechlorination reactions of PCBs when the hydrogen donor is methanol. The main photodechlorination pathways predicted in this study are in good agreement with previous experimental results. Our results have provided new insights into mechanism of PCBs photodechlorination, which could be useful in the future in utilizing quantum chemistry calculation in investigating the environmental behavior and fate of organic pollutants.
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Affiliation(s)
- Se Wang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
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Kovacevic G, Sabljic A. Mechanisms and reaction-path dynamics of hydroxyl radical reactions with aromatic hydrocarbons: the case of chlorobenzene. CHEMOSPHERE 2013; 92:851-856. [PMID: 23694732 DOI: 10.1016/j.chemosphere.2013.04.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 02/22/2013] [Accepted: 04/15/2013] [Indexed: 06/02/2023]
Abstract
All geometries and energies significant for the first step of tropospheric degradation of chlorobenzene were characterized using the MP2/6-31+G(d,p) and G3 methods. A pre-reaction complex for the addition of OH radical to chlorobenzene was found and the associated transition state was determined for the first time. The reaction path for the association of OH radical and chlorobenzene into the pre-reaction complex was extrapolated from the selected low frequency normal mode of pre-reaction complex. The reaction rate constant for addition of OH radical to chlorobenzene was determined for the temperature range 230-330K, using RRKM theory and G3 energies. The calculated rate constants are in agreement with the experimental results. Regioselectivity was also determined for the title reaction from the ratio of respective reaction rates and our results are in very good agreement with the experimental results, which show the dominance of the ortho and para channels as well as a negligible contribution by the ipso channel.
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Affiliation(s)
- Goran Kovacevic
- Institute Rudjer Boskovic, POB 180, HR-10002 Zagreb, Croatia
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