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Chi TX, Li XX, Ni S, Bai FY, Pan XM, Zhao Z. Theoretical study on the mechanisms, kinetics and risk assessment of OH radicals and Cl atom initiated transformation of HCFC-235fa in the atmosphere. Phys Chem Chem Phys 2024. [PMID: 39290189 DOI: 10.1039/d4cp02323d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
Hydrochlorofluorocarbons (HCFCs) are important greenhouse gases and ozone-depleting substances. Thus, a thorough understanding of their atmospheric fate is essential for preventing and controlling atmospheric pollution. Herein, the atmospheric transformation mechanism of CF3CH2CClF2 (HCFC-235fa) by the OH radical and the Cl atom was carried out at the dual-level of CCSD(T)/aug-cc-pVTZ//M06-2X/6-311+G(d,p). The reaction rate coefficients were calculated using the multistructural canonical variational transition state theory with small curvature tunneling (MS-CVT/SCT) at 200-1000 K. The kMS-CVT/SCT(CF3CH2CClF2 + OH) and kMS-CVT/SCT(CF3CH2CClF2 + Cl) values are 9.05 × 10-15 and 1.95 × 10-17 cm3 molecule-1 s-1 at 297 K, respectively. The results show that the role of OH is more important than Cl in the degradation of CF3CH2CClF2. The atmospheric lifetimes (83 days-77.93 years), ozone destruction potential (0.001-0.023), and global warming potentials (GWP100 = 21.06-5157.35) of CF3CH2CClF2 were assessed, and these results indicate that CF3CH2CClF2 is atmospherically persistent and environmentally unfriendly. The evolution mechanisms of CF3C·HCClF2, CF3C(OO˙)HCClF2, and CF3C(O˙)HCClF2 in the presence of O2, HO2˙, and NO were investigated and discussed. The resulting products of CF3CH2CClF2 are mostly highly oxidized multi-functional compounds in the forms of aldehydes, ketones, and organic nitrates. A computational assessment of acute and chronic toxicities was performed at three levels of nutrition in order to improve the understanding of the potential toxicity of CF3CH2CClF2 and its degradation products to the aquatic environment. The acidification potential of CF3CH2CClF2 was calculated to be 1.141 and presumed to contribute to the formation of acid rain. The results may contribute to describing HCFCs' atmospheric fate, persistence, and environmental risks.
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Affiliation(s)
- Tai-Xing Chi
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, People's Republic of China.
| | - Xin-Xin Li
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, People's Republic of China.
| | - Shuang Ni
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, People's Republic of China.
| | - Feng-Yang Bai
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, People's Republic of China.
- Key Laboratory of Cluster Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Xiu-Mei Pan
- Institute of Functional Material Chemistry, National & Local United Engineering Lab for Power Battery, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
| | - Zhen Zhao
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, People's Republic of China.
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Chang Ping, Beijing 102249, People's Republic of China
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Dash MR, Mishra SS. Mechanistic and kinetic approach on methyl isocyanate (CH 3NCO) with OH and Cl. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2124933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Infrared absorption cross section and radiative forcing efficiency features of four hydrofluoropolyethers: Performance of some DFT functionals. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Holtomo O, Rhyman L, Nsangou M, Ramasami P, Motapon O. Reaction of •OH with CHCl=CH-CHF2 and its atmospheric implication for future environmental-friendly refrigerant. PURE APPL CHEM 2021. [DOI: 10.1515/pac-2021-0116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
In order to understand the atmospheric implication of the chlorinated hydrofluoroolefin (HFO), the geometrical structures and the IR absorption cross sections of the stereoisomers 1-chloro-3,3-difluoropropene were studied using the B3LYP/6-31G(3df) and M06-2X/6-31G(3df) methods in the gas phase. The cis-trans isomerization was assessed using the M06-2X/6-311++G(3df,p)//6-31+G(3df,p) method. The latter method was also employed for thermochemistry and the rate coefficients of the reactions of •OH with the cis- and trans-isomers in the temperature ranging from 200 to 400 K. The computational method CCSD/cc-pVTZ//M06-2X/6-31+G(3df,p) was used to benchmark the rate coefficients. It turns out that, the trans-isomer is more stable than cis-isomer and the trans- to cis-isomerization is thermodynamically unfavorable. The rate coefficient follows the Gaussian law with respect to the inverse of temperature. At the global temperature of stratosphere, the calculated rate coefficients served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). This yielded lifetimes of 4.31 and 7.31 days and POCPs of 3.80 and 2.23 for the cis- and trans-isomer, respectively. The radiative forcing efficiencies gave 0.0082 and 0.0152 W m−2 ppb−1 for the cis- and trans-isomer, respectively. The global warming potential approached zero for both stereoisomers at 20, 100, and 500 years time horizons.
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Affiliation(s)
- Olivier Holtomo
- Department of Physics , Faculty of Science, University of Bamenda , Bambili P.O. Box 39 , Cameroon
- Department of Physics , Faculty of Science, University of Maroua , Maroua P.O. Box 814 , Cameroon
| | - Lydia Rhyman
- Department of Chemistry , Computational Chemistry Group, Faculty of Science, University of Mauritius , Réduit 80837 Mauritius
- Department of Chemical Sciences , Centre for Natural Product Research, University of Johannesburg , Doornfontein , Johannesburg 2028 , South Africa
| | - Mama Nsangou
- Department of Physics , Higher Teacher's Training College, University of Maroua , Maroua P.O. Box 46 , Cameroon
- Department of Physics , Faculty of Science, University of Ngaoundéré , Ngaoundéré P.O. Box 454 , Cameroon
| | - Ponnadurai Ramasami
- Department of Chemistry , Computational Chemistry Group, Faculty of Science, University of Mauritius , Réduit 80837 Mauritius
- Department of Chemical Sciences , Centre for Natural Product Research, University of Johannesburg , Doornfontein , Johannesburg 2028 , South Africa
| | - Ousmanou Motapon
- Department of Physics , Faculty of Science, University of Maroua , Maroua P.O. Box 814 , Cameroon
- Laboratory of Fundamental Physics, Faculty of Science, University of Douala , Douala P.O. Box 24157 , Cameroon
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Theoretical investigation of the atmospheric implication for the reaction of •OH radical with CF 2C(CH 3)-CX 3, X = H, F. J Mol Graph Model 2021; 106:107905. [PMID: 33984816 DOI: 10.1016/j.jmgm.2021.107905] [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: 12/31/2020] [Revised: 02/05/2021] [Accepted: 03/16/2021] [Indexed: 11/23/2022]
Abstract
The atmospheric implication of the hydrofluoroolefines (HFO) CF2C(CH3)-CX3, X=(H,F), through the reactions with •OH radical were assessed using the M06-2X/6-311++G(df,p)//6-31+G(df,p) method. The rate coefficient was calculated over the temperature range 200-500 K, and was accurately expressed in non-Arrhenius form exp(a+bT-1+cT-2) cm3molecule-1s-1, where a, b, and c are real constants. This served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP), which yielded lifetimes of 0.39 and 3.53 days and POCPs of 51.00 and 3.57 for X = H and F, respectively. The radiative forcing efficiencies (RFEs) were also estimated at G96LYP/6-311G(df,p) along with the global warming potentials (GWPs). The results showed negligible impact towards global warming for the HFOs.
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Temperature-dependent oxidation of BSCAPE molecule in methanol medium. J Mol Graph Model 2021; 105:107850. [PMID: 33592351 DOI: 10.1016/j.jmgm.2021.107850] [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: 12/15/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 11/23/2022]
Abstract
Temperature-dependent solvation free energy and oxidation by free energy of ionization of 2-Phenylethyl (2E)-3-(1-benzenesulfonyl-4,5-dihydroxyphenyl) acrylate (BSCAPE) in methanol medium are the concerns of the present work. This molecule is a relevant phenolic acid enclosing multiple bioactivities. The explicit, implicit and discrete-continuum models of solvation were used. The methanol molecules were coordinated to this acid to form cluster complexes. The dual method M06-2X/6-31++G(d,p)//B3LYP/6-31G(d) was employed along with basis set superposition error correction. The results show that, the free energy of coordination and solvation are distant. Both quantities increase with temperature. From discrete-continuum treatment, there is non-spontaneity of solvation process, while coordination yielded spontaneity and non-spontaneity at cold and hot room temperatures, respectively. The ionization potential in gas phase, decreases with temperature. All the solvation models yielded lower ionization potential than that of gas phase. Thus, it follows that, the increase of temperature and methanol medium favours the oxidation of BSCAPE. Consequently, this favours its metabolism processes.
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Infrared spectra of PEHA molecule and its resistance to oxidation in water and methanol media at 298.15 K: solvent cluster size dependency. J Mol Model 2020; 26:323. [PMID: 33123831 DOI: 10.1007/s00894-020-04584-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 10/21/2020] [Indexed: 12/15/2022]
Abstract
The present work investigates the infrared spectra and solvation free energies (SE) of PEHA ((E)-2-(Pyridin-2-yl) ethyl 3-(3,4-dihydroxyphenyl) acrylate) and their impact on the oxidation. The latter was examined through the ionization potential parameter (IP). These investigations were carried out by the DFT method at B3LYP/6-31G(d) for optimization and frequency calculations and corrected for BSSE. X3LYP/6-311++G(2d,2p) was employed for single-point energy calculations. Water and methanol cluster sizes were used for solvation through the explicit solvent model. Thus, the infrared spectra show that the overview frequencies of PEHA compare well with the experimental results. The intense infrared absorptions of complexes are due to the stretching of O-H bonds of solvent clusters in the range 2600-3850 cm-1. The binding energy per solvent molecule of complexes was calculated and shows that water and methanol clusters mimic the liquid state as from 5 to 10 solvent molecules. The SE of PEHA increases with the increase of the cluster size of water and methanol in the direction of the limit. The latter was censured by the solvation done using the combined explicit-implicit solvent model. As for IP parameter, the results are largely above the IP limit and lower than the IP from gas phase. Thus, water and methanol media have an effect of lowering the IP of PEHA compound. Consequently, both media favour the oxidation of PEHA molecule, which facilitates its metabolism in human organism.
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Holtomo O, Motapon O, Nsangou M. DFT Study of Photochemical Properties and Radiative Forcing Efficiency Features of the Stereoisomers cis- and trans-CHCl═CH-CF 3. J Phys Chem A 2019; 123:10437-10445. [PMID: 31697499 DOI: 10.1021/acs.jpca.9b08089] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The accurate assessment of radiative forcing efficiency (RFE) of a greenhouse gas is based on the precise knowledge of its structure and infrared absorption spectrum. The present work investigates the UV-vis absorption spectra and IR absorption spectra that are used for the determination of RFE of the short-lived compounds, cis- and trans-CHCl═CHCF3 (CTFP). These investigations were carried out with six different density functional theory (DFT) methods B3LYP, CAM-B3LYP, M06, M06-2X, TPSS0, and ωB97X-D associated to the basis set 6-31G(3df). Therefrom, the relative populations of the two states cis and trans for temperatures over the range 220-370 K at 1 atm and along the atmospheric altitude were assessed. It turns out that trans-CTFP is the abundant component between the two states. This review reveals that B3LYP and M06 reproduce well the experimental results of UV-vis spectra of trans-CTFP. As for cis-CTFP, EOM-CCSD is not well fitted by DFT methods. The cis- to trans-CTFP isomerization leads to the red shift for DFT methods and to the blue shift in regard to EOM-CCSD and experimental results. The IR absorption spectra are well fitted by B3LYP over the range 500-1600 cm-1 and TPSS0 over 1300-2000 cm-1 for both stereoisomers. Moreover, the root-mean-square errors (RMSEs) of frequencies from experimental data are lower for B3LYP and TPSS0 for both systems. The computed IR absorption band strengths over 500-2000 cm-1 for cis- and over 600-1800 cm-1 for trans-CTFP are consistent with the experiment. The relevant descriptor RFEs of the climate effect were calculated using a narrow band model for a constant vertical profile and then corrected with a lifetime factor for different computational methods. The computed values correlate well with the experimental results for both stereoisomers except M06-2X and TPSS0. It is worth noting that, for both systems, the intense radiative forcing spectra are located at frequencies ranging in 1000-1200 cm-1. The lower forcings of trans-CTFP lying in the atmospheric window region 800-1000 cm-1 are greater than those of cis-CTFP. Therefore, RFE(trans-CTFP) = 1.127 RFE(cis-CTFP).
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Affiliation(s)
- Olivier Holtomo
- Department of Physics, Faculty of Science , University of Bamenda , P.O. Box 39, Bambili , Cameroon.,Department of Physics, Faculty of Science , University of Maroua , P.O. Box 814, Maroua , Cameroon
| | - Ousmanou Motapon
- Department of Physics, Faculty of Science , University of Maroua , P.O. Box 814, Maroua , Cameroon
| | - Mama Nsangou
- Department of Physics, Higher Teachers Training College , University of Maroua , P.O. Box 46, Maroua , Cameroon
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Ye JT, Bai FY, Pan XM. Computational study of H-abstraction reactions from CH 3OCH 2CH 2Cl/CH 3CH 2OCH 2CH 2Cl by Cl atom and OH radical and fate of alkoxy radicals. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:23467-23484. [PMID: 27614635 DOI: 10.1007/s11356-016-7505-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
UNLABELLED Multichannel gas-phase reactions of CH3OCH2CH2Cl/CH3CH2OCH2CH2Cl with chlorine atom and hydroxyl radical have been investigated using ab initio method and canonical variational transition-state dynamic computations with the small-curvature tunneling correction. Further energetic information is refined by the coupled-cluster calculations with single and double excitations (CCSD)(T) method. Both hydrogen abstraction and displacement processes are carried out at the same level. Our results reveal that H-abstraction from the -OCH2- group is the dominant channel for CH3OCH2CH2Cl by OH radical or Cl atom, and from α-CH2 of the group CH3CH2- is predominate for the reaction CH3CH2OCH2CH2Cl with Cl/OH. The contribution of displacement processes may be unimportant due to the high barriers. The values of the calculated rate constants reproduce remarkably well the available experiment data. Standard enthalpies of formation for reactants and product radicals are calculated by isodesmic reactions. The Arrhenius expressions are given within 220-1200 K. The atmospheric lifetime, ozone depleting potential (ODP), ozone formation potential (OFP), and global warming potential (GWP) of CH3OCH2CH2Cl/CH3CH2OCH2CH2Cl are investigated. Meanwhile, the atmospheric fate of the alkoxy radicals are also researched using the same level of theory. To shed light on the atmospheric degradation, a mechanistic study is obtained, which indicates that reaction with O2 is the dominant path for the decomposition of CH3OCH(O•)CH2Cl, the C-C bond scission reaction is the primary reaction path in the consumption of CH3CH(O•)OCH2CH2Cl in the atmosphere. HIGHLIGHTS Ab initio method and canonical variational transition-state theory are employed to study the kinetic nature of hydrogen abstraction reactions of CH3OCH2CH2Cl/CH3CH2OCH2CH2Cl with Cl atom and OH radical and fate of alkoxy radicals (CH3OCH(O•)CH2Cl/CH3CH(O•)OCH2CH2Cl).
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Affiliation(s)
- Jin-Ting Ye
- Faculty of Chemistry, Institute of Functional Material Chemistry, Northeast Normal University, 130024, Changchun, People's Republic of China
| | - Feng-Yang Bai
- Faculty of Chemistry, Institute of Functional Material Chemistry, Northeast Normal University, 130024, Changchun, People's Republic of China
| | - Xiu-Mei Pan
- Faculty of Chemistry, Institute of Functional Material Chemistry, Northeast Normal University, 130024, Changchun, People's Republic of China.
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Betowski D, Bevington C, Allison TC. Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:790-7. [PMID: 26647007 DOI: 10.1021/acs.est.5b04154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Halogenated chemical substances are used in a broad array of applications, and new chemical substances are continually being developed and introduced into commerce. While recent research has considerably increased our understanding of the global warming potentials (GWPs) of multiple individual chemical substances, this research inevitably lags behind the development of new chemical substances. There are currently over 200 substances known to have high GWP. Evaluation of schemes to estimate radiative efficiency (RE) based on computational chemistry are useful where no measured IR spectrum is available. This study assesses the reliability of values of RE calculated using computational chemistry techniques for 235 chemical substances against the best available values. Computed vibrational frequency data is used to estimate RE values using several Pinnock-type models, and reasonable agreement with reported values is found. Significant improvement is obtained through scaling of both vibrational frequencies and intensities. The effect of varying the computational method and basis set used to calculate the frequency data is discussed. It is found that the vibrational intensities have a strong dependence on basis set and are largely responsible for differences in computed RE values.
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Affiliation(s)
- Don Betowski
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Environmental Sciences Division, P.O. Box 93478, Las Vegas, Nevada 89193-3478, United States
| | - Charles Bevington
- U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Risk Assessment Division, 1200 Pennsylvania Avenue, N. W., Mail Code: 7408M, Washington, D.C. 20460, United States
| | - Thomas C Allison
- Material Measurement Laboratory, National Institute of Standards and Technology , 100 Bureau Drive, Stop 8320, Gaithersburg, Maryland 20899-8320, United States
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Bai FY, Liu YJ, Wang X, Sun YQ, Pan XM. Atmospheric chemistry of CF3(CX2)2CH2OH: rate coefficients and temperature dependence of reactions with chlorine atoms and the subsequent pathways of alkyl and alkoxy radicals (X = H, F). RSC Adv 2016. [DOI: 10.1039/c6ra10840g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The atmospheric and kinetic properties of CF3(CX2)2CH2OH (X = H, F) with chlorine atoms were studied by density functional and canonical variational transition state theories in conjunction with the small-curvature tunneling correction.
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Affiliation(s)
- Feng-Yang Bai
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- 130024 Changchun
- People’s Republic of China
| | - You-Jun Liu
- Faculty of Physics
- Aviation University of Air Force
- 130022 Changchun
- People’s Republic of China
| | - Xu Wang
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- 130024 Changchun
- People’s Republic of China
| | - Yan-Qiu Sun
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- 130024 Changchun
- People’s Republic of China
| | - Xiu-Mei Pan
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- 130024 Changchun
- People’s Republic of China
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Balaganesh M, Dash MR, Rajakumar B. Experimental and Computational Investigation on the Gas Phase Reaction of Ethyl Formate with Cl Atoms. J Phys Chem A 2014; 118:5272-8. [DOI: 10.1021/jp502963w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Balaganesh
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Manas Ranjan Dash
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - B. Rajakumar
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
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Kinetics, mechanism and thermochemistry of the gas phase reactions of CF3CH2OCH2CF3 with OH radicals: A theoretical study. J Fluor Chem 2014. [DOI: 10.1016/j.jfluchem.2014.02.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Mechanism, kinetics and atmospheric fate of CF3CHCH2, CF3CFCH2, and CF3CFCF2 by its reaction with OH-radicals: CVT/SCT/ISPE and hybrid meta-DFT methods. J Mol Graph Model 2014; 48:60-9. [DOI: 10.1016/j.jmgm.2013.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/30/2013] [Accepted: 12/02/2013] [Indexed: 11/17/2022]
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15
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Assessment of theoretical methods for the study of hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation (IUPAC Technical Report). PURE APPL CHEM 2013. [DOI: 10.1351/pac-rep-10-02-38] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Global climate change is a major concern as it leads to an increase in the
average temperature of the earth’s atmosphere. The existence and
persistence of some gaseous species in the atmosphere contribute to global
warming. Experimental techniques are used to study the kinetics and degradation
of global warming gases. However, quantum mechanical methods are also useful for
the kinetic and radiative forcing study of global warming species and can
precede experimental investigations. Research has also been targeted to develop
more adapted procedures using ab initio and density functional theory (DFT)
methods. This report provides a global perspective, in simplified manner, of the
theoretical studies of the degradation of gas species in the atmosphere with an
emphasis on the hydrogen abstraction kinetics of global warming gas species
during their degradation and byproduct formation. En route, the results obtained
from these studies are analysed and compared with experimental data where
available. Our analyses indicate that the theoretical predictions are in
agreement with experimental findings but the predicted parameters are dependent
on the method being used. Theoretical methods are used to predict the
thermodynamic parameters of reactions, and, with relevance to this report, the
global warming potential (GWP) index can also be calculated. This report can be
useful for future investigations involving global warming gaseous species while
providing suggestions on how computations can fill in data gaps when
experimental data are unavailable.
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Srinivasulu G, Rajakumar B. Theoretical Investigations on the Kinetics of H-Abstraction Reactions from CF3CH(OH)CF3 by OH Radicals. J Phys Chem A 2013; 117:4534-44. [DOI: 10.1021/jp4006907] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- G. Srinivasulu
- Department of Chemistry, Indian Institute of Technology, Madras, Chennai 600036, India
| | - B. Rajakumar
- Department of Chemistry, Indian Institute of Technology, Madras, Chennai 600036, India
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Balaganesh M, Rajakumar B. Rate Coefficients and Reaction Mechanism for the Reaction of OH Radicals with (E)-CF3CH═CHF, (Z)-CF3CH═CHF, (E)-CF3CF═CHF, and (Z)-CF3CF═CHF between 200 and 400 K: Hybrid Density Functional Theory and Canonical Variational Transition State Theory Calculations. J Phys Chem A 2012; 116:9832-42. [DOI: 10.1021/jp3077276] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Balaganesh
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - B. Rajakumar
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
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18
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An Environmentally Friendly Class of Fluoropolyether: α,ω-Dialkoxyfluoropolyethers. APPLIED SCIENCES-BASEL 2012. [DOI: 10.3390/app2020351] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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19
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Kokkila SI, Bera PP, Francisco JS, Lee TJ. A group increment scheme for infrared absorption intensities of greenhouse gases. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2011.11.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Bravo I, Díaz-de-Mera Y, Aranda A, Moreno E, Nutt DR, Marston G. Radiative efficiencies for fluorinated esters: indirect global warming potentials of hydrofluoroethers. Phys Chem Chem Phys 2011; 13:17185-93. [DOI: 10.1039/c1cp21874c] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Bravo I, Aranda A, Hurley MD, Marston G, Nutt DR, Shine KP, Smith K, Wallington TJ. Infrared absorption spectra, radiative efficiencies, and global warming potentials of perfluorocarbons: Comparison between experiment and theory. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jd014771] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Iván Bravo
- Physical Chemistry Department; University of Castilla-La Mancha; Ciudad Real Spain
| | - Alfonso Aranda
- Physical Chemistry Department; University of Castilla-La Mancha; Ciudad Real Spain
| | - Michael D. Hurley
- Systems Analytics and Environmental Sciences Department; Ford Motor Company; Dearborn Michigan USA
| | - George Marston
- Department of Chemistry; University of Reading; Reading UK
| | - David R. Nutt
- Department of Chemistry; University of Reading; Reading UK
| | - Keith P. Shine
- Department of Meteorology; University of Reading; Reading UK
| | - Kevin Smith
- Space Science and Technology Department; Rutherford Appleton Laboratory; Didcot UK
| | - Timothy J. Wallington
- Systems Analytics and Environmental Sciences Department; Ford Motor Company; Dearborn Michigan USA
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Design strategies to minimize the radiative efficiency of global warming molecules. Proc Natl Acad Sci U S A 2010; 107:9049-54. [PMID: 20439762 DOI: 10.1073/pnas.0913590107] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A strategy is devised to screen molecules based on their radiative efficiency. The methodology should be useful as one additional constraint when determining the best molecule to use for an industrial application. The strategy is based on the results of a recent study where we examined molecular properties of global warming molecules using ab initio electronic structure methods to determine which fundamental molecular properties are important in assessing the radiative efficiency of a molecule. Six classes of perfluorinated compounds are investigated. For similar numbers of fluorine atoms, their absorption of radiation in the IR window decreases according to perfluoroethers > perfluorothioethers approximately sulfur/carbon compounds > perfluorocarbons > perfluoroolefins > carbon/nitrogen compounds. Perfluoroethers and hydrofluorethers are shown to possess a large absorption in the IR window due to (i) the C horizontal line O bonds are very polar, (ii) the C-O stretches fall within the IR window and have large IR intensity due to their polarity, and (iii) the IR intensity for C-F stretches in which the fluorine atom is bonded to the carbon that is bonded to the oxygen atom is enhanced due to a larger C horizontal line F bond polarity. Lengthening the carbon chain leads to a larger overall absorption in the IR window, though the IR intensity per bond is smaller. Finally, for a class of partially fluorinated compounds with a set number of electronegative atoms, the overall absorption in the IR window can vary significantly, as much as a factor of 2, depending on how the fluorine atoms are distributed within the molecule.
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Blowers P, Lownsbury JM. Carbon dioxide emission implications if hydrofluorocarbons are regulated: a refrigeration case study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:1526-1529. [PMID: 20050659 DOI: 10.1021/es9023354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The U.S. is strongly considering regulating hydrofluorocarbons (HFCs) due to their global climate change forcing effects. A drop-in replacement hydrofluoroether has been evaluated using a gate-to-grave life cycle assessment of greenhouse gas emissions for the trade-offs between direct and indirect carbon dioxide equivalent emissions compared to a current HFC and a historically used refrigerant. The results indicate current regulations being considered may increase global climate change.
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Affiliation(s)
- Paul Blowers
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, Arizona 85721-0011, USA.
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Torres FJ, Ochoa-Herrera V, Blowers P, Sierra-Alvarez R. Ab initio study of the structural, electronic, and thermodynamic properties of linear perfluorooctane sulfonate (PFOS) and its branched isomers. CHEMOSPHERE 2009; 76:1143-1149. [PMID: 19428046 DOI: 10.1016/j.chemosphere.2009.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2008] [Revised: 03/20/2009] [Accepted: 04/03/2009] [Indexed: 05/27/2023]
Abstract
Structural, electronic, and thermodynamic properties of linear perfluorooctane sulfonate (PFOS) and its trifluoromethyl-branched isomers (i.e. 1-CF(3)- to 6-CF(3)-PFOS) were theoretically studied by means of ab initio density functional theory (DFT) calculations with the B3LYP functional and a 6-31++G(d,p) basis set. The anionic form of linear PFOS and its trifluromethyl-branched isomers were considered for the initial construction of the computational models; subsequently, H(+), Li(+), and Na(+) were added as counter-ions to study their effect on the properties under investigation. Insignificant changes with respect to the anions were observed in the structure of both the protonated and salt forms due to the presence of these counter-ions. However, important differences in the electrostatic potential maps as well as HOMO and LUMO molecular orbitals were observed for the various forms of PFOS. The linear and branched PFOS ions were identified as the most suitable compounds for interacting with charged species. Furthermore, in the linear anion, it was observed that the LUMO orbital is diffused along the whole fluoro-carbon chain, whereas it is localized to the region close to the ternary carbon in the 4-CF(3)-PFOS, 5-CF(3)-PFOS, and 6-CF(3)-PFOS isomers. The higher accessibility of the LUMO orbital in these branched anions suggests that they have a higher probability of reacting with free radicals when compared with the linear counterpart. This behavior is reflected in the experimental observation that only the branched PFOS isomers were susceptible to reductive defluorination by reduced vitamin B(12) as we previously reported. The relative stability of the linear and branched PFOS in their different forms computed by comparing their calculated Gibbs free energy showed that 1-CF(3)-, 6-CF(3)-, and linear PFOS are the most favorable structures from a thermodynamic point of view.
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Affiliation(s)
- F J Torres
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, 85721, USA.
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Young CJ, Hurley MD, Wallington TJ, Mabury SA. Molecular structure and radiative efficiency of fluorinated ethers: A structure-activity relationship. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008jd010178] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Blowers P, Moline DM, Tetrault KF, Wheeler RR, Tuchawena SL. Global warming potentials of Hydrofluoroethers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:1301-1307. [PMID: 18351109 DOI: 10.1021/es0706201] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Global warming potentials are estimated for hydrofluoroethers, which are an emerging class of compounds for industrial use. Comparisons are made to the limited data previously available before observations about molecular design are discussed. We quantify how molecular structure can be manipulated to reduce environmental impacts due to global warming. We further highlight the need for additional research on this class of compounds so environmental performance can be assessed for green design.
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Affiliation(s)
- Paul Blowers
- Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, Arizona 85721-0011, USA.
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