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Tayum N, Murugan A, Deka RC, Gour NK, Mishra BK. The molecular level study of the fate of the CH 3CH 2C(O)OCH(O)CH 3 radical derived from ethyl propionate. MOLECULAR SIMULATION 2023. [DOI: 10.1080/08927022.2023.2189975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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Yadav AK, Mishra BK, Singh A, Gour NK. Atmospheric degradation, mechanism and kinetics of ethyl vinyl ketone (CH 2=CHCOCH 2CH 3) initiated by Cl atom: an insight from DFT study. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2100835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
| | | | - Ashutosh Singh
- Department of Chemistry, K.S. Saket PG College, Ayodhya, India
| | - Nand Kishor Gour
- Department of Chemical Sciences, Tezpur University, Tezpur, India
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Phanrang PT, Baruah P, Chandra AK, Mitra S. Auxiliary Therapeutic Role of Cholinergic Agents: Mechanistic Insights into the Antioxidant Behavior of Alzheimer's Disease Drugs. J Phys Chem A 2022; 126:546-556. [PMID: 35050595 DOI: 10.1021/acs.jpca.1c09146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Repurposing of existing drugs toward new therapeutic use(s) has become an emergent area of research in current times. In this context, the antioxidant behavior of eight cholinergic drugs used in the treatment of Alzheimer's disease (AD) was investigated theoretically. The low bond dissociation enthalpy values in all of the compounds advocated for the hydrogen atom transfer mechanism toward the observed antioxidant behavior. The kinetic study for the reaction of the drugs with hydroperoxyl radicals indicated an indirect reaction path owing to the presence of pre- and postreaction complexes. In some cases, the rate constant for the H-abstraction reaction (k = 2.8 × 103 L mol-1 s-1) is found to be close to that of a well-known non-phenolic antioxidant, α-terpinene (k = 4.3 × 103 L mol-1 s-1). Quantification of charge transfer character among the drugs with DNA bases and molecular docking calculations confirmed the groove binding model and predicted the drugs to be safe from DNA damage. A theoretical evaluation of the mechanistic details governing the antioxidant property along with the proven stress reversal ability of these AD drugs provided new insights to design and develop more efficient drugs with dual therapeutic potential.
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Affiliation(s)
| | - Prayasee Baruah
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
| | - Asit K Chandra
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
| | - Sivaprasad Mitra
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
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Ding Z, Tian S, Dang J, Zhang Q. New mechanistic understanding for atmospheric oxidation of isoprene initiated by atomic chlorine. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 801:149768. [PMID: 34438153 DOI: 10.1016/j.scitotenv.2021.149768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 06/13/2023]
Abstract
Isoprene is the most abundant non-methane VOC and a significant SOA contributor. The atmospheric oxidation initiated by atomic chlorine is an important sink for isoprene, especially in certain regions with high Cl concentration, while its detailed oxidation mechanism remains unclear. In this work, we comprehensively investigated the reaction mechanism of isoprene with Cl using quantum chemistry calculation, and first elaborated the specific reaction mechanisms of chloroalkenyl peroxy radicals with HO2/NO and the formation of 2-methylbut-3-enal, highlighting their important roles in the SOA formation. For the initial reactions, Cl additions to terminal carbons and H abstraction from CH3 moiety of isoprene are the predominant reactions, which is consistent with previous research. Following the initial reactions, their subsequent reactions with O2 and HO2 (or NO) under different atmospheric conditions could lead to the formation of 17 highly oxidized molecules (HOMs), of which P10, P12, P16, P17, P19 and P33 generated by the subsequent reactions of the major first-generation products (MVK, CMBO, CMBA and MBO) have been detected in the reaction process of isoprene with Cl in the chamber experiment. In addition to auto-oxidation process, the reaction of chloroalkenyl peroxy radicals with HO2/NO and their subsequent reactions are all easy to occur under atmospheric conditions, which could be crucial contributors to the formation of HOMs and SOA arising from the Cl initiated oxidation of isoprene. This study would be conducive to clarifying the atmospheric oxidation process of isoprene initiated by Cl and providing a new understanding of its SOA formation.
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Affiliation(s)
- Zhezheng Ding
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Shuai Tian
- Department of Cardiology, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518033, China; School of Energy and Power Engineering, Shandong University, Jinan 250061, China
| | - Juan Dang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China
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Hynniewta S, Baidya B, Chandra AK. Theoretical investigation on the kinetics of reaction of methoxyflurane (CH3OCF2CHCl2) with OH radical and its atmospheric impact. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Baidya B, Lily M, Patgiri D, Hynniewta S, Chandra AK. CHF 2CF 2OCHF 2: conformational analysis and direct dynamics study of its reaction with Cl atoms and atmospheric fate. NEW J CHEM 2020. [DOI: 10.1039/c9nj06069c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Conformers of CHF2CF2OCHF2 are identified, and the kinetics of its reaction with Cl atoms and final atmospheric degradation products are studied to assess atmospheric impact.
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Affiliation(s)
- Bidisha Baidya
- Centre for Advanced Studies in Chemistry
- North – Eastern Hill University
- Shillong
- India
| | - Makroni Lily
- Centre for Advanced Studies in Chemistry
- North – Eastern Hill University
- Shillong
- India
| | - Dimpal Patgiri
- Centre for Advanced Studies in Chemistry
- North – Eastern Hill University
- Shillong
- India
| | - Shemphang Hynniewta
- Centre for Advanced Studies in Chemistry
- North – Eastern Hill University
- Shillong
- India
| | - Asit K. Chandra
- Centre for Advanced Studies in Chemistry
- North – Eastern Hill University
- Shillong
- India
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Gour NK, Borthakur K, Paul S, Chandra Deka R. Tropospheric degradation of 2-fluoropropene (CH 3CFCH 2) initiated by hydroxyl radical: Reaction mechanisms, kinetics and atmospheric implications from DFT study. CHEMOSPHERE 2020; 238:124556. [PMID: 31422310 DOI: 10.1016/j.chemosphere.2019.124556] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 08/02/2019] [Accepted: 08/09/2019] [Indexed: 06/10/2023]
Abstract
Degradation of hydrofluoro-olefins (HFOs) with oxidants plays a significant role in the troposphere. Thus, we have investigated detail theoretical calculations of hydroxyl radical (•OH) initiated oxidation of 2-fluoropropene (CH3CFCH2) using M06-2X/6-311++G(d,p) level of theory. Here, we have considered different possible H-abstraction and OH addition for the degradation of CH3CFCH2 molecule. The potential energy analysis shows that OH-addition channels are more dominant than H-abstraction channels. The calculated reaction enthalpies (ΔrH°) and Gibbs free energies (ΔrG°) also suggest that OH-addition reaction channels are more favourable than H-abstraction channels. The overall rate coefficients for CH3CFCH2 + •OH reaction is calculated within the temperature range of 250-450 K. The observed overall rate coefficient (2.01 × 10-11 cm3 molecule-1 s-1) at 298 K for the titled reaction is found to be in good agreement with the earlier reported experimental rate coefficient. The calculated percentage branching ratio shows that the contribution of OH-addition to α-carbon and β-carbon of CH3CFCH2 molecule are 85.10% and 14.20% to the overall rate coefficient while H-abstractions have a negligible contribution. Based on the kinetics calculations, the atmospheric lifetime of the titled molecule is found to be 0.6 days. Further, we have also explored the degradation pathways of OH-addition product radicals and found acetyl fluoride (CH3CFO) and formaldehyde (HCHO) are the end degradation products.
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Affiliation(s)
- Nand Kishor Gour
- Department of Chemical Sciences, Tezpur University, Tezpur, Assam, 784028, India
| | - Kaushik Borthakur
- Department of Chemical Sciences, Tezpur University, Tezpur, Assam, 784028, India
| | - Subrata Paul
- Department of Chemical Sciences, Tezpur University, Tezpur, Assam, 784028, India.
| | - Ramesh Chandra Deka
- Department of Chemical Sciences, Tezpur University, Tezpur, Assam, 784028, India.
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Paul S, Mishra BK, Baruah SD, Deka RC, Gour NK. Atmospheric oxidation of HFE-7300 [n-C 2F 5CF(OCH 3)CF(CF 3) 2] initiated by •OH/Cl oxidants and subsequent degradation of its product radical: a DFT approach. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:907-920. [PMID: 31820248 DOI: 10.1007/s11356-019-06975-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
To understand the atmospheric chemistry of hydrofluoroethers, we have studied the oxidation of a highly fluorinated compound n-C2F5CF(OCH3)CF(CF3)2 (HFE-7300) by OH/Cl oxidants. Here, we have employed M06-2X functional along with a 6-31 + G(d,p) basis set to obtain the optimized structures, various forms of energies, and different modes of frequencies for all species. We have characterized energies of all species on the potential energy surface, and it indicates that H-abstraction from n-C2F5CF(OCH3)CF(CF3)2 by Cl atom is kinetically more dominant than the H-abstraction reaction initiated by OH radical. In contrast, the calculated energy change (ΔrH°298 and ΔrG°298) results govern that OH-initiated H-abstraction reaction is highly exothermic and spontaneous compared to the Cl-initiated H-abstraction reaction. Rate constants are estimated using transition state theory as well as canonical variation transition state theory at the temperature range 200-1000 K and 1 atm pressure. The calculated rate constants of the H-abstraction channels are found to be in good agreement with the reported experimental rate constant at 298 K. Moreover, we have estimated the atmospheric lifetimes of HFE-7300 for the reaction with OH radical and Cl atom and are found to be 1.75 and 153.93 years, respectively. Additionally, the global warming potentials for HFE-7300 molecule are also estimated for 20-, 100-, and 500-year time horizons. Further, subsequent aerial oxidation of product radical (n-C2F5CF(OCH2)CF(CF3)2) in the presence of NO radical is performed, and it produced alkoxy radical via formation of peroxy radical. This alkoxy radical undergoes unimolecular decompositions via two different ways and formed n-C2F5CF(OCHO)CF(CF3)2 and n-C2F5CF(OH) CF(CF3)2 products.
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Affiliation(s)
- Subrata Paul
- Department of Chemical Sciences, Tezpur University Tezpur, Tezpur, Assam, 784028, India
| | - Bhupesh Kumar Mishra
- Department of Chemistry, D. N. Government College, Itanagar, Arunachal Pradesh, 791113, India
| | - Satyajit Dey Baruah
- Department of Chemical Sciences, Tezpur University Tezpur, Tezpur, Assam, 784028, India
| | - Ramesh Chandra Deka
- Department of Chemical Sciences, Tezpur University Tezpur, Tezpur, Assam, 784028, India
| | - Nand Kishor Gour
- Department of Chemical Sciences, Tezpur University Tezpur, Tezpur, Assam, 784028, India.
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Li MY, Bai FY, Pan XM. Theoretical study of H-atom abstraction reactions from CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 by NO3 radical & subsequent degradation. J Mol Graph Model 2019; 93:107453. [DOI: 10.1016/j.jmgm.2019.107453] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/14/2019] [Accepted: 09/16/2019] [Indexed: 11/28/2022]
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