1
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Unexpected formation of 2-methyl-1H-naphtho [2, 3-d] imidazole via decarboxylation governed mechanistic pathway. Chem Phys 2023. [DOI: 10.1016/j.chemphys.2022.111735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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2
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Nandi A, Martin JML. Thermally-Activated Tunneling in the Two-Water Bridge Catalyzed Tautomerization of Phosphinylidene Compounds. Chemphyschem 2022; 23:e202200396. [PMID: 35867911 PMCID: PMC9804263 DOI: 10.1002/cphc.202200396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/15/2022] [Indexed: 01/05/2023]
Abstract
Phosphinylidenes are an important class of organophosphorus compounds that can exhibit tautomerization between tricoordinated P(III) hydroxide (R1 R2 POH) and a pentacoordinated P(V) oxide (R1 R2 P(O)H) form. Herein we show, using the canonical variational transition state theory combined with multidimensional small-curvature tunneling approximation, the dominance of proton tunneling in the two-water-bridged tautomerizations of phosphinous acid and model phosphinylidenes comprising phosphosphinates, H-phosphonates, H-phosphinates and secondary phosphine oxides. Based on the studied system, the contribution of thermally-activated tunneling is predicted to speed up the semiclassical reaction rate by ca. threefold to as large as two orders of magnitude at 298.15 K in the gas phase. The large KIE and the concavity in the Arrhenius plots are further fingerprints of tunneling. The simulations also predicted that the rapid tunneling rate and short half-life span for the forward reaction, as opposed to the reverse reaction in fluorinated secondary phosphine oxides, would result in P(V) being elusive and only P(III) being isolable, which agrees with previous experiments where only P(III) was detected by IR and NMR spectroscopy. We also explored the role of solvent and predicted tunneling to be substantial.
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Affiliation(s)
- Ashim Nandi
- Department of Molecular Chemistry and Materials ScienceWeizmann Institute of Science7610001RehovotIsrael
| | - Jan M. L. Martin
- Department of Molecular Chemistry and Materials ScienceWeizmann Institute of Science7610001RehovotIsrael
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3
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Mandal N, Das A, Hajra C, Datta A. Stereoelectronic and dynamical effects dictate nitrogen inversion during valence isomerism in benzene imine. Chem Sci 2022; 13:704-712. [PMID: 35173935 PMCID: PMC8769061 DOI: 10.1039/d1sc04855d] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/14/2021] [Indexed: 01/23/2023] Open
Abstract
Non-classical processes such as heavy-atom tunneling and post transition-state dynamics govern stereoselectivity for benzene imine ⇌ 1H-azepine.
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Affiliation(s)
- Nilangshu Mandal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, West Bengal, India
| | - Ankita Das
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, West Bengal, India
| | - Chandralekha Hajra
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, West Bengal, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, West Bengal, India
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4
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Vijayakumar S, Wilmouth DM. Atmospheric fate of formyl chloride and mechanisms of the gas-phase reactions with OH radicals and Cl atoms. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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5
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Viegas LP, M. Nunes C, Fausto R. Spin-forbidden heavy-atom tunneling in the ring-closure of triplet cyclopentane-1,3-diyl. Phys Chem Chem Phys 2021; 23:5797-5803. [DOI: 10.1039/d1cp00076d] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The putative spin-forbidden heavy-atom tunneling process for the ring closure of cyclopentane-1,3-diyl at cryogenic temperatures is confirmed with calculations employing the weak-coupling formulation of nonadiabatic transition state theory.
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Affiliation(s)
- Luís P. Viegas
- University of Coimbra
- CQC
- Department of Chemistry
- 3004-535 Coimbra
- Portugal
| | - Cláudio M. Nunes
- University of Coimbra
- CQC
- Department of Chemistry
- 3004-535 Coimbra
- Portugal
| | - Rui Fausto
- University of Coimbra
- CQC
- Department of Chemistry
- 3004-535 Coimbra
- Portugal
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6
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7
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Nunes CM, Viegas LP, Wood SA, Roque JPL, McMahon RJ, Fausto R. Heavy‐Atom Tunneling Through Crossing Potential Energy Surfaces: Cyclization of a Triplet 2‐Formylarylnitrene to a Singlet 2,1‐Benzisoxazole. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Cláudio M. Nunes
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Luís P. Viegas
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Samuel A. Wood
- Department of Chemistry University of Wisconsin-Madison Madison WI 53706-1322 USA
| | - José P. L. Roque
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Robert J. McMahon
- Department of Chemistry University of Wisconsin-Madison Madison WI 53706-1322 USA
| | - Rui Fausto
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
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8
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9
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Nunes CM, Viegas LP, Wood SA, Roque JPL, McMahon RJ, Fausto R. Heavy‐Atom Tunneling Through Crossing Potential Energy Surfaces: Cyclization of a Triplet 2‐Formylarylnitrene to a Singlet 2,1‐Benzisoxazole. Angew Chem Int Ed Engl 2020; 59:17622-17627. [PMID: 32558100 DOI: 10.1002/anie.202006640] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Cláudio M. Nunes
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Luís P. Viegas
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Samuel A. Wood
- Department of Chemistry University of Wisconsin-Madison Madison WI 53706-1322 USA
| | - José P. L. Roque
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
| | - Robert J. McMahon
- Department of Chemistry University of Wisconsin-Madison Madison WI 53706-1322 USA
| | - Rui Fausto
- University of Coimbra CQC Department of Chemistry 3004-535 Coimbra Portugal
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10
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Mandal N, Pal AK, Gain P, Zohaib A, Datta A. Transition-State-like Planar Structures for Amine Inversion with Ultralong C-C Bonds in Diamino- o-carborane and Diamino- o-dodecahedron. J Am Chem Soc 2020; 142:5331-5337. [PMID: 32090580 DOI: 10.1021/jacs.0c00181] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Umbrella-like inversion of pyramidalized amines proceed through a planar transition state (TS). Stabilization of the TS through N(lone-pair) → σ*(C-C) "negative hyperconjugation" in diamino-o-carborane (1) causes rapid inversion in the amine, which results in the observation of a planarized -NH2 from the X-ray crystal structure. This proceeds through quantum mechanical tunneling across the small and narrow barrier (low pyramidalization). Tuning this secondary orbital (donor-acceptor) interaction for various derivatives of 1 and diamino-o-dodecahedron (2) provides a rational approach toward increasing dC-C to as large as 2.001, 2.011, and 1.807 Å for 1b (amino oxide-o-carborane), 1i (di-N,N-dimethylamino-o-carborane), and 2g (di-N,N-diisopropylamino-o-dodecahedron), respectively.
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Affiliation(s)
- Nilangshu Mandal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India
| | - Arun K Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India
| | - Pranab Gain
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India
| | - Ahsan Zohaib
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India
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11
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Jestilä JS, Iker Z, Ryding MJO, Uggerud E. The unimolecular dissociation of magnesium chloride squarate (ClMgC 4O 4−) and reductive cyclooligomerisation of CO on magnesium. Org Biomol Chem 2020; 18:9499-9510. [DOI: 10.1039/d0ob01994a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclooligomerisation to squarate is initiated by the coupling of two CO units in MgCl−.
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Affiliation(s)
- Joakim S. Jestilä
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
| | - Zsuzsanna Iker
- Budapest University of Technology and Economics
- Department of Organic Chemistry and Technology
- Budapest
- Hungary
| | - Mauritz J. O. Ryding
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
| | - Einar Uggerud
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
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12
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Arbitman JK, Michel CS, Castro C, Karney WL. Calculations Predict That Heavy-Atom Tunneling Dominates Möbius Bond Shifting in [12]- and [16]Annulene. Org Lett 2019; 21:8587-8591. [PMID: 31613106 DOI: 10.1021/acs.orglett.9b03185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The contribution of heavy-atom tunneling to reactions of [12]- and [16]annulene was probed using small-curvature tunneling rate calculations. At the CCSD(T)/cc-pVDZ//M06-2X/cc-pVDZ level, tunneling is predicted to account for more than 50% of the rate for Möbius bond shifting and ca. 35% of the rate for electrocyclization in [12]annulene, and over 80% of the rate for Möbius bond shifting in [16]annulene, at temperatures at which these reactions have been observed experimentally.
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Affiliation(s)
- Jessica K Arbitman
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Cameron S Michel
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Claire Castro
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - William L Karney
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
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13
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Kowalik M, Ashraf C, Damirchi B, Akbarian D, Rajabpour S, van Duin ACT. Atomistic Scale Analysis of the Carbonization Process for C/H/O/N-Based Polymers with the ReaxFF Reactive Force Field. J Phys Chem B 2019; 123:5357-5367. [PMID: 31145615 DOI: 10.1021/acs.jpcb.9b04298] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During the carbonization process of raw polymer precursors, graphitic structures can evolve. The presence of these graphitic structures affects mechanical properties of the carbonized carbon fibers. To gain a better understanding of the chemistry behind the evolution of these structures, we performed atomistic-scale simulations using the ReaxFF reactive force field. Three different polymers were considered as a precursor: idealized ladder PAN (polyacrylonitrile), a proposed oxidized PAN, and poly( p-phenylene-2,6-benzobisoxazole). We determined the underlying molecular details of polymer conversion into a carbon fiber structure. Because these are C/H/O/N-based polymers, we first developed an improved force field for C/H/O/N chemistry based on the density functional theory data with a particular focus on N2 formation kinetics and its interactions with polymer-associated radicals formed during the carbonization process. Then, using this improved force field, we performed atomistic-scale simulations of the initial stage of the carbonization process for the considered polymers. On the basis of our simulation data, the molecular pathways for the formation of low-molecular-weight gas species and all-carbon ring formation were determined. We also examined the possible alignment of the developed all-carbon 6-membered ring clusters, which is crucial for the further graphitic structure evolution.
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14
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Michel CS, Lampkin PP, Shezaf JZ, Moll JF, Castro C, Karney WL. Tunneling by 16 Carbons: Planar Bond Shifting in [16]Annulene. J Am Chem Soc 2019; 141:5286-5293. [PMID: 30845804 DOI: 10.1021/jacs.8b13131] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Midsized annulenes are known to undergo rapid π-bond shifting. Given that heavy-atom tunneling plays a role in planar bond shifting of cyclobutadiene, we computationally explored the contribution of heavy-atom tunneling to planar π-bond shifting in the major (CTCTCTCT, 5a) and minor (CTCTTCTT, 6a) known isomers of [16]annulene. UM06-2X/cc-pVDZ calculations yield bond-shifting barriers of ca. 10 kcal/mol. The results also reveal extremely narrow barrier widths, suggesting a high probability of tunneling for these bond-shifting reactions. Rate constants were calculated using canonical variational transition state theory (CVT) as well as with small curvature tunneling (SCT) contributions, via direct dynamics. For the major isomer 5a, the computed SCT rate constant for bond shifting at 80 K is 0.16 s-1, corresponding to a half-life of 4.3 s, and indicating that bond shifting is rapid at cryogenic temperatures despite a 10 kcal/mol barrier. This contrasts with the CVT rate constant of 8.0 × 10-15 s-1 at 80 K. The minor isomer 6a is predicted to undergo rapid bond shifting via tunneling even at 10 K. For both isomers, bond shifting is predicted to be much faster than competing conformation change despite lower barriers for the latter process. The preference for bond shifting represents cases of tunneling control in which the preferred reaction is dominated by heavy-atom motions. At all temperatures below -50 °C, tunneling is predicted to dominate the bond shifting process for both 5a and 6a. Thus, [16]annulene is predicted to be an example of tunneling by 16 carbons. Bond shifting in both isomers is predicted to be rapid at temperatures accessible by solution-phase NMR spectroscopy, and an experiment is proposed to verify these predictions.
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Affiliation(s)
- Cameron S Michel
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Philip P Lampkin
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Jonathan Z Shezaf
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Joseph F Moll
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Claire Castro
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - William L Karney
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
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15
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Jana K, Ganguly B. DFT studies on quantum mechanical tunneling in tautomerization of three-membered rings. Phys Chem Chem Phys 2018; 20:28049-28058. [DOI: 10.1039/c8cp03963a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Amino–imino and keto–enol tautomerization processes in three-membered ring systems have been explored to examine the role of quantum mechanical tunneling along with aromaticity. The DFT calculations shed light on the role of aromaticity in tautomerization processes and as perceived this property may not contribute entirely to facilitate the formation of tautomeric forms.
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Affiliation(s)
- Kalyanashis Jana
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility)
- CSIR-Central Salt and Marine Chemicals Research Institute
- Bhavnagar-364002
- India
- Academy of Scientific and Innovative Research
| | - Bishwajit Ganguly
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility)
- CSIR-Central Salt and Marine Chemicals Research Institute
- Bhavnagar-364002
- India
- Academy of Scientific and Innovative Research
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16
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Sadhukhan T, Das D, Kalekar P, Avasare V, Pal S. Fenton’s Reagent Catalyzed Release of Carbon Monooxide from 1,3-Dihydroxy Acetone. J Phys Chem A 2017; 121:4569-4577. [DOI: 10.1021/acs.jpca.7b03676] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Tumpa Sadhukhan
- Department
of Chemistry, Indian Institution of Technology Bombay, Mumbai 400076, India
| | - Dharitri Das
- Department
of Chemistry, Indian Institution of Technology Bombay, Mumbai 400076, India
| | - Pratik Kalekar
- Department
of Chemistry, Sir Parashurambhau College, Pune 411030, India
| | - Vidya Avasare
- Department
of Chemistry, Sir Parashurambhau College, Pune 411030, India
| | - Sourav Pal
- Department
of Chemistry, Indian Institution of Technology Bombay, Mumbai 400076, India
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17
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Karmakar S, Datta A. Tunneling Control: Competition between 6π-Electrocyclization and [1,5]H-Sigmatropic Shift Reactions in Tetrahydro-1H-cyclobuta[e]indene Derivatives. J Org Chem 2017; 82:1558-1566. [DOI: 10.1021/acs.joc.6b02759] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sharmistha Karmakar
- Department of Spectroscopy, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road,
Jadavpur, 700032 Kolkata, West Bengal, India
| | - Ayan Datta
- Department of Spectroscopy, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road,
Jadavpur, 700032 Kolkata, West Bengal, India
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18
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Vijayakumar S, Kumar A, Rajakumar B. Experimental and computational kinetic investigations for the reactions of Cl atoms with unsaturated ketones in the gas phase. NEW J CHEM 2017. [DOI: 10.1039/c7nj03209a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cl atom initiated photo oxidation of unsaturated ketones.
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Affiliation(s)
- S. Vijayakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Avinash Kumar
- 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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19
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Vijayakumar S, Ramya CB, Kumar A, Rajakumar B. Kinetic investigations of Cl atom initiated photo-oxidation reactions of cyclic unsaturated hydrocarbons in the gas phase: an experimental and theoretical study. NEW J CHEM 2017. [DOI: 10.1039/c7nj01721a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cl atom initiated photo oxidation kinetics of cyclohexene and cycloheptene.
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Affiliation(s)
- S. Vijayakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - C. B. Ramya
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Avinash Kumar
- 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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20
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