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Asatryan R, Hudzik J, Swihart M. Intramolecular Catalytic Hydrogen Atom Transfer (CHAT). J Phys Chem A 2024; 128:2169-2190. [PMID: 38451855 DOI: 10.1021/acs.jpca.3c06794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Intramolecular catalysis (IntraCat) is the acceleration of a process at one site of a molecule catalyzed by a functional group in the same molecule; an external agent such as a solvent typically facilitates it. Here, we report a general first-principles-based IntraCat mechanism, which strictly occurs within a single molecule with no coreagent being involved─we call it intramolecular catalytic transfer of hydrogen atoms (CHAT). A reactive part of a molecule (chat catalyst moiety or chat agent, represented by -OOH, -COOH, -SH, -CH2OH, -HPO4, or another bifunctional H-donor/acceptor group) catalyzes an interconversion process, such as keto-enol or amino-imino tautomerization, and cyclization in the same molecule, while being regenerated in the process. It can thus be regarded as an intramolecular version of the intermolecular H atom transfer processes mediated by an external molecular catalyst, e.g., dihydrogen, water, or a carboxylic acid. Earlier, we proposed a general mechanistic systematization of intermolecular processes, illustrated in the simplest case of the H2-mediated reactions classified as dihydrogen catalysis [Asatryan, R.; et al. Catal. Rev.: Sci. Eng., 2014, 56, 403-475]. Following this systematization, the CHAT catalysis belongs to the category of relay transfer of H atoms, albeit in an intramolecular manner. A broader class of intramolecular processes includes all types of H-transfer reactions stimulated by an H-migration, which we call self-catalyzed H atom transfer (SC-HAT). The CHAT mechanism comprises a subset of SC-HAT in which the catalytic moiety is regenerated (i.e., acts as a true catalyst and not a reagent). We provide several characteristic examples of CHAT mechanism based on detailed analysis of the corresponding potential energy surfaces. All such cases showed a dramatically reduced activation barrier relative to the corresponding uncatalyzed H-transfer reactions. For example, we show that CHAT can facilitate long-range H-migration in larger molecules and can occur multiple times in one molecule with multiple interconverting groups. It also facilitates amino-imino tautomerization of unsaturated GABA-analogues and peptides, as well as intramolecular cyclization processes to form heterocycles, e.g., oxygenated rings. CHAT pathways may also explain the pH-dependent increase of mutarotation rate of glucose-6-phosphate demonstrated in pioneering experiments that introduced the classical IntraCat concept. In addition, we identify a ground electronic state CHAT pathway as an alternative to the UV-promoted long-range molecular crane keto-enol conversion with a remarkably low activation energy. To initially assess the possible impact of the new keto-enol conversion pathway on combustion of n-alkanes, we present a detailed kinetic analysis of isomerization and decomposition of pentane-2,4-ketohydroperoxide (2,4-KHP). The results are compared with key alternative reactions, including direct dissociation and Korcek channels (for which a new alkyl group migration channel is also identified), revealing the competitiveness of the CHAT pathway across a range of conditions. Taken together, this work provides insight into a general class of reaction pathways that has not previously being systematically considered and that may occur in a broad range of contexts from combustion to atmospheric chemistry to biochemistry.
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Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Jason Hudzik
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Mark Swihart
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
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Hudzik JM, Barekati-Goudarzi M, Khachatryan L, Bozzelli JW, Ruckenstein E, Asatryan R. OH-Initiated Reactions of para-Coumaryl Alcohol Relevant to the Lignin Pyrolysis. Part II. Kinetic Analysis. J Phys Chem A 2020; 124:4875-4904. [DOI: 10.1021/acs.jpca.9b11894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jason M. Hudzik
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | | | - Lavrent Khachatryan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Joseph W. Bozzelli
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14226, United States
| | - Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14226, United States
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Dance I. Computational Investigations of the Chemical Mechanism of the Enzyme Nitrogenase. Chembiochem 2020; 21:1671-1709. [DOI: 10.1002/cbic.201900636] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Ian Dance
- School of Chemistry UNSW Sydney Sydney 2052 Australia
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Asatryan R, Hudzik JM, Bozzelli JW, Khachatryan L, Ruckenstein E. OH-Initiated Reactions of p-Coumaryl Alcohol Relevant to the Lignin Pyrolysis. Part I. Potential Energy Surface Analysis. J Phys Chem A 2019; 123:2570-2585. [DOI: 10.1021/acs.jpca.9b00185] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14226, United States
| | - Jason M. Hudzik
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Joseph W. Bozzelli
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Lavrent Khachatryan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14226, United States
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Asatryan R, Pal Y, Hachmann J, Ruckenstein E. Roaming-like Mechanism for Dehydration of Diol Radicals. J Phys Chem A 2018; 122:9738-9754. [DOI: 10.1021/acs.jpca.8b08690] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Yudhajit Pal
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
- Computational and Data-Enabled Science and Engineering Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Johannes Hachmann
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
- New York State Center of Excellence in Materials Informatics, Buffalo, New York 14203, United States
- Computational and Data-Enabled Science and Engineering Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
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Asatryan R, Ruckenstein E, Hachmann J. Revisiting the polytopal rearrangements in penta-coordinate d 7-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization. Chem Sci 2017; 8:5512-5525. [PMID: 28970931 PMCID: PMC5618771 DOI: 10.1039/c7sc00703e] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/26/2017] [Indexed: 11/28/2022] Open
Abstract
New rearrangement mechanism prototypes are introduced to account for the non-ideal coordination and fluxional behavior of five-coordinate metalo-complexes.
This paper provides a first-principles theoretical investigation of the polytopal rearrangements and fluxional behavior of five-coordinate d7-transition metal complexes. Our work is primarily based on a potential energy surface analysis of the iron tetracarbonyl hydride radical HFe˙(CO)4. We demonstrate the existence of distorted coordination geometries in this prototypical system and, for the first time, introduce three general rearrangement mechanisms, which account for the non-ideal coordination. The first of these mechanisms constitutes a modified version of the Berry pseudorotation via a square-based pyramidal C4v transition state that connects two chemically identical edge-bridged tetrahedral stereoisomers of C2v symmetry. It differs from the classical Berry mechanism, which involves two regular D3h equilibrium structures and a C4v transition state. The second mechanism is related to the famous “tetrahedral jump” hypothesis, postulated by Muetterties for a number of d6 HML4 and H2ML4 complexes. Here, our study suggests two fluxional rearrangement pathways via distinct types of C2v transition states. Both pathways of this mechanism can be described as a single-ligand migration to a vacant position of an “octahedron”, thus interchanging (switching) the apical and basal ligands of the initial quasi-square pyramidal isomer, which is considered as an idealized octahedron with a vacancy. Accordingly, we call this mechanism “octahedral switch”. The third mechanism follows a butterfly-type isomerization featuring a key-angle deformation, and we thus call it “butterfly isomerization”. It connects the quasi-square pyramidal and edge-bridged tetrahedral isomers of HFe˙(CO)4 through a distorted edge-bridged tetrahedral transition state of Cs symmetry. Our paper discusses the overall features of the isomers and rearrangement mechanisms as well as their implications. We rationalize the existence of each stationary point through an electronic structure analysis and argue their relevance for isolobal analogues of HFe˙(CO)4.
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Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering , University at Buffalo , The State University of New York , Buffalo , NY 14260 , USA . ;
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering , University at Buffalo , The State University of New York , Buffalo , NY 14260 , USA . ;
| | - Johannes Hachmann
- Department of Chemical and Biological Engineering , University at Buffalo , The State University of New York , Buffalo , NY 14260 , USA . ; .,New York State Center of Excellence in Materials Informatics , Buffalo , NY 14203 , USA.,Computational and Data-Enabled Science and Engineering Graduate Program , University at Buffalo , The State University of New York , Buffalo , NY 14260 , USA
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Asatryan R, Bennadji H, Bozzelli JW, Ruckenstein E, Khachatryan L. Molecular Products and Fundamentally Based Reaction Pathways in the Gas-Phase Pyrolysis of the Lignin Model Compound p-Coumaryl Alcohol. J Phys Chem A 2017; 121:3352-3371. [PMID: 28406634 DOI: 10.1021/acs.jpca.7b01656] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The fractional pyrolysis of lignin model compound para-coumaryl alcohol (p-CMA) containing a propanoid side chain and a phenolic OH group was studied using the System for Thermal Diagnostic Studies at temperatures from 200 to 900 °C, in order to gain mechanistic insight into the role of large substituents in high-lignin feedstocks pyrolysis. Phenol and its simple derivatives p-cresol, ethyl-, propenyl-, and propyl-phenols were found to be the major products predominantly formed at low pyrolysis temperatures (<500 °C). A cryogenic trapping technique was employed combined with EPR spectroscopy to identify the open-shell intermediates registered at pyrolysis temperatures above 500 °C. These were characterized as radical mixtures primarily consisting of oxygen-linked conjugated radicals. A comprehensive potential energy surface analysis of p-CMA and p-CMA + H atom systems was performed using various DFT protocols to examine the possible role of concerted molecular eliminations and free-radical mechanisms in the formation of major products. Other significant unimolecular concerted reactions along with formation and decomposition of primary radicals are also described and evaluated. The calculations suggest that a set of the chemically activated secondary radical channels is relevant to the low temperature product formation under fractional pyrolysis conditions.
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Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14226, United States
| | - Hayat Bennadji
- Department of Environmental Sciences, Louisiana State University , Baton Rouge, Louisiana 70808, United States
| | - Joseph W Bozzelli
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology , Newark, New Jersey 07102, United States
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14226, United States
| | - Lavrent Khachatryan
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
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Khachatryan L, Xu MX, Wu AJ, Pechagin M, Asatryan R. Radicals and molecular products from the gas-phase pyrolysis of lignin model compounds. Cinnamyl alcohol. JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS 2016; 121:75-83. [PMID: 28344372 PMCID: PMC5363761 DOI: 10.1016/j.jaap.2016.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The experimental results on detection and identification of intermediate radicals and molecular products from gas-phase pyrolysis of cinnamyl alcohol (CnA), the simplest non-phenolic lignin model compound, over the temperature range of 400-800 °C are reported. The low temperature matrix isolation - electron paramagnetic resonance (LTMI-EPR) experiments along with the theoretical calculations, provided evidences on the generation of the intermediate carbon and oxygen centered as well as oxygen-linked, conjugated radicals. A mechanistic analysis is performed based on density functional theory to explain formation of the major products from CnA pyrolysis; cinnamaldehyde, indene, styrene, benzaldehyde, 1-propynyl benzene, and 2-propenyl benzene. The evaluated bond dissociation patterns and unimolecular decomposition pathways involve dehydrogenation, dehydration, 1,3-sigmatropic H-migration, 1,2-hydrogen shift, C-O and C-C bond cleavage processes.
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Affiliation(s)
- Lavrent Khachatryan
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
- Corresponding author. (L. Khachatryan)
| | - Meng-xia Xu
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Ang-jian Wu
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
| | - Mikhail Pechagin
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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Xu MX, Khachatryan L, Baev A, Asatryan R. Radicals from the gas-phase pyrolysis of a lignin model compound: p-coumaryl alcohol. RSC Adv 2016; 6:62399-62405. [PMID: 28458882 DOI: 10.1039/c6ra11372a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The intermediate radicals produced in the gas-phase pyrolysis of one of the main building blocks of lignin - p-coumaryl alcohol (p-CMA) - were investigated using the low temperature matrix isolation technique interfaced with electron paramagnetic resonance spectroscopy (LTMI-EPR). An anisotropic EPR spectrum characterized by a high g-value (>2.0080) and a relatively low saturation coefficient (∼1.40) throughout the high pyrolytic temperature region (700 to 1000 °C) was observed. Theoretical calculations revealed plausible decomposition pathways for p-CMA comprising highly delocalized aromatic radicals. The results provide evidence for a dominant role of oxygen-centered radicals during the pyrolysis of p-CMA.
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Affiliation(s)
- Meng-Xia Xu
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Lavrent Khachatryan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Alexander Baev
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Rubik Asatryan
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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McKee ML. A New Nitrogenase Mechanism Using a CFe8S9 Model: Does H2 Elimination Activate the Complex to N2 Addition to the Central Carbon Atom? J Phys Chem A 2016; 120:754-64. [PMID: 26821350 DOI: 10.1021/acs.jpca.5b10384] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A truncated model of the FeMo cofactor is used to explore a new mechanism for the conversion of N2 to NH3 by the nitrogenase enzyme. After four initial protonation/reduction steps, the H4CFe8S9 cluster has two hydrogen atoms attached to sulfur, one hydrogen bridging two iron centers and one hydrogen bonded to carbon. The loss of the CH and FeHFe hydrogens as molecular hydrogen activates the cluster to addition of N2 to the carbon center. This unique step takes place at a nearly planar four-coordinate carbon center and leads to an intermediate with a significantly weakened N-N bond. A hydrogen attached to a sulfur atom is then transferred to the distal nitrogen atom. Additional prontonation/reduction steps are modeled by adding a hydrogen atom to sulfur and locating the transition states for transfer to nitrogen. The first NH3 is lost in a thermal neutral step, while the second step is endothermic. The loss of H2 activates the complex by reducing the barrier for N2 addition by 3.5 kcal/mol. Since this is the most difficult step in the mechanism, reducing the barrier for this step justifies the "extra expense" of H2 production.
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Affiliation(s)
- Michael L McKee
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
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Asatryan R, Ruckenstein E. Effect of “Reducible” Titania Promotion on the Mechanism of H-Migration in Pd/SiO2 Clusters. Catal Letters 2015. [DOI: 10.1007/s10562-015-1642-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Asatryan R, Ruckenstein E. Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen. CATALYSIS REVIEWS-SCIENCE AND ENGINEERING 2014. [DOI: 10.1080/01614940.2014.953356] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Wang Y, Wei D, Li Z, Zhu Y, Tang M. DFT study on the mechanisms and diastereoselectivities of Lewis acid-promoted ketene-alkene [2 + 2] cycloadditions: what is the role of Lewis acid in the ketene and C = X (X = O, CH₂, and NH) [2 + 2] cycloaddition reactions? J Phys Chem A 2014; 118:4288-300. [PMID: 24874716 DOI: 10.1021/jp500358m] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The detailed mechanisms and diastereoselectivities of Lewis acid-promoted ketene-alkene [2 + 2] cycloaddition reactions have been studied by density functional theory (DFT). Four possible reaction channels, including two noncatalyzed diastereomeric reaction channels (channels A and B) and two Lewis acid (LA) ethylaluminum dichloride (EtAlCl2) catalyzed diastereomeric reaction channels (channels C and D), have been investigated in this work. The calculated results indicate that channel A (associated with product R-configurational cycloputanone) is more energy favorable than channel B (associated with the other product S-configurational cyclobutanone) under noncatalyzed condition, but channel D leading to S-configurational cyclobutanone is more energy-favorable than channel C, leading to R-configurational cycloputanone under a LA-promoted condition, which is consistent with the experimental results. And Lewis acid can make the energy barrier of ketene-alkene [2 + 2] cycloaddition much lower. In order to explore the role of LA in ketene and C = X (X = O, CH2, and NH) [2 + 2] cycloadditions, we have tracked and compared the interaction modes of frontier molecular orbitals (FMOs) along the intrinsic reaction coordinate (IRC) under the two different conditions. Besides by reducing the energy gap between the FMOs of the reactants, our computational results demonstrate that Lewis acid lowers the energy barrier of the ketene and C = X [2 + 2] cycloadditions by changing the overlap modes of the FMOs, which is remarkably different from the traditional FMO theory. Furthermore, analysis of global reactivity indexes has also been performed to explain the role of LA catalyst in the ketene-alkene [2 + 2] cycloaddition reaction.
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Affiliation(s)
- Yang Wang
- The College of Chemistry and Molecular Engineering, Center of Computational Chemistry, Zhengzhou University , Zhengzhou, Henan Province 450001, P.R. China
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Asatryan R, Ruckenstein E. Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways. J Phys Chem A 2013; 117:10912-32. [DOI: 10.1021/jp406878k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rubik Asatryan
- Department of Chemical
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Biological Engineering, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Eli Ruckenstein
- Department of Chemical
and
Biological Engineering, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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