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Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model

Acetaldehyde (CH(3)CHO) is ubiquitous in interstellar space and is important for astrochemistry as it can contribute to the formation of amino acids through reaction with nitrogen containing chemical species. Quantum chemical and reaction kinetics studies are reported for acetaldehyde formation from...

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Autores principales: Ben Chouikha, Islem, Kerkeni, Boutheïna, Ouerfelli, Ghofrane, Makroni, Lily, Nyman, Gunnar
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9241153/
https://www.ncbi.nlm.nih.gov/pubmed/35873325
http://dx.doi.org/10.1039/d2ra03555c
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author Ben Chouikha, Islem
Kerkeni, Boutheïna
Ouerfelli, Ghofrane
Makroni, Lily
Nyman, Gunnar
author_facet Ben Chouikha, Islem
Kerkeni, Boutheïna
Ouerfelli, Ghofrane
Makroni, Lily
Nyman, Gunnar
author_sort Ben Chouikha, Islem
collection PubMed
description Acetaldehyde (CH(3)CHO) is ubiquitous in interstellar space and is important for astrochemistry as it can contribute to the formation of amino acids through reaction with nitrogen containing chemical species. Quantum chemical and reaction kinetics studies are reported for acetaldehyde formation from the chemical reaction of C((3)P) with a methanol molecule adsorbed at the eighth position of a cubic water cluster. We present extensive quantum chemical calculations for total spin S = 1 and S = 0. The UωB97XD/6-311++G(2d,p) model chemistry is employed to optimize the structures, compute minimum energy paths and zero-point vibrational energies of all reaction steps. For the optimized structures, the calculated energies are refined by CCSD(T) single point computations. We identify four transition states on the triplet potential energy surface (PES), and one on the singlet PES. The reaction mechanism involves the intermediate formation of CH(3)OCH adsorbed on the ice cluster. The rate limiting step for forming acetaldehyde is the C–O bond breaking in CH(3)OCH to form adsorbed CH(3) and HCO. We find two positions on the reaction path where spin crossing may be possible such that acetaldehyde can form in its singlet spin state. Using variational transition-state theory with multidimensional tunnelling we provide thermal rate constants for the energetically rate limiting step for both spin states and discuss two routes to acetaldehyde formation. As expected, quantum effects are important at low temperatures.
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spelling pubmed-92411532022-07-22 Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model Ben Chouikha, Islem Kerkeni, Boutheïna Ouerfelli, Ghofrane Makroni, Lily Nyman, Gunnar RSC Adv Chemistry Acetaldehyde (CH(3)CHO) is ubiquitous in interstellar space and is important for astrochemistry as it can contribute to the formation of amino acids through reaction with nitrogen containing chemical species. Quantum chemical and reaction kinetics studies are reported for acetaldehyde formation from the chemical reaction of C((3)P) with a methanol molecule adsorbed at the eighth position of a cubic water cluster. We present extensive quantum chemical calculations for total spin S = 1 and S = 0. The UωB97XD/6-311++G(2d,p) model chemistry is employed to optimize the structures, compute minimum energy paths and zero-point vibrational energies of all reaction steps. For the optimized structures, the calculated energies are refined by CCSD(T) single point computations. We identify four transition states on the triplet potential energy surface (PES), and one on the singlet PES. The reaction mechanism involves the intermediate formation of CH(3)OCH adsorbed on the ice cluster. The rate limiting step for forming acetaldehyde is the C–O bond breaking in CH(3)OCH to form adsorbed CH(3) and HCO. We find two positions on the reaction path where spin crossing may be possible such that acetaldehyde can form in its singlet spin state. Using variational transition-state theory with multidimensional tunnelling we provide thermal rate constants for the energetically rate limiting step for both spin states and discuss two routes to acetaldehyde formation. As expected, quantum effects are important at low temperatures. The Royal Society of Chemistry 2022-06-29 /pmc/articles/PMC9241153/ /pubmed/35873325 http://dx.doi.org/10.1039/d2ra03555c Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/
spellingShingle Chemistry
Ben Chouikha, Islem
Kerkeni, Boutheïna
Ouerfelli, Ghofrane
Makroni, Lily
Nyman, Gunnar
Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title_full Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title_fullStr Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title_full_unstemmed Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title_short Quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
title_sort quantum chemical study of the reaction paths and kinetics of acetaldehyde formation on a methanol–water ice model
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9241153/
https://www.ncbi.nlm.nih.gov/pubmed/35873325
http://dx.doi.org/10.1039/d2ra03555c
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