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Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives

The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were investigated using density functional theory (DFT) with the ωB97XD and M06–2x functionals, as well as the benchmark CBS-QB3 composite method....

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Autores principales: Shojaei, S.H. Reza, Shiroudi, Abolfazl, Abdel-Rahman, Mohamed A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9626549/
https://www.ncbi.nlm.nih.gov/pubmed/36339763
http://dx.doi.org/10.1016/j.heliyon.2022.e11274
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author Shojaei, S.H. Reza
Shiroudi, Abolfazl
Abdel-Rahman, Mohamed A.
author_facet Shojaei, S.H. Reza
Shiroudi, Abolfazl
Abdel-Rahman, Mohamed A.
author_sort Shojaei, S.H. Reza
collection PubMed
description The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were investigated using density functional theory (DFT) with the ωB97XD and M06–2x functionals, as well as the benchmark CBS-QB3 composite method. Transition state theory (TST) and RRKM theory calculations of rate constants under atmospheric pressure and in the fall-off regime were used to supplement the measured energy profiles. The results show that the formation of propene and bromoacetic acid is the most dominant pathway at the CBS-QB3 composite method, both kinetically and thermodynamically. There was a good agreement with experimental results. Pressures greater than 0.01 bar, corresponding to larger barrier heights are insufficient to ensure saturation of the measured rate coefficient when compared to the RRKM kinetic rates. Natural bond orbitals (NBO) charges, bond orders, bond indices, and synchronicity parameters all point to the considered pathways taking place via a homogenous, first-order concerted, as well as an asynchronous mechanism involving a non-planar cyclic six-membered transition state. The calculated data exhibit that the elongation of the C(α)−O bond length and subsequent polarization of the C(α)(+δ)…O(−δ) bond is the rate-determining step of the considered reactions in the cyclic transition state, which appears to be involved in this type of reaction.
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spelling pubmed-96265492022-11-03 Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives Shojaei, S.H. Reza Shiroudi, Abolfazl Abdel-Rahman, Mohamed A. Heliyon Research Article The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were investigated using density functional theory (DFT) with the ωB97XD and M06–2x functionals, as well as the benchmark CBS-QB3 composite method. Transition state theory (TST) and RRKM theory calculations of rate constants under atmospheric pressure and in the fall-off regime were used to supplement the measured energy profiles. The results show that the formation of propene and bromoacetic acid is the most dominant pathway at the CBS-QB3 composite method, both kinetically and thermodynamically. There was a good agreement with experimental results. Pressures greater than 0.01 bar, corresponding to larger barrier heights are insufficient to ensure saturation of the measured rate coefficient when compared to the RRKM kinetic rates. Natural bond orbitals (NBO) charges, bond orders, bond indices, and synchronicity parameters all point to the considered pathways taking place via a homogenous, first-order concerted, as well as an asynchronous mechanism involving a non-planar cyclic six-membered transition state. The calculated data exhibit that the elongation of the C(α)−O bond length and subsequent polarization of the C(α)(+δ)…O(−δ) bond is the rate-determining step of the considered reactions in the cyclic transition state, which appears to be involved in this type of reaction. Elsevier 2022-10-26 /pmc/articles/PMC9626549/ /pubmed/36339763 http://dx.doi.org/10.1016/j.heliyon.2022.e11274 Text en © 2022 The Author(s) https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Research Article
Shojaei, S.H. Reza
Shiroudi, Abolfazl
Abdel-Rahman, Mohamed A.
Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title_full Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title_fullStr Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title_full_unstemmed Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title_short Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
title_sort computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9626549/
https://www.ncbi.nlm.nih.gov/pubmed/36339763
http://dx.doi.org/10.1016/j.heliyon.2022.e11274
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