Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes

Hydroperoxyalkylperoxy radicals (•OOQOOH) are important intermediates in the low-temperature oxidation chemistry of conventional fuels. In these species, a hydrogen atom may migrate from a non-adjacent carbon to the peroxy group, forming a dihydroperoxyalkyl radical (•P(OOH)<sub>2</sub>)...

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Main Authors: Xiaoxia Yao, Juanqin Li, Zerong Li
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/13/2805
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author Xiaoxia Yao
Juanqin Li
Zerong Li
author_facet Xiaoxia Yao
Juanqin Li
Zerong Li
author_sort Xiaoxia Yao
collection DOAJ
description Hydroperoxyalkylperoxy radicals (•OOQOOH) are important intermediates in the low-temperature oxidation chemistry of conventional fuels. In these species, a hydrogen atom may migrate from a non-adjacent carbon to the peroxy group, forming a dihydroperoxyalkyl radical (•P(OOH)<sub>2</sub>). This research delves into the theoretical kinetics of a set of 110 H-migration reactions in normal-alkyl cyclohexanes, calculating high-pressure limit rate constants for these reactions. The reactions are further classified into 15 subclasses based on distinctions in the reaction center and its environment, with rate rules derived by averaging the rate constants within each subclass. A comparison of our calculated rate constants for specific H-migration reactions of •OOQOOH with existing mechanisms and similar reactions in non-cyclic alkanes reveals significant disparities, emphasizing the necessity for precise rate constants tailored to normal-alkyl cyclohexanes. Ethyl cyclohexane mechanisms and n-propyl cyclohexane mechanisms sourced from studies have been improved with high-pressure limit rate constants from this study. Simulations of the low-temperature combustion of ethyl cyclohexane and n-propyl cyclohexane show that the predictions from the updated mechanisms align more closely with the experimental data under specific conditions compared to the original mechanism.
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spelling doaj-art-97fab24e45584da4be5d971d604ecae22025-07-11T14:41:07ZengMDPI AGMolecules1420-30492025-06-013013280510.3390/molecules30132805Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl CyclohexanesXiaoxia Yao0Juanqin Li1Zerong Li2College of Chemistry, Sichuan University, Chengdu 610064, ChinaCollege of Chemical Engineering, Sichuan University, Chengdu 610065, ChinaCollege of Chemistry, Sichuan University, Chengdu 610064, ChinaHydroperoxyalkylperoxy radicals (•OOQOOH) are important intermediates in the low-temperature oxidation chemistry of conventional fuels. In these species, a hydrogen atom may migrate from a non-adjacent carbon to the peroxy group, forming a dihydroperoxyalkyl radical (•P(OOH)<sub>2</sub>). This research delves into the theoretical kinetics of a set of 110 H-migration reactions in normal-alkyl cyclohexanes, calculating high-pressure limit rate constants for these reactions. The reactions are further classified into 15 subclasses based on distinctions in the reaction center and its environment, with rate rules derived by averaging the rate constants within each subclass. A comparison of our calculated rate constants for specific H-migration reactions of •OOQOOH with existing mechanisms and similar reactions in non-cyclic alkanes reveals significant disparities, emphasizing the necessity for precise rate constants tailored to normal-alkyl cyclohexanes. Ethyl cyclohexane mechanisms and n-propyl cyclohexane mechanisms sourced from studies have been improved with high-pressure limit rate constants from this study. Simulations of the low-temperature combustion of ethyl cyclohexane and n-propyl cyclohexane show that the predictions from the updated mechanisms align more closely with the experimental data under specific conditions compared to the original mechanism.https://www.mdpi.com/1420-3049/30/13/2805dihydroperoxyalkyl radicalintramolecular H-migrationnormal-alkyl cycloalkaneshigh-pressure limit rate rules
spellingShingle Xiaoxia Yao
Juanqin Li
Zerong Li
Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
Molecules
dihydroperoxyalkyl radical
intramolecular H-migration
normal-alkyl cycloalkanes
high-pressure limit rate rules
title Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
title_full Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
title_fullStr Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
title_full_unstemmed Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
title_short Computational Kinetic Study on the Intramolecular H-Migration of Hydroperoxyalkylperoxy Radicals (•OOQOOH) in Normal-Alkyl Cyclohexanes
title_sort computational kinetic study on the intramolecular h migration of hydroperoxyalkylperoxy radicals •ooqooh in normal alkyl cyclohexanes
topic dihydroperoxyalkyl radical
intramolecular H-migration
normal-alkyl cycloalkanes
high-pressure limit rate rules
url https://www.mdpi.com/1420-3049/30/13/2805
work_keys_str_mv AT xiaoxiayao computationalkineticstudyontheintramolecularhmigrationofhydroperoxyalkylperoxyradicalsooqoohinnormalalkylcyclohexanes
AT juanqinli computationalkineticstudyontheintramolecularhmigrationofhydroperoxyalkylperoxyradicalsooqoohinnormalalkylcyclohexanes
AT zerongli computationalkineticstudyontheintramolecularhmigrationofhydroperoxyalkylperoxyradicalsooqoohinnormalalkylcyclohexanes