Yao Xiaoxia, Li Juanqin, Li Zerong
College of Chemistry, Sichuan University, Chengdu 610064, China.
College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
Molecules. 2025 Jun 29;30(13):2805. doi: 10.3390/molecules30132805.
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)). 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.
氢过氧烷基过氧自由基（•OOQOOH）是传统燃料低温氧化化学过程中的重要中间体。在这些物种中，一个氢原子可能从一个不相邻的碳原子迁移到过氧基团，形成二氢过氧烷基自由基（•P(OOH)）。本研究深入探讨了正烷基环己烷中一组110个氢迁移反应的理论动力学，计算了这些反应的高压极限速率常数。根据反应中心及其环境的差异，这些反应进一步分为15个亚类，并通过对每个亚类内的速率常数进行平均得出速率规则。将我们计算得到的•OOQOOH特定氢迁移反应的速率常数与现有机理以及非环烷烃中的类似反应进行比较，发现存在显著差异，强调了针对正烷基环己烷定制精确速率常数的必要性。源自研究的乙基环己烷机理和正丙基环己烷机理已根据本研究的高压极限速率常数进行了改进。对乙基环己烷和正丙基环己烷低温燃烧的模拟表明，与原始机理相比，更新后的机理在特定条件下的预测与实验数据更吻合。
