ABSTRACT

Global reactivity descriptors of isopropyl acetate (IPA) and thermo-kinetic aspects of its oxidation via OH radicals have been studied. Transition state theory (TST) was utilized to estimate the bimolecular rate constants. Ten oxidation pathways have been investigated, and all of them are exothermic. The potential energy diagram has been sketched using different pre- and post-reactive complexes for all reaction pathways. Rate coefficient calculations were obtained directly by connecting the separated reactants with different transition states. The results indicate that the reaction of IPA with OH radicals occurs in the ground state rather than the excited state, and the rate constants obtained directly and from the effective approach are the same, which confirmed the accuracy of the estimated pre-reactive complexes and the reaction mechanism. Rate constants and branching ratios show that hydrogen atom abstraction from the iso C − H (C₂ atom) bond is the most kinetically preferable route up to 1000 K, while at higher temperatures, H-atom abstraction from the out-of-plane CH₃ group (C₃ atom) became the most dominant route with high competition with that of the in-plane CH₃ group (C₄ atom).

摘要

研究了乙酸异丙酯 (IPA) 的整体反应性描述符及其通过 OH 自由基氧化的热动力学方面。利用过渡态理论（TST）来估计双分子速率常数。已经研究了十种氧化途径，它们都是放热的。使用所有反应途径的不同反应前和反应后复合物绘制了势能图。通过连接具有不同过渡态的分离反应物直接获得速率系数计算。结果表明，IPA与OH自由基的反应发生在基态而不是激发态，并且直接获得的速率常数与有效方法获得的速率常数相同，这证实了估计的预反应配合物的准确性和反应机理。异C – H（C ₂原子）键是直至 1000 K 时动力学上最优选的途径，而在更高温度下，从面外 CH ₃基团（C ₃原子）中夺取 H 原子成为最主要的途径与面内CH ₃基团（C ₄原子）具有高度竞争性。