Ab initio chemical kinetics of Isopropyl acetate oxidation with OH radicals

Abstract

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). GRAPHICAL ABSTRACT