Kinetic Analysis for HO2 Addition to Ethylene, Propene, and Isobutene, and Thermochemical Parameters of Alkyl Hydroperoxides and Hydroperoxide Alkyl Radicals

Abstract

Thermochemical kinetic analysis for the reactions of HO2 radical addition to the primary, secondary, and tertiary carbon−carbon double bonds of ethylene, propene, and isobutene are studied using canonical transition state theory (TST). Thermochemical properties of reactants, alkyl hydroperoxides (ROOH), hydroperoxy alkyl radicals (R·OOH), and transition states (TSs) are determined by ab initio and density functional calculations. Enthalpies of formation (ΔHf°298) of product radicals (R·OOH) are determined using isodesmic reactions with group balance at MP4(full)/6-31G(d,p)//MP2(full)/6-31G(d), MP2(full)/6-31G(d), complete basis set model chemistry (CBS-q with MP2(full)/6-31g(d) and B3LYP/6-31g(d) optimized geometries), and density functional (B3LYP/6-31g(d) and B3LYP/6-311+g(3df,2p)//B3LYP/6-31g(d)) calculations. ΔHf°298 of TSs are obtained from the ΔHf°298 of reactants plus energy differences between reactants and TSs. Entropies (S°298) and heat capacities (Cp(T) 300 ≤ T/K ≤ 1500) contributions from vibr...