Thermochemistry and Kinetics for 2-Butanone-3yl Radical (CH3C(=O)CH•CH3) Reactions with O2

Thermochemistry and chemical activation kinetics for the reaction of the secondary radical of 2-butanone, 2-butanone-3yl, with O-3(2) are reported. Thermochemical and kinetic parameters are determined for reactants, transition states structures and intermediates. Standard enthalpies and kinetic parameters are evaluated using ab initio (G3MP2B3 and G3), density functional (B3LYP/6-311g(d, p)) calculations and group additivity (GA). The C-H bond energies are determined for the three carbons of the 2-butanone, showing that the C-H bond energy (BE) on the secondary carbon is low at 90.5 kcalmol(-1). The CH3C(=O)(CHCH3)-C-center dot radical + O-2 association results in chemically-activated peroxy radical with 26 kcalmol(-1) excess of energy. The chemically activated adduct can dissociate to butanone-oxy radical + O, react back to butanone-3yl + O-2, form cyclic ethers or lactones, eliminate HO2 to form an olefinic ketone, or undergo rearrangement via intramolecular abstraction of hydrogen to form hydroperoxide and/or OH radicals. The hydroperoxide-alkyl radical intermediates can undergo further reactions forming cyclic ethers (lactones) and OH radicals. Quantum RRK analysis is used to calculate k(E) and master equation analysis is used for evaluation of pressure fall-off in these chemical activated reaction systems.