Ozonolysis of alpha-pinene and beta-pinene: kinetics and mechanism.
A combined quantum-chemical and RRKM/ME (ME--master equation) approach is employed to investigate the structures, energetics, and kinetics of intermediate and stable species, and the yields of stabilized carbonyl oxides and OH radicals from the alpha-pinene and beta-pinene ozonolysis reactions. The cycloaddition of O(3) is highly exothermic, with the reaction energies of 55.1 and 51.1 kcal mol(-1) for alpha- and beta-pinenes, respectively. Cleavage of primary ozonides yields carbonyl oxides with the barrier height of 12.2-17.5 kcal mol(-1). For the prompt reactions of carbonyl oxides from alpha- and beta-pinene ozonolysis, H migration to hydroperoxides represents the dominant pathway over ring closure to dioxiranes. The kinetic calculations indicate a significant portion of stabilization for alpha- and beta-carbonyl oxides. The yields of stabilized carbonyl oxides are estimated to be 0.34 for alpha-pinene and 0.22 for beta-pinene. The applicability of theoretical methods for investigation of oxidation reactions of large hydrocarbon molecules is demonstrated.
Zhang
Dan
D
Department of Atmospheric Sciences, Texas A&M University, College Station, 77843, USA.
Zhang
Renyi
R
D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D003198:Computer Simulation; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D039821:Monoterpenes / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D011789:Quantum Theory
D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds; D039821:Monoterpenes; C010789:beta-pinene; D010126:Ozone; C005451:alpha-pinene