Theoretical Study of the Addition of OH Radicals to trans-Geraniol-(3,7-dimethylocta-2,6-dien-1-ol), 6-Methyl-5-hepten-2-one, and 6-Hydroxy-4-methyl-4-hexenal

Abstract

A combined density functional theory and transition state theory study of the gas-phase addition of OH to 3,7-dimethylocta-2,6-dien-1-ol (trans-geraniol), 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal is presented. In this study, all different possibilities for the addition of the OH radical to the C-C double bonds in trans-geraniol, 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal were considered. The geometries, energies, and harmonic vibrational frequencies at each stationary point were determined at the MPW1K/cc-pVDZ and BH&HLYP/cc-pVDZ levels. Global rate coefficients of 0.94 x 10(-10) and 3.1 x 10(-10) cm(3) molecule(-1) s(-1), 2.11 x 10(-11) and 7.53 x 10(-11) cm(3) molecule(-1) s(-1), and 2.70 x 10(-13), and 4.37 x 10(-12) cm(3) molecule(-1) s(-1) were calculated using data obtained at the BH&HLYP/cc-pVDZ and MPW1K/cc-pVDZ levels of theory. These coefficients correspond to the sum of the rate coefficients of the individual paths for trans-geraniol, 6-hydroxy-4-methyl-4-hexenal, and 6-methyl-5-hepten-2-one, when reacting with OH radicals. The calculated rate coefficients are in good agreement with the available experimental data.