A combined density functional theory and transition-state theory study of the mechanisms and reaction coefficients of gas-phase ozonolysis of geraniol-trans, 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal is presented. The geometries, energies, and harmonic vibrational frequencies of each stationary point were determined by B3LYP/6-31(d,p), MPW1K/cc-pVDZ, and BH&HLYP/cc-pVDZ methods. According to the calculations, the ozone 6-methyl-5-hepten-2-one reaction is faster than the ozone 6-hydroxy-4-methyl-4-hexenal reaction, but both are slower than the ozone geraniol-trans reaction. By using the BH&HLYP/cc-pVDZ data, a global rate coefficient of 5.9 x 10(-16) cm(3) molecule(-1) s(-1) was calculated, corresponding to the sum of geraniol-trans, 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal reactions with the ozone. These results are in good agreement with the experimental studies.

A density functional theory (DFT) study of the mechanisms of carbonyl oxide reactions from geraniol-trans, 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal ozonolysis is presented. The geometries, energies, and harmonic vibrational frequencies of each stationary point were determined by B3LYP/6-31(d,p) and BH&HLYP/cc-pVDZ methods. According to the calculations, the ozonolysis reactions are initiated by the formation of van der Waals (VDW) complexes to yield primary ozonides, which rapidly open to carbonyl oxide compounds. These carbonyl oxide compounds react to form dioxanes and hydroperoxides. The hydroperoxides react by isomerization to form stable products. Glyoxal and methyl-glyoxal have been identified as the final product from geraniol-trans, 6-methyl-5-hepten-2-one, and 6-hydroxy-4-methyl-4-hexenal ozonolysis. Our results are in good agreement with the experimental studies.

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.