Gas-Phase Ozone Reaction Kinetics of C 5 -C 8 Unsaturated Alcohols of Biogenic Interest.

Unsaturated alcohols are volatile organic compounds (VOCs) that characterize the emissions of plants. Changes in climate together with related increases of biotic and abiotic stresses are expected to increase these emissions in the future. Ozonolysis is one of the oxidation pathways that control the fate of unsaturated alcohols in the atmosphere. The rate coefficients of the gas-phase O 3 reaction with seven C 5 -C 8 unsaturated alcohols were determined at 296 K using both absolute and relative kinetic methods. The following rate coefficients (cm 3 molecule -1 s -1 ) were obtained using the absolute method: (1.1 ± 0.2) × 10 -16 for cis -2-penten-1-ol, (1.2 ± 0.2) × 10 -16 for trans -2-hexen-1-ol, (6.4 ± 1.0) × 10 -17 for trans -3-hexen-1-ol, (5.8 ± 0.9) × 10 -17 for cis -3-hexen-1-ol, (2.0 ± 0.3) × 10 -17 for 1-octen-3-ol, and (8.4 ± 1.3) × 10 -17 for trans -2-octen-1-ol. The following rate coefficients (cm 3 molecule -1 s -1 ) were obtained using the relative method: (1.27 ± 0.11) × 10 -16 for trans -2-hexen-1-ol, (5.01 ± 0.30) × 10 -17 for trans -3-hexen-1-ol, (4.13 ± 0.34) × 10 -17 for cis -3-hexen-1-ol, and (1.40 ± 0.12) × 10 -16 for trans -4-hexen-1-ol. Alkenols display high reactivities with ozone with lifetimes in the hour range. Rate coefficients show a strong and complex dependence on the structure of the alkenol, particularly the relative position of the OH group toward the C═C double bond. The results are discussed and compared to both the available literature data and four structure-activity relationship (SAR) methods.