Atmospheric oxidation of selected terpenes and related carbonyls: gas-phase carbonyl products

The gas-phase carbonyl products of α-pinene, β-pinene, and d-limonene have been identified and their concentrations measured in experiments involving sunlight irradiations of mixtures of terpene (1-2 ppm) and NO (0.25 ppm) in air. In turn, sunlight irradiations of carbonyl-NO_x mixtures have been carried out for the major high molecular weight carbonyl products of β-pinene (6,6-dimethylbicyclo[3.1.1] heptan-2-one) and d-limonene (4-acetyl-1-methylcyclohexene), and the corresponding carbonyl products have been identified. The nature and yields of these carbonyl products are discussed in terms of oxidation mechanisms involving the OH-terpene, ozone-terpene, OH-carbonyl, and ozone-carbonyl reactions.