Kinetics and Products of the Gas-Phase Reactions of 6-Methyl-5-hepten-2-one and trans-Cinnamaldehyde with OH and NO₃ Radicals and O₃ at 296 ± 2 K

6-Methyl-5-hepten-2-one is an atmospheric reaction product of the biogenic emission linalool, and trans-cinnamaldehyde is a model compound for dicarbonyls formed from the OH radical-initiated reaction of naphthalene. These carbonyl compounds react in the atmosphere, and photolysis and the gas-phase reactions of 6-methyl-5-hepten-2-one and trans-cinnamaldehyde with OH radicals, NO3 radicals, and O3 have been investigated at 296 ± 2 K and atmospheric pressure of air. Using relative rate methods, the respective rate constants obtained for the OH radical, NO3 radical, and O3 reactions were (in cm3 molecule-1 s-1 units) as follows: for 6-methyl-5-hepten-2-one: (1.57 ± 0.39) × 10-10, (7.5 ± 3.0) × 10-12, and (3.9 ± 1.5) × 10-16; for trans-cinnamaldehyde: (4.8 ± 1.4) × 10-11, (1.9 ± 0.7) × 10-14, and (2.2 ± 1.8) × 10-18. trans-Cinnamaldehyde was also observed to photolyze. Benzaldehyde was observed and quantified from the OH radical reaction with trans-cinnamaldehyde, with a yield of 0.90 ± 0.39. Acetone and CH3C(O)CH2CH2CHO were observed and quantified from the OH radical and O3 reactions with 6-methyl-5-hepten-2-one, with formation yields of 0.706 ± 0.054 and 0.59 ± 0.13, respectively, from the OH radical reaction and 0.302 ± 0.048 and 0.82 ± 0.21, respectively, from the O3 reaction. The reaction mechanisms are discussed.