Rate Coefficients for the Gas‐Phase Reaction of Ozone with C5 and C6 Unsaturated Aldehydes

ABSTRACT Emissions of biogenic volatile organic compounds are higher than those from anthropogenic sources. In this work, we studied the kinetics of the reaction of three unsaturated aldehydes (trans‐2‐pentenal, trans‐2‐hexenal, and 2‐methyl‐2‐pentenal) with ozone in a rigid atmospheric simulation chamber coupled to an FTIR spectrometer at four different temperatures (273, 298, 333, and 353 K). Reaction rate constants (× 10−18 cm3 molecule−1 s−1) at 298 K are 1.24 ± 0.06 for trans‐2‐pentenal (t‐2P), 1.37 ± 0.03 for trans‐2‐hexenal (t‐2H), and 1.58 ± 0.20) for 2‐methyl‐2‐pentenal (2M2P). The following Arrhenius expressions were deduced (cm3 molecule−1 s−1): Trans-2-pentenal:kt−2P+O3=1.38±0.73×10−16exp−1406±163/TTrans-2-hexenal:kt−2H+O3=1.79±0.54×10−16exp−1457±90/T2-Methyl-2-pentenal:k2M2P+O3=1.42±0.56×10−17exp−664±124/T The obtained data are presented and compared to those reported in the literature at room temperature, as well as to homologous alkenes. The atmospheric lifetimes with respect to ozone, derived from this study, are estimated to vary between 7 and 10 days.