Rate constants for the gas-phase reactions of a series of C3?C6 aldehydes with OH and NO3 radicals

Abstract

By using relative rate methods, rate constants for the gas-phase reactions of OH and NO3 radicals with propanal, butanal, pentanal, and hexanal have been measured at 296 ± 2 K and atmospheric pressure of air. By using methyl vinyl ketone as the reference compound, the rate constants obtained for the OH radical reactions (in units of 10−12 cm3 molecule−1 s−1) were propanal, 20.2 ± 1.4; butanal, 24.7 ± 1.5; pentanal, 29.9 ± 1.9; and hexanal, 31.7 ± 1.5. By using methacrolein and 1-butene as the reference compounds, the rate constants obtained for the NO3 radical reactions (in units of 10−15 cm3 molecule−1 s−1) were propanal, 7.1 ± 0.4; butanal, 11.2 ± 1.5; pentanal, 14.1 ± 1.6; and hexanal, 14.9 ± 1.3. The dominant tropospheric loss process for the aldehydes studied here is calculated to be by reaction with the OH radical, with calculated lifetimes of a few hours during daytime. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 79–84, 2000