Night-time Atmospheric Loss Process for Unsaturated Aldehydes:  Reaction with NO₃ Radicals

Abstract

The rate constants for the gas-phase reactions of the NO3 radical with a series of unsaturated aldehydes (acrolein, crotonaldehyde, trans-2-pentenal, trans-2-hexenal, trans-2-heptenal, and cis-4-heptenal) have been measured directly using a flow tube system coupled to a laser-induced fluorescence (LIF) detection system where the NO3 radical was monitored. The kinetic study was conducted in the temperature range from 298 to 433 K to investigate the temperature dependence of these reactions. This work is the first temperature-dependence study for the reactions of the nitrate radical with the above-mentioned aldehydes. The measured room-temperature rate constants for the reaction of NO3 with such unsaturated compounds (in units of 10-14 cm3 molecule-1 s-1) are as follows: acrolein, 0.25 ± 0.04; crotonaldehyde, 1.61 ± 0.19; trans-2-pentenal, 2.88 ± 0.29; trans-2-hexenal, 5.49 ± 0.95; trans-2-heptenal, 9.59 ± 0.19; cis-4-heptenal, 26.40 ± 0.40. The proposed Arrhenius expressions for such reactions of NO3 are, respectively, k 1 = (1.7 ± 3.2) × 10-11 exp[−(3232 ± 355)/T] (cm3 molecule-1 s-1), k 2 = (5.52 ± 0.82) × 10-11 exp[−(2418 ± 57)/T] (cm3 molecule-1 s-1), k 3 = (5.4 ± 0.3) × 10-12 exp[−(1540 ± 200)/T] (cm3 molecule-1 s-1), k 4 = (1.20 ± 0.3) × 10-11 exp[−(926 ± 85)/T] (cm3 molecule-1 s-1), k 5 = (0.8 ± 0.2) × 10-12 exp[−(632 ± 47)/T] (cm3 molecule-1 s-1), and k 6 = (0.2 ± 0.1) × 10-11 exp[−(657± 6.0)/T] (cm3 molecule-1 s-1). Tropospheric lifetimes for these aldehydes have been calculated at night and during the daytime for typical NO3 and OH concentrations showing that both radicals provide an effective tropospheric sink for these compounds and that the night-time reaction with NO3 radical can be an important loss process for these emitted organics and for the NO3 radicals. The present work aims to evaluate the importance of these reactions in the atmosphere and to contribute new data to the study of NO3 reactivity.

Prediction of Rate Constants for Gas‐Phase Reactions of Nitrate Radical with Organic Compounds: A New Structure–Activity Relationship

“…A study by Cabanas et al [11] on a series of trans-2-aldehydes found rate constants which almost double when one carbon atom is added to the chain. The rate constant for the reaction of NO 3 with trans-2-butenal, trans-2-pentenal, trans-2-hexenal and trans-2-heptenal are 1.02, 2.88, 5.49 and 9.59 10 À14 cm 3 molecule À1 s…”

“…[6,7] As the knowledge of the rate constants for the reactions of organic compounds with this radical is important for determination of their atmospheric lifetimes, several studies have been carried out since then to extend the experimental kinetic database of VOC oxidation. [8][9][10][11][12][13][14][15][16] They often concerned oxygenated compounds.…”

Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes

“…In this sense, the study of the reactions of trans-2-pentenal trans-2-hexenal, trans-2-heptenal, n-pentanal, n-hexanal, n-heptanal with OH radical has been carried out recently by Albaladejo et al (2002) by means of PLP/LIF technique at room temperature and as a function of the total pressure. Cabañas et al (2001a, b) also studied the temperature dependence of the reaction of these saturated and unsaturated aldehydes with NO 3 using a fastflow discharge system with LIF detection. The relative rate of these three reactions may define the global distribution of products from the atmospheric oxidation of aldehydes under local conditions.…”

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

“…Relative to summer, nights in winter are longer, colder and more humid, and biogenic VOC emissions tend to be smaller. This allows for a larger fraction of NO 2 to be oxidized to HNO 3 via the N 2 O 5 hydrolysis pathway (Cabañas et al, 2001;Wagner et al, 2013), and colder temperatures favor partitioning of nitrate to the particle phase (Stelson and Seinfeld, 1982). In winter, nighttime HNO 3 production can more efficiently compete with daytime photochemically driven production due to the low photolysis rates and hydroxyl radical concentrations (Wagner et al, 2013;Pusede et al, 2016).…”