Reactions of NO.sub.3 with aromatic aldehydes: gas-phase kinetics and insights into the mechanism of the reaction

• Published in: Atmospheric chemistry and physics Vol. 21; no. 17; pp. 13537 - 27073
• Main Authors: Ren, Yangang, Zhou, Li, Mellouki, Abdelwahid, Daële, Véronique, Idir, Mahmoud, Brown, Steven S, Ruscic, Branko, Paton, Robert S, McGillen, Max R, Ravishankara, A. R
• Format: Journal Article
• Language: English
• Published: Copernicus GmbH 10.09.2021
• Subjects: Aldehydes
• ISSN: 1680-7316; 1680-7324

Rate coefficients for the reaction of NO.sub.3 radicals with a series of aromatic aldehydes were measured in a 7300 L simulation chamber at ambient temperature and pressure by relative and absolute methods. The rate coefficients for benzaldehyde (BA), ortho-tolualdehyde (O-TA), meta-tolualdehyde (M-TA), para-tolualdehyde (P-TA), 2,4-dimethyl benzaldehyde (2,4-DMBA), 2,5-dimethyl benzaldehyde (2,5-DMBA) and 3,5-dimethyl benzaldehyde (3,5-DMBA) were k.sub.1 = 2.6 ± 0.3, k.sub.2 = 8.7 ± 0.8, k.sub.3 = 4.9 ± 0.5, k.sub.4 = 4.9 ± 0.4, k.sub.5 = 15.1 ± 1.3, k.sub.6 = 12.8 ± 1.2 and k.sub.7 = 6.2 ± 0.6, respectively, in the units of 10.sup.-15 cm.sup.3 molec..sup.-1 s.sup.-1 at 298 ± 2 K. The rate coefficient k.sub.13 for the reaction of the NO.sub.3 radical with deuterated benzaldehyde (benzaldehyde-d.sub.1) was found to be half that of k.sub.1 . The end product of the reaction in an excess of NO.sub.2 was measured to be C.sub.6 H.sub.5 C(O)O.sub.2 NO.sub.2 . Theoretical calculations of aldehydic bond energies and reaction pathways indicate that the NO.sub.3 radical reacts primarily with aromatic aldehydes through the abstraction of an aldehydic hydrogen atom. The atmospheric implications of the measured rate coefficients are briefly discussed.