Preprints
https://doi.org/10.5194/acp-2021-553
https://doi.org/10.5194/acp-2021-553

  08 Jul 2021

08 Jul 2021

Review status: this preprint is currently under review for the journal ACP.

Investigations on the gas-phase photolysis and OH radical kinetics of nitrocatechols: Implications of intramolecular interactions on their atmospheric behavior

Claudiu Roman1,2, Cecilia Arsene1,2, Iustinian Gabriel Bejan1,2, and Romeo-Iulian Olariu1,2 Claudiu Roman et al.
  • 1“Alexandru Ioan Cuza” University of Iasi, Faculty of Chemistry, Iasi, 11th Carol I, 700506, Romania
  • 2”Alexandru Ioan Cuza” University of Iasi, Integrated Center of Environmental Science Studies in the North Eastern Region - CERNESIM, Iasi, 11th Carol I, 700506, Romania

Abstract. The Environmental Simulation Chamber made of Quartz from the University “Alexandru Ioan Cuza” from Iasi (ESC-Q-UAIC), Romania, was used to investigate for the first time the gas-phase reaction rate coefficients for four nitrocatechols towards OH radicals under simulated atmospheric conditions. Employing relative rate technique at a temperature of 298 ± 2 K and total air pressure of 1 atm, the obtained rate coefficients (in 10−12 cm3×s−1) were as followed: k3NCAT = (3.41 ± 0.37) for 3-nitrocatechol, k4NCAT = (1.27 ± 0.19) for 4-nitrocatechol, k5M3NCAT = (5.55 ± 0.45) for 5-methyl-3-nitrocatechol and k4M5NCAT = (0.92 ± 0.14) for 4-methyl-5-nitrocatechol. For the investigated compounds the photolysis rates in the actinic region, scaled to atmospheric relevant conditions, were evaluated as well. In this case the photolysis rate coefficient values were obtained only for 3-nitrocatechol and 5-methyl-3-nitrocatechol: J3NCAT = (3.06 ± 0.16) × 10−4 s−1 and J5M3NCAT = (2.14 ± 0.18) × 10−4 s−1, respectively. Considering the obtained results our study suggests that photolysis may be the main degradation process for 3-nitrocatechol and 5-methyl-3-nitrocatechol in the atmosphere. Results are discussed in terms of the reactivity of the investigated four nitrocatechols towards OH-radical initiated oxidation and their structural features. The rate coefficient values are also compared with those estimated from the structure-activity relationship for monocyclic aromatic hydrocarbons. Additional comparison with similar compounds is also presented underlining the implications towards possible degradation pathways and atmospheric behavior.

Claudiu Roman et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-553', Cornelius Zetzsch, 20 Aug 2021
  • RC2: 'Comment on acp-2021-553', Anonymous Referee #2, 04 Oct 2021

Claudiu Roman et al.

Claudiu Roman et al.

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Short summary
Gas-phase reaction rate coefficients of OH radicals with four nitrocatechols have been investigated for the first time by using the ESC-Q-UAIC chamber facilities. The reactivity of all investigated nitrocatechols is influenced by the formation of the intramolecular H-bonds that are connected with the deactivating electromeric effect of the NO2 group. For the 3-nitrocatechols compounds, the electromeric effect of the "free" OH group is diminished by the deactivating E- effect of the NO2 group.
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