Atmospheric degradation mechanism of anthracene initiated by OH•: A DFT prediction

Farzaneh Shahsavar; Ehsan Zahedi; Abolfazl Shiroudi; Behzad Chahkandi

doi:10.1016/j.jmgm.2023.108426

Atmospheric degradation mechanism of anthracene initiated by OH^•: A DFT prediction

J Mol Graph Model. 2023 Jun:121:108426. doi: 10.1016/j.jmgm.2023.108426. Epub 2023 Feb 9.

Authors

Farzaneh Shahsavar¹, Ehsan Zahedi², Abolfazl Shiroudi³, Behzad Chahkandi⁴

Affiliations

¹ Department of Chemistry, Shahrood Branch, Islamic Azad University, Shahrood, Iran.
² Department of Chemistry, Shahrood Branch, Islamic Azad University, Shahrood, Iran. Electronic address: e_zahedi@iau-shahrood.ac.ir.
³ Department of Physical Chemistry, Gdansk University of Technology, Narutowicza St 11/12, 80-233, Gdansk, Poland; Research Club, IQneiform Oy, Juva, Finland.
⁴ Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran.

PMID: 36806124
DOI: 10.1016/j.jmgm.2023.108426

Abstract

Density functional theory (DFT) calculations at the M06-2X/def2-TZVP level have been employed to investigate the atmospheric oxidation mechanism of anthracene (ANT) initiated by HO^•. Direct hydrogen atom abstraction from the ANT using HO^• takes place hardly at ambient conditions while addition of HO^• to the C1, C2, and C4 sites are thermodynamically and kinetically more advantageous. The addition reactions are controlled by the aromaticity and the kinetic trends were justified by resonance stabilization energies. The rate constants were calculated by using the Rice-Ramsperger-Kassel-Marcus (RRKM) and canonical transition state theory (CTST) methods in conjugation with zero curvature tunneling (ZCT). The overall RRKM-bimolecular rate constant at ambient conditions is 6.72 × 10^-12 cm³ molecule^-1 s^-1, is negatively dependent on the temperature and can be expressed as k_250-350^1bar=3.92×10^-14exp(1534.9T). Contribution of the AD-C4 path in the overall reaction is about 70-80%, implying that the dependence of overall rate constant on pressure can be ignored. The kinetic data exhibit that the ANT is degraded during its long-range transport in the atmosphere and cannot be classified as persistent organic pollutants.

Keywords: Anthracene; CTST; DFT; RRKM; ZCT.

MeSH terms

Air Pollutants*
Anthracenes
Hydroxyl Radical*
Oxidation-Reduction

Substances

Hydroxyl Radical
Air Pollutants
anthracene
Anthracenes