Chemical Review and Letters

Kinetic and mechanistic insights into the atmospheric hydrogen abstraction of 3-Hydroxybutanal by chlorine

Document Type : Research Article

Authors

Patouossa Issofa
Eric Njankwa Njabon
Tagne Tchamba Sédric
Alphonse Emadak

Physical and Theoretical Chemistry Unit, Laboratory of Applied Physical and Analytical Chemistry, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon.

https://doi.org/10.22034/crl.2025.532470.1648
Abstract
This work investigates the reaction mechanism of hydrogen atom abstraction from 3-hydroxybutanal (3HB) by the chlorine (Cl) radical under atmospheric conditions, a process relevant to the degradation of volatile organic compounds (VOCs). Density Functional Theory (DFT) calculations were carried out at the B3LYP/def2-SVP level to explore five possible abstraction pathways, each involving a distinct hydrogen site within the 3HB molecule. Vibrational frequency analyses confirmed the presence of five corresponding transition states (TS1–TS5). Rate constants for each pathway were computed using KiSThelP software across a temperature range of 278–400 K. The calculated rate constants are 2.5817 × 10¹, 1.6695 × 10-7, 8.3975 × 10², 1.1758 × 10-11, and 2.3056 × 10-10 cm³•molecule-1•s-1 for pathways 1 through 5, respectively. These results indicate that hydrogen abstraction at site 3 (pathway 3) is the most kinetically favorable. Thermodynamic analysis supports this conclusion, with the product from pathway 3 exhibiting the lowest Gibbs free energy and reaction enthalpy (–22.25 kcal/mol), confirming it as the most thermodynamically stable. All pathways are exothermic and exergonic. These findings provide detailed mechanistic insight into the atmospheric reactivity of 3HB and may be extended to other structurally related VOCs, contributing to a better understanding of atmospheric oxidation processes.

Graphical Abstract

Kinetic and mechanistic insights into the atmospheric hydrogen abstraction of 3-Hydroxybutanal by chlorine

Keywords

Atmospheric reaction
Reaction pathway
Vibrational frequencies
Transition state
Kinetics and Thermodynamic parameters

Subjects

Chemical Review and Letters
Volume 9, Issue 1 - Serial Number 1
January and February 2026
Pages 11-16

  • Receive Date 03 July 2025
  • Revise Date 01 September 2025
  • Accept Date 11 October 2025

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