Relative Humidity and Altitude Effects on the Water-Mediated Hydrogen Abstraction Reaction of Furan by the Hydroxyl Radical

Despite the relevance of furanic compounds as atmospheric pollutants, the role of the water molecule in their oxidation mechanisms still needs to be comprehended. Here, we present new insights into furan's water-mediated hydrogen abstraction mechanism by the OH radical and its atmospheric implications. Compared to the naked mechanism, the addition of the water monomer increases the chemical complexity, yielding three and six pathways for the hydrogen abstraction on the alpha and beta carbons, respectively. Employing the pre-equilibrium model, we calculate the termolecular rate constants and then estimate the effective reaction rate as a function of the relative humidity. Our results suggest that the effect of water on the hydrogen abstraction rate is negligible. In addition, we also determined that the reaction rate at the stratosphere is 5 orders of magnitude slower compared to the troposphere.