Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Green leaf volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all four GLVs exhibit deep free energy minima at the air/water interfaces; the stability of the GLV solutes at the air/water interface is mainly driven by energetic interactions between these solutes and water molecules. Our results suggest that the air/water interface is the most likely site for chemical reactions between GLVs and atmospheric oxidants. Such a finding has important implications in the kinetics and mechanisms of these reactions, which can be significantly different from those observed when these reactions take place in the gas phase or in the bulk of water phases.