Haloalkanes play an important role in the atmosphere as a source of organic halogens. They are known to participate in heterogeneous chemistry, however, information about the exact reaction mechanisms is often missing. Using molecular dynamics simulations, we investigated interactions of haloalkane molecules with water surface. A systematic study included chloro-, bromo-, and iodoalkanes, from methyl halides (CH_3X) up to pentyl halides (C_5H_11X), where X = Cl, Br, or I. The results provide molecular level insight into the hydration shell structure and preferred alignment of haloalkane molecules on water. While most haloalkane species align parallel to the surface, with the hydrocarbon chain pointing slightly to the gas phase, methyl halide molecules orient themselves with the methyl group toward the aqueous phase and the halide atom exposed to the gas phase. This is likely to have consequences for reactivity of haloalkanes adsorbed on aqueous atmospheric particle surfaces.

Alkyl halides at the air–water interface: Surface residence and orientation

244th National Meeting (2012)

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