Why 1,4-dioxane is a water-structure breaker

Computations performed for single and paired 1,4-dioxane molecules situated in vacuum and in water showed that the chair conformation is the most stable one. A pair of 1,4-dioxane rings forms a dimer, which is stabilized by two intermolecular hydrogen bonds. Two remaining oxygen atoms are available for interaction with the water molecules. The dimer retains the transfer from vacuum into water, although it results in significant distortion of the rings in terms of the bond distances and, particularly bond angles. The extent of distortion for both rings is different. In consequence, a fairly irregularly shaped bulk dimer exhibited a dipole moment. Such solute species could produce significant disorder of the water structure. Three 1,4-dioxane molecules in the chair conformation, under vacuum and in water, formed a trimer of differently distorted rings. The trimer was also energetically stabilized. Dioxane behaves similarly in nonaqueous, nonpolar and polar solutions. Stabilization energy and dipole moment was independent of the solvent polarity.