Molecular organization of liquid n-octanol: an X-ray diffraction analysis.

We recorded X-ray diffraction patterns from n-octane, n-octanol, and fully hydrated n-octanol. These patterns were analyzed using a modified version of the Percus-Yevick hard-sphere theory for liquids. A model is presented for the molecular organization of n-octanol that accurately predicts the observed diffraction patterns. The octanol molecules are associated in aggregates, with their hydroxyl groups forming roughly spherical clusters and their hydrocarbon chains pointing outwards, almost fully extended. When n-octanol is hydrated, the overall organization does not change greatly, but water molecules coordinate the hydroxyl groups in the clusters. Estimates are made for the maximum number of octanol molecules in the aggregates.