The structure of a concentrated aqueous solution of tertiary butanol: Water pockets and resulting perturbations

The structure of a 0.86 mole fraction solution of tertiary butanol in water at room temperature has been investigated by neutron diffraction with hydrogen/deuterium isotope substitution. The intermolecular correlations between the alcohol and water molecules have been extracted using the empirical potential structure refinement technique. The results highlight the creation of water pockets within the solution structure. These pockets mediate the interactions that occur between the alcohol hydroxyl groups, reducing the level of direct alcohol-alcohol hydrogen bonding. The results show that only a small amount of water is required to drive this solution in the direction of hydrophobic behavior more commonly associated with the water-rich solution compositions. (C) 2002 American Institute of Physics.