Structural correlations of water molecules in a concentrated alcohol solution

Abstract

Hydrogen/deuterium isotopic substitution neutron scattering techniques andempirical potential structure refinement have been used to investigate thestructure in a 0.86 mole fraction solution of tertiary butanol in water. Theresulting model structure suggests that in this mixture, the relatively smallquantity of water molecules tend to associate in small hydrogen bonded clusters oftwo or three molecules, solvated by the alcohol hydroxyl groups. An interestingobservation on investigating this novel local water environment is that thetetrahedral hydrogen bonding motif of water still strongly influences thelocation of both the water and alcohol first neighbours. The combinationof the small number of water molecules in the mixture and the bulkymolecular structure of the alcohol appears to result in the incompletesatisfaction of the water molecule’s full hydrogen bonding capabilities.