Experimental results of positron annihilation experiments in solutions of n-butanol in three diols are compared to those of
ultrasonic velocity and absorption. Variations of the annihilation parameters with composition show that the effect of the
hydrophobic solute on the original diol structure is rather limited and occurs only in the system where ethylene glycol is
the solvent. Subtle similarities were found when compared it to the respective results for similar aqueous systems, suggesting
that crystalline-like solvates are forming in ethylene glycol. However, no such evidences were found for the systems where
butanediols are the solvents. Ultrasonic investigations do not confirm formation of any specific structures. This is caused,
most possibly, by the fact that compressibility of solvates is close to those of the pure components and/or that of unstructured
medium (regular solution).