Thermodynamic properties of the benzene-phenol dimer in dilute aqueous solution

Precise vapor pressure-solubility measurements have been obtained for dilute solutions of benzene and phenol in water at 15, 25, 35 and 45°C. All of the results are consistent with a mass action model that attributes deviations from ideal solution behavior to the formation of benzene dimers and hetero-dimers between benzene and phenol. The benzene-phenol dimer forms endothermically at 25°C, with a very large negative heat capacity, and a formation constant that reaches a maximum value of 0.66 l-mol^?1 at approximately 35°C. Thermodynamic properties of the benzene-phenol dimer are reported and compared with those of other aggregates that are believed to be stabilized primarily by hydrophobic interactions.