TRANSITION OF SHORT-RANGE TO MEDIUM-RANGE ORDER IN AQUEOUS-SOLUTION OF 2-BUTOXYETHANOL

The change in the mixing scheme in aqueous solutions of 2-butoxyethanol (BE) and tert-butyl alcohol (TBA) can be regarded as the transition of a short/medium-range order and is associated with anomalies in quantities proportional to third derivatives of the free energy. While softening of this kind of transition is apparent from the temperature dependence of the partial molar heat capacity (a third derivative of the free energy), that of the solute-solute interaction in terms of enthalpy in the BE-H2O system, ∂HmE(BE)/∂nBE(another third derivative), did not show an apparent softening. © 1990 American Chemical Society.