Binding of 2-naphtholate ions to a water-in-oil cetyltrimethylammonium bromide microemulsion. The enthalpy and entropy of interaction

Abstract

The binding of 2-naphtholate ions by a water-in-oil cetyltrimethylammonium microemulsion has been studied by u.v.–vis. spectroscopy. By assuming non-cooperative multiple equilibria in which the complexes obey Poisson's distribution law, the binding constants for the reaction were determined as a function of temperature. The reaction was found to be essentially enthalpy driven. Furthermore, it was observed that the entropy of reaction was small and positive below 25 °C. These thermodynamic parameters suggest that the binding involves both hydrophobic and electrostatic interactions.