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The partition equilibria of a series of thirty substituted phenols bearing different chemical groups between aqueous solutions and sodium dodecylsulfate micelles was investigated by using micellar high-performance liquid chromatography and by studying the variation of the acidity constant. The contribution of each substituent to the free energy of transfer from water to micelles was estimated. The group contribution approach is shown to be valid for polysubstituted compounds under well defined conditions. A comparison with partition coefficients obtained in classical two-phase system (1-octanol/water), frequently used as biochemical model systems, is discussed

The formation of the ground state charge transfer complex between durene and chloranil has been investigated in CH 2 Cl 2 and in microemulsions. The CH 2 Cl 2 or CH 2 Cl 2 /hexadecane microemulsion systems in water are stabilized by a cationic (hexadecyltrimethylammonium bromide) surfactant and 1-butanol as cosurfactant; the droplets have an average radius of 3.5 ± 0.5 nm. If the effective concentration in the oil phase (CH 2 Cl 2 or CH 2 Cl 2 /hexadecane) is accounted for, the equilibrium constant is not significantly changed with respect to the homogeneous CH 2 Cl 2 solution. The equilibrium of formation or dissociation of the complex is reached in less than 1 × 10 −3 s.