Solubilization of n-alkylbenzenes into lithium 1-perfluoroundecanoate micelles

The solubilization of benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, n-pentylbenzene, n-hexylbenzene, and some arenes into lithium 1-perfluoroundecanoate micelles was measured with increasing the surfactant concentration. Concentrations of all the solubilizates in equilibrium were determined spectrophotometrically at 293.2, 298.2, 303.2, and 308.2 K. The concentration of benzene, toluene, naphthalene, anthracene, and pyrene was not found to increase under the same condition. The first stepwise association constants ((K) over bar(1)) between solubilizate monomer and vacant micelle were evaluated from the equilibrium concentration of solubilizate and were found to increase with increasing hydrophobicity of the solubilizate molecules for the alkylbenzenes. The thermodynamic parameters in this system were compared with those for solubilization into 1-dodecanesulfonic acid micelles. These solubilizates were all solubilized on the surface region of the fluorocarbon micelles, which is different from the previous result that the solubilizates with longer alkyl chains were in the inner part of the above-mentioned hydrocarbon micelles. (C) 1998 Academic Press.