SOLUBILIZATION OF N-ALKYLBENZENES INTO 1-DODECANESULFONIC ACID MICELLES

The solubilization of benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-peptylbenzene into 1-dodecanesulfonic acid was measured. Concentrations of all the substrates in equilibrium were det ermined spectrophotometrically at 293.15, 298.15, 303.15, and 308.15 K . The first stepwise association constants ((K) over bar(1)) between s olubilizate monomer and vacant micelle were evaluated from the equilib rium concentration and were found to increase with hydrophobicity of t he solubilizate molecules. They were 1.31 x 10(3), 3.28 x 10(3), 9.64 x 10(3), 2.96 x 10(4), 9.52 x 10(4), and 3.95 x 10(5) mol(-1) dm(3) at 298.15 K for benzene, toluene, ethylbenzene, n-propylbenzene, n-butyl benzene, and n-pentylbenzene, respectively. The standard Gibbs energy, enthalpy, and entropy changes in this system were compared with those for solubilizations of polycyclic aromatic compounds and of p-n-alkyl benzoic acids to thermodynamically study the solubilized state of the solubilizates.