DYNAMIC AND STATIC ASPECTS OF SOLUBILIZATION OF NEUTRAL ARENES IN IONIC MICELLAR SOLUTIONS

The kinetics of solubilization and the solubilities of neutral arenes in ionic micellar systems have been measured using phosphorescence, fluorescence, and steady-state absorption techniques. The exit rates for the arenes naphthalene, biphenyl, and I-methylnaphthalene were measured using their phosphorescence as a monitor, and found to be >5Χ104s-1. The exit rate of I-bromonaphthalene, from NaLS micelles, was determined as 2.5Χ104s-1. For this molecule the entrance rate was measured as 5-8Χ109M-1s-1, which can be considered a representative value for other arenes. Distribution constants between arenes and micelles have been measured both at low and saturation probe to micelle ratios. The distribution constants obtained at the different probe to micelle ratios are in approximate agreement, indicating that the arenes are dispersed among the micelles consistent with a Poisson distribution. An empirical model for the solubilization process is presented which incorporates the “site” of solubilization of the arene and the factors which govern the exit and entrance rates from the micelle. © 1979, American Chemical Society. All rights reserved.