Solubilization of benzoic acid derivatives by polyoxyethylene lauryl ether.

Abstract

The solubilization of 34 benzoic acid derivatives by polyoxyethylene lauryl ether micelles was quantitatively studied by solubility measurement and equilibrium dialysis. The logarithms of partition coefficients (K) of solubilizates between aqueous and micellar phases were directly related to the logarithms of their partition coefficients between aqueous solution and n-octanol (Poetanol). The plots could be grouped in four parallel linear relationships, each of which was characterized by the intercept b value. When the b value is connected with the positional distribution of hydrophilicity of the palisade layer with reference to n-octanol water content, the physical meaning of the value is probably related to the site of incorporation of solutes within the polyoxyethylene mantle. The results show that benzoic acid derivatives examined are classified into dicarboxylic acids, nitro and cyano compounds, the majority of compounds, and salicylic acids group, which are located in order from the outer layer of the mantle toward the hydrocarbon core.