Abstract
Micellar solubilization of barbiturates by polyoxyethylene lauryl ether was investigated by the methods of solubility measurement, equilibrium and dynamic dialyses, potentiometric titration and molecular sieve. Amount of solubilized barbiturate was found to be proportional to free concentration in aqueous phase. Evaluating volume fraction of micelle, partition coefficient between aqueous and micellar phases, K, was used as the quantitative indication of micellar solubilization. Results obtained by various methods were in good agreement. Phenobarbital alone showed specific interaction with polyoxyethylene lauryl ether in solubility study at temperature below 45°. To see the effect of chemical structure on solubilization attempt was made to subdivide log K into terms concerning Taft's substituent constant, carbon number of substituents and unsubstituted barbituric acid. These considerations suggest that major portion of barbiturate is localized in polyoxyethylene layer of micelle.
