Abstract
The osmotic pressure of dilute aqueous solutions of a cyclodextrin and an alcohol were measured separately and in combination by the freezing point depression method with a commercially available osmometer. The results could be classified into two categories; in one, the osmotic pressure of combined solutes was equal to the sum of the individual values obtained seprately. In the other case, such additivity was not maintained. In the latter case, it was assumed that the two substances form a complex. On the basis of this assumption, stability constants for inclusion complexes of cyclodextrin with a variety of alcohols were determined. The stability constants obtained here were in fair agreement with those obtained previously by other methods. Therefore, it was concluded that measurement of freezing point depression is a useful method for determination of the stability constants for complex formation in an aqueous solution. The advantages and disadvantages of this method are discussed.
