Formation of inclusion complexes of cyclodextrin with ethanol under anhydrous conditions

Complex formation of poorly water soluble organic compounds with cyclodextr in (CD) is quite difficult in an aqueous cyclodextrin system. Formation of the inclusion complex of d-limonene, phenyl ethanol, acetophenone, or menth ol was investigated in a slurry form of alpha-, beta-, or gamma-CD in organ ic solvents or alcohol under anhydrous conditions. Ethanol and methanol wer e found to be good solvents for this method. The use of ethanol as the solv ent was investigated in greater detail. There existed an optimal amount of ethanol for the maximum inclusion of d-limonene as the guest compound. Howe ver, an excess of ethanol inhibited the inclusion. An adsorption model of a lcohol on CD, analogous to the substrate inhibition model of enzyme kinetic s, could correlate the inclusion ratio with the amount of alcohol added to CD.