INTERACTIONS BETWEEN CHOLESTEROL AND 2-METHOXYETHANOL - THE EFFECT OF2-METHOXYETHANOL AND OTHER HYDROXYLIC COMPOUNDS ON CHOLESTEROL - PROTON ACCEPTOR ASSOCIATION

Using the 'pure base' calorimetric method, the association enthalpy (D elta(f)H) of cholesterol and 2-methoxyethanol (MeOEtOH), triethylamine (TEA) or tri-1-butylamine (TEA) in the presence of MeOEtOH (10% mol) has been determined. The addition of 2-methoxyethanol to the amine bri ngs about the same effect as the addition of other simple alcohols (me thanol, butan-1-ol). The increase in the association enthalpy of chole sterol and TEA in the presence of MeOEtOH can be caused by MeOEtOH hyd roxyl group involved in the formation of mixed associates. Tn the case of amine with a weak steric hindrance (TEA), such an effect is not ob served. The addition of 10 mol% of water or alcohols to N,N-dimethylfo rmamide (DMF) makes no significant change in the cholesterol-DMF assoc iation enthalpy. This would suggest that the hydroxyl groups of added R'OH fail to participate in the formation of cholesterol-DMF associate s. A slight increase in Delta(f)H, taking place when water is added to DMF, can be attributed to an increased solvation of the associates be ing formed.