HYDROGEN-BONDS OF CHOLESTEROL WITH SOME ANIONS IN CARBON-TETRACHLORIDE AND DICHLOROMETHANE

Using FT-IR spectrophotometry and calorimetry, the equilibrium constan ts (K-f) and enthalpies (Delta(f)H) of hydrogen bond complex formation (1:1) between cholesterol and anions have been determined. Some anion s such as Rr(-), Cl-, OCN- and MeCO2- of tetra-n-butylammonium salts w ere used as proton accepters. The process of complex formation: NBu4+X - + HO-chol = NBu4+-... HO-chol was examined in carbon tetrachloride a nd dichloromethane. The values of K-f and Delta(f)H of complex formati on in carbon tetrachloride increase for the mentioned actions in the f ollowing order: Bi- < Cl- < OCN- < MeCO2-, analogously as their hydrog en bond basicity. In dichloromethane the sequence is similar except fo r MeCO2- for which K-f, Delta(f)H and Delta(f)S are lower than expecte d. This can be due to the specific solvation of acetate anion in this solvent.