HYDROGEN-BONDS BETWEEN CHOLESTEROL AND OXYGEN BASES - A THERMODYNAMIC STUDY

Using calorimetric and IR spectroscopic methods, the values of thermodynamic functions of (1 : 1) hydrogen-bond complex formation between cholesterol and some proton acceptors in CCl4 have been determined. The self-association of cholesterol in the solvent used was taken into account in calculations. The proton acceptors used are oxygen bases containing C-0, -O-, P-0 and S-0 groups. The values of DELTA(f)H were compared with those previously obtained for the pure bases. The enthalpy of hydrogen-bond complex formation of cholesterol is a linear function of Gutmann's donor number for all the proton acceptor compounds examined. Badger-Bauer' s relation {DELTA(f)H = f[DELTAnu(OH)]} is not satisfied as well as DELTA(f)H = f(DN) but it allows the prediction of values of enthalpy of complex formation between cholesterol and proton acceptors within +/- 1.5 kJ mol-1 limits.