Abstract:

DTA anal. was used to confirm evidence from x-ray diffraction studies for the existence of 1:1 mixed sitosterol-cholesterol crystals. The curve of m.p. against compn. has an inflection point at about 1:1 ratio. The DTA peaks for 1:1 mech. mixts. and for 1:1 mixed crystals are different with respect to symmetry and width. The curve of the heat of enthalpy against the compn. of crystals also changes indicating a change in entropy. This can be attributed to the difference between melting mixed crystals (high order) and solid soln. (low order). The soly. curve in the sitosterol-cholesterol-alc. system has also a region of inflection confirming the previous conclusion. [on SciFinder(R)]