The Properties of Water of Crystallization of Sodium Prasterone Sulfate

抄録

The properties of water of crystallization of sodium prasterone sulfate (DHA·SO₃Na·2H₂O) were investigated by thermometric measurements. The anhydrous form (DHA·SO₃Na) was very hygroscopic, and easily transformed to the dihydrate. The dihydrate was in a stable phase under ordinary storage conditions. If the released water molecules were not effectively exhausted in the dehydration process, a liquefaction phenomenon due to the interaction between water molecules and DHA·SO₃Na was observed. The activation energy (ΔE) of the dehydration reaction from the dihydrate to the anhydrous form was determined by an isothermal method and a non-isothermal method (Ozawa method) under a constant water vapor pressure, P_H2O=14.9 mmHg. ΔE obtained by the isothermal method was 31.5 kcal/mol and ΔE obtained by the Ozawa method was 31.3 kcal/mol.