对羟基苯甘氨酸在水-丙酮-硫酸混合溶剂中的溶解度及介稳区

Measurement of Solubility and Metastable Zone Width of dl-p-hydroxyphenylglycine in Mixed Solvent of Water-Acetone-Sulfuric Acid

分别采用恒温溶解法和变温溶解法测定了对羟基苯甘氨酸在水-丙酮-硫酸混合溶剂中的溶解度曲线和超溶解度曲线,利用激光监视装置检测测定系统中晶体的消失和产生,实验温度范围约为303～323K.随着混合溶剂中水的增加,溶解度略有增加;酸度增加,溶解度有较大幅度的增加.用经验方程二次多项式关联溶解度与温度的关系,计算的溶解度和实验值符合良好.测得的超溶解度曲线与溶懈度曲线基本平行,介稳区宽度以最大过冷度表示约为1.5～2.4K,温度升高时介稳区宽度略有减少.溶剂中水含量或硫酸含量增加将使介稳区宽度变小;降低搅拌速度使介稳区明显变宽.实验结果可应用于优先结晶法拆分对羟基苯甘氨酸.

Using isothermal method and the polythermal method respectively, the solubility curve and supersolubility curve of dl-p-hydroxyphenylglycine in water-acetone-sulfuric acid mixed solvents were measured at 303 K to 325 K. The detection of crystals disappearance and appearance in the measured system was done by laser monitoring observation technique. It was found that the solubility increased slightly with water concentration increasing and increased significantly with sulfuric acid concentration increasing in mixed solvents. The measured solubility curve and supersolubility curve were almost parallel. The metastable zone width represented by maximum undercooling was about 1.2 K to 2.4 K, and it slightly decreased with increasing saturation temperature. Increasing sulfuric acid concentration or water concentration in solvents reduced metastable zone width. Decreasing stirring rate could enhance the zone width significantly. The experimental results could be applied to the optical resolution of dl-p-hydroxyphenylglycine by preferential crystallization procedure.