文摘
In this paper, the solubility of methyl D-(−)-4-hydroxy-phenylglycinate was measured under the different pH levels, pure solvents, mixed solvents, ionic strength, and impurities in the temperature range from 283 to 323 about 5 K intervals by using laser method at atmospheric pressure. The results reveal that the solubility of methyl D-(−)-4-hydroxy-phenylglycinate increases with increasing temperature in all selected solvents, which decreases with increasing mole fraction composition of water in the mixed solvents. The solubility curve of methyl D-(−)-4-hydroxy-phenylglycinate in the aqueous solution at different pH is “U” shape and the solubility of methyl D-(−)-4-hydroxy-phenylglycinate increases with concentrations of ammonium chloride and has no obvious changes when its concentration increases up to 1.25 mol/kg. It is beneficial to maximize the reaction conversion rate of D-4-hydroxyphenylglycine methyl ester hydrochloride and reduce the residual D-4-hydroxyphenylglycine methyl ester hydrochloride on reactive crystallization of methyl D-(−)-4-hydroxy-phenylglycinate. Furthermore, the modified Apelblat equation and CT = C0(αH+/k1 + k2/αH+ + 1) type correlation regression model have made good correlation of the experimental solubility in pure solvents, mixed solvents, and the aqueous solution at different pH, respectively.