L-丝氨酸在水溶液中的假多晶型行为

Pseudo-Polymorphic Behavior of L-Serine in Aqueous Solution

采用激光法测定了L-丝氨酸在水中的溶解度,结果表明,L-丝氨酸无水合晶体与水合晶体的晶型转变温度为309.14 K,高于此温度时,无水物晶体是稳定的,低于此温度时,水合物晶体是稳定的。利用PVM和FBRM对L-丝氨酸水溶液的冷却结晶过程和晶型转变现象进行的实时监测表明,在高温区析出的是棒状无水合L-丝氨酸晶体,当冷却至晶型转变温度以下时,棒状晶体逐渐转变为六角片状的水合晶体。该转变行为主要与在低温下L-丝氨酸和水分子的氢键作用而形成水合晶体有关。

The solubility of L-Serine in water was measured by laser method. The experimental results show that the transition temperature of the two morphologies of L-serine, anhydrous and monohydrate crystals, is 309.14 K, upon which the anhydrous crystal is stable, while under which the monohydrate crystal is stable. The cooling crystallization and the polymorphic transition processes of L-Serine in aqueous solution were real time monitored by PVM and FBRM. The results show that at a higher temperature, the anhydrous crystals form in club-shaped habit, while the temperature of the slurry was cooled under the polymorphic transition temperature, the club-shaped anhydrous crystals would translate to the hexagonal plate-shaped monohydrate crystals. This translation behavior related to the fact that the monohydrate crystal can form easily due to the hydrogen bonds between the moleculars of L-Serine and water at lower temperature.