Crystallization of s-carboxymethyl-cysteine for its optical resolutic

从工业角度研究了L-SCMC(S-羧甲基-半胱氨酸)在氯化钠存在下的过饱和溶液中的结晶现象。重点讨论了在间歇结晶器中利用悬浮晶种对L-SCMC晶种的粘结现象和二次成核问题进行了讨论。在这些试验中，标记的种子晶体也被悬浮，并观察到晶体表面的细小颗粒群，结果如下：1)在间歇操作的初始阶段，悬浮在过饱和溶液中的细小颗粒数量几乎是恒定的。晶种表面几乎没有细小颗粒，但附着在晶种表面的细小颗粒数量随着晶种生长周期的延长而增加。在此条件下，种群的过饱和度不同，细粒数均为L-SCMC。通过对种子表面的观察，模拟了粉粒的滞留行为，并从理论上解释了观察到的悬浮粉粒群落率与粉粒粘附率之间的线性关系。当晶种表面积被微粉覆盖约50%时，微粉粘附量与生长周期的关系曲线偏离理论线。2)观察到d-SCMC粘附量。在L-SCMC种子出现d-SCMC粉粒的初期，d-SCMC粉粒滞留量随运行周期的4次方而增加。在种子表面观察到d-SCMC后1.5h，在悬浮细粉中观察到d-SCMC。在此基础上提出了d-SCMC的非均相成核模型，一般认为d-SCMC在工业结晶器中悬浮在过饱和溶液中，会影响产品晶体的生长速度和质量。在研究结晶器中生产所需晶体的优化设计时，细小颗粒在生长晶体上的粘连现象被认为是重要的。

Crystallization phenomena of l-SCMC(s-carboxymethyl-cysteine)in supersaturated solution of dl-SCMC in the presence of sodium chloride was studied from the point of view of industrial purpose. Especially, sticking phonomena of fines on l-SCMC seed crystal and secondary nucleation by it were focused and discussed by suspended seed crystal in a batch crystallizer. In these tests, the marked seed crystal was also suspended and populations of fines found on a crystal surface were also observed, following results were obtained.1)Population of fines suspended in supersaturated solution were almost constant for initial period of batch operation. On a surface of seed crystal, fines were hardly found, but population of fines stuck on seed increased with increase of growth period of seed crystal. On these conditions, population were different by degree of supersaturation and fines were of l-SCMC. From the observation of seed surface rharked, behavior of stuck fines were modeled, and linear correlation between population rate of suspended fines and sticking rate of fines, observed were explained theoretically. When surface area of seed crystal covered by fines became about fifty percents, plots between amount of stuck fines and growing period, became deviated from theoretical line.2)Amount of d-SCMC stuck on crystal surface were observed. For initial period that fines of d-SCMC appeared on l-SCMC seed, amount of stuck d-SCMC fines increased with fourth power of operating period. After 1.5 h after d-SCMC was observed on seed surface, d-SCMC was observed in the suspended fines. From this results, heterogeneous nucleation model of d-SCMC was proposed.Fines are generally considered to be suspended in a supersaturated solution in an industrial crystallizer and affect on growth rate and quality of product crystal. When optimum design for produce of desired crystal in a crystallizer is studied, sticking phenomena of fines on growing crystal is considered important.