Separation and purification of optically active substancc by crystallization

对DL-扁桃酸水溶液进行了实验研究，采用常压冷却法，考察了L-扁桃酸对DL-酸的溶解度数据，溶解度数据小于30%。高压结晶法测得L-扁桃酸在此范围内的溶解度曲线均大于30%。从这些观察到的数据，一个新的有效的光学拆分过程之间的蒸发和高压结晶的组合提出。研究了在等电点和过饱和溶液中，L-羧甲基-L-半胱氨酸（S-Carboxymethyl-L-Cysteine，L-SCMC）从DL-SCMC溶液中的光学拆分，讨论了L-SCMC种子生长时D-SCMC晶核不成核的情况。在过饱和度为0.1-0.25 [g/100 ml]的DL-SCMC水溶液中，用5%和10%（重量）的NaCl溶液，观察到L-SCMC单晶的晶体生长速率。实验结果表明，溶液中D-SCMC浓度对L-SCMC晶体生长速率有影响，并提出了由L-SCMC过饱和度与S-D之比定义的干扰因子α。另一方面，在刚加入L-SCMC晶种后的操作初期，由于加入过饱和溶液中的L-SCMC晶种的生长，溶液中仅L-SCMC的浓度降低，但当操作持续较长时间时，D-SCMC的浓度也开始降低。证实了这一现象是由于D-SCMC晶核在L-SCMC粒子表面成核所致。研究了D-SCMC二维成核的等待时间，发现溶液过饱和度和晶体悬浮密度对D-SCMC二维成核的等待时间有影响。从这些数据中找出了仅生长L-SCMC晶体的操作条件。采用蒸发结晶法观察了L-SCMC晶种的晶体生长速率，并与冷却结晶法进行了比较。

Experimental study of aqueous solution of DL-Mandelic acid was carried out to observe solubility data less than 30 percent of L-Mandelic acid against DL-acid by the cooling method under atmospheric pressure. And the solubility curve for the range was more than 30 percent of L-Mandelic acid also observed by high pressure crystallization. From this observed data, a new effective optical resolution process was proposed as a combination between evaporation and high pressure crystallization. And optical resolution of L-SCMC (S-Carboxymethyl-L-Cysteine) from DL-SCMC solution was studied at isoelectric point and supersaturated solution in which L-SCMC seed grew without nucleation of D-SCMC nuclei, was discussed. Crystal growth rate of a single crystal of L-SCMC was observed in aqueous solution of DL-SCMC with 5 and 10 wt% of NaCl for the range of supersaturation of 0.1-0.25 [g/100ml]. From these test's results, crystal growth rate of L-SCMC was affected by concentration D-SCMC "S_D" factor in the solution and disturb factor alpha which was defined by the ratio of supersaturation of L-SCMC to S_D, was proposed. On the other hand, concentration of only L-SCMC in the solution decreased by growth of L-SCMC seed which was added into supersaturated solution, for an initial period of operation just after L-SCMC seed was added, but when the operation continued for a long while, concentration of D-SCMC also started to decrease. This phenomenon was confirmed to come from nucleation of D-SCMC nuclei on the surface of L-SCMC aeed. Then, this nucleation was studied, and waiting time for two-dimensional nucleation of D-SCMC turned out to be affected by supersaturation of the solution and suspension density of crystal in the solution. Operational condition on which only L-SCMC crystal grows, was found out from this data. And crystal growth rate of L-SCMC seed was also observed by evaporatting crystallization and the data was compared with data obtained by cooling crystallization.