School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
Department of Chemical and Biochemical Engineering, Western University, London, ON N6A 5B9, Canada.
Molecules. 2018 Dec 18;23(12):3354. doi: 10.3390/molecules23123354.
In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter: PEA), which is soluble in water, ()-(+)-benzyl-1-phenylethylamine (()-(+)-BPA) was used to resolve 4-chloromandelic acid (4-ClMA) in this study. The optimal resolution conditions were determined: absolute ethanol as a solvent, the molar ratio of 4-ClMA to ()-(+)-BPA as 1:1, the filtration temperature as 15 °C, and the amount of solvent as 1.6 mL/1 mmol 4-ClMA. Thermophysical properties, such as melting point, heat of fusion, and solubility, exhibited significant differences between the less and more soluble salts. The single crystals for the pair of diastereomeric salts were cultivated and their crystal structures were examined thoroughly. In addition to commonly observed interactions like hydrogen bonding and CH/π interactions. The chlorine…chlorine interaction was observed in the less soluble salt presenting as Cl…Cl between adjacent hydrogen network columns, while the Cl/π interaction was observed in the more soluble salt. It was found that halogen interactions played an important role in chiral recognition of 4-ClMA by ()-(+)-BPA.
为避免常用拆分剂 1-苯乙胺（简称：PEA）溶于水的缺点，本研究采用 ()-(+)-苄基-1-苯乙胺（()-(+)-BPA）拆分 4-氯扁桃酸（4-ClMA）。确定了最佳拆分条件：以无水乙醇为溶剂，4-ClMA 与 ()-(+)-BPA 的摩尔比为 1:1，过滤温度为 15°C，溶剂用量为 1.6mL/1mmol 4-ClMA。在较难溶解的盐和较易溶解的盐之间，表现出熔点、熔融热和溶解度等热物理性质的显著差异。培养了该对非对映异构体盐的单晶，并对其晶体结构进行了详细研究。除了常见的氢键和 CH/π 相互作用外，在较难溶解的盐中还观察到氯…氯相互作用，表现为相邻氢网络列之间的 Cl…Cl 相互作用，而在较易溶解的盐中则观察到 Cl/π 相互作用。研究发现，卤原子相互作用在 ()-(+)-BPA 对 4-ClMA 的手性识别中起着重要作用。
