To investigate the thermodynamic and molecular self-assembly mechanism of trans-1,2-cyclohexane dicarboxylic acid containing two carboxylic acid groups in the chiral resolution process, (S)-phenylethylamine was used as the chiral resolving agent. Two stoichiometric salts were formed when the raw materials were fed at different molar ratios: cyclohexane dicarboxylate monophenylethylamine salt and cyclohexane dicarboxylate diphenylethylamine salt. When the molar ratio of the (S)-phenylethylamine to trans-1,2-cyclohexane dicarboxylic acid was less than 3:1, trans-(1S,2S)-cyclohexane dicarboxylic acid was obtained with 97 e.e% purity. But when the molar ratio exceeded 3:1, the product was the racemic trans-(1,2)-cyclohexane dicarboxylic acid. In addition, single crystal structures of more soluble mono-salt, less soluble mono-salt, and less soluble di-salt were obtained. The weak intermolecular interactions and the way of the molecules packing in the crystals were analyzed. The hydrogen bond was stronger in the less soluble salt than that in the more soluble salt. And a “lock-and-key” structure in the hydrophobic layers makes it more tightly packed through the van der Waals interaction, which is responsible for the stability of less soluble salts.

中文翻译：

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基于进料摩尔比控制形成非对映体盐拆分含两个羧基的反式1,2-环己烷二甲酸

为了研究含两个羧酸基团的反式-1,2-环己烷二甲酸在手性拆分过程中的热力学和分子自组装机理，采用( S )-苯乙胺作为手性拆分剂。当原料以不同摩尔比加入时，形成两种化学计量盐：环己烷二羧酸一苯乙胺盐和环己烷二羧酸二苯乙胺盐。当( S )-苯乙胺与反式-1,2-环己烷二甲酸的摩尔比小于3:1时，得到纯度为97ee%的反式-( 1S,2S )-环己烷二甲酸。但当摩尔比超过3:1时，产物为外消旋的反式-(1,2)-环己烷二甲酸。此外，还获得了溶解度较高的单盐、溶解度较小的单盐和溶解度较小的二盐的单晶结构。分析了晶体中弱的分子间相互作用和分子堆积方式。难溶性盐中的氢键强于易溶性盐中的氢键。疏水层中的“锁和钥匙”结构使其通过范德华相互作用更加紧密地堆积，这导致了难溶盐的稳定性。