Structurally simple enantiopure thioureas were used as chiral solvating agent (CSA) for the rapid determination of enantiomeric purity of chiral carboxylic acids by ¹H NMR spectroscopy in the presence of DMAP. The formation of diasteromeric complexes between the enantiopure thiourea and carboxylate-DMAPH⁺ ion pair gave rise to well-resolved ¹H NMR signals of the enantiomers of carboxylic acids. Furthermore, thiourea S,S-1 was used to assign the absolute configuration of mandelic acid.

中文翻译：

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使用单一对映异构体硫脲作为手性溶剂化剂对羧酸进行对映异构

结构简单的对映纯硫脲用作手性溶剂化剂（CSA），用于在DMAP存在下通过¹ H NMR光谱快速测定手性羧酸的对映体纯度。对映体纯的硫脲和羧酸酯-DMAPH ⁺离子对之间的非对映体复合物的形成引起了羧酸对映体的良好分辨的¹ H NMR信号。此外，使用硫脲S，S-1来分配扁桃酸的绝对构型。