We report a simple, inexpensive, visual, and environmentally friendly S_N2 reaction appropriate for the second-year organic chemistry laboratory that illustrates stereospecificity, dependence of water solubility on the state of ionization, optical activity, and effect of diastereotopic protons in ¹H NMR spectroscopy. The reaction converts readily available l-phenylalanine in a double S_N2 reaction to enantiomerically pure (S)-2-hydroxy-3-phenylpropanoic acid. The optical purity and absolute stereochemistry are determined by the specific rotation of the product.

中文翻译：

---

l-苯丙氨酸向（S）-2-羟基-3-苯基丙酸的转化：立体特异性S _N 2反应的简单直观示例

我们报告了一种简单，便宜，可视且对环境友好的S _N 2反应，适用于第二年的有机化学实验室，该反应说明了立体定向性，水溶性对电离状态的依赖性，光学活性以及非对映质子在¹ H中的作用NMR光谱。该反应在双S _N 2反应中将容易获得的1-苯丙氨酸转化为对映体纯的（S）-2-羟基-3-苯基丙酸。光学纯度和绝对立体化学取决于产物的比旋度。