定义Definition
三氯化磷 PCl₃ 是无色发烟液体，沸点约 76 °C，分子为三角锥形，磷原子上有一对孤电子对。它遇水剧烈水解生成亚磷酸和氯化氢，在有机合成中用于把醇转化为氯代烃，与氯气反应生成 PCl₅。
Phosphorus trichloride, PCl₃, is a colourless fuming liquid boiling at about 76 °C. The molecule is trigonal pyramidal, with a lone pair on phosphorus. It hydrolyses vigorously in water to phosphonic (phosphorous) acid and hydrogen chloride, converts alcohols to chloroalkanes in organic synthesis, and reacts with chlorine to give PCl₅.
主要反应Main reactions
水解：PCl₃ + 3H₂O → H₃PO₃ + 3HCl；与醇：3ROH + PCl₃ → 3RCl + H₃PO₃（PBr₃ 同理用于制溴代烃）；与氯气：PCl₃ + Cl₂ ⇌ PCl₅。
Hydrolysis: PCl₃ + 3H₂O → H₃PO₃ + 3HCl. With alcohols: 3ROH + PCl₃ → 3RCl + H₃PO₃ (PBr₃ is used the same way for bromoalkanes). With chlorine: PCl₃ + Cl₂ ⇌ PCl₅.
结构Structure
磷周围有三个成键电子对和一对孤电子对，四个电子区域呈四面体排布，分子为三角锥形，Cl–P–Cl 键角约 100°，是极性分子。
Phosphorus has three bonding pairs and a lone pair, arranged tetrahedrally, so the molecule is trigonal pyramidal with Cl–P–Cl angles of about 100°, and it is polar.
化学性质Chemical properties
水解：PCl₃ + 3H₂O → H₃PO₃ + 3HCl
Hydrolysis: PCl₃ + 3H₂O → H₃PO₃ + 3HCl
与氯气反应：PCl₃ + Cl₂ → PCl₅
With chlorine: PCl₃ + Cl₂ → PCl₅