A practical synthesis of (6-chloro-3-pyridyl)methylamine (1), one of the key intermediates of neo-nicotinoid insecticides, by a highly selective hydrogenation of 6-chloro-3-pyridinecarbonitrile (4) is described. The use of an improved Raney nickel catalyst, prepared from an alloy of low nickel content (Ni 38%, Al 62%) and subjected to heat treatment in water (98 °C, 2 h) after leaching of aluminum, was highly effective for the selective hydrogenation of 4. The hydrogenation of 4 using this catalyst was carried out in EtOH-H2O [6 : 1 (v/v)] and NH3 at 50 °C and 1.2—1.4 kg cm-2 hydrogen pressure to give 1 in 86% yield and 3-pyridylmethylamine, a dechlorinated by-product, in 2% yield.
                                    本文描述了一种实用合成(6-
氯-3-
吡啶基)
甲胺(1)的方法,该化合物是
新烟碱类
杀虫剂的重要中间体,采用对6-
氯-3-
吡啶腈(4)进行高度选择性的加氢反应。使用改进的Raney
镍催化剂,该催化剂由低
镍含量合
金(
镍38%,铝62%)制备,并在浸出铝后在
水中进行热处理(98°C, 2小时),对4的选择性加氢反应非常有效。使用该催化剂对4进行加氢反应是在
乙醇-
水 [6:1 (v/v)] 和
氨气的条件下,于50°C和1.2—1.4 kg cm-2的
氢气压力下进行的,最终得到1的产率为86%,并生成脱
氯副产物3-
吡啶基
甲胺,产率为2%。