Practical synthesis of (6-chloro-3-pyridyl)methylamine by highly selective hydrogenation of 6-chloro-3-pyridinecarbonitrile with improved Raney nickel catalyst

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 degrees 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 degrees 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.