Hexamethylenediamine: Adiponitrile Hydrogenated with Ammonia over Nickel, Howk 1939

Adiponitrile stirred with liquid ammonia and nickel under 1500–2000 lb/in² of hydrogen at 120 °C takes up hydrogen and becomes hexamethylenediamine (Howk, du Pont, US 2,166,151, 1939: 7500 g gave 6990 g). The ammonia keeps unwanted polymeric amines from forming. The diamine is the other half of nylon 66. The picture: our diagram of the autoclave run.