Mechanism of the formation of secondary and tertiary amines in the course of the catalytic hydrogenation of adiponitrile to 1,6-hexanediamine

1. Among the products of the hydrogenation of adiponitrile the following previously undescribed compounds containing a tertiary nitrogen atom were isolated: 1-(6-aminohexyl)hexamethylenimine, 1,1′-hexamethylenebis (hexamethylenimine), and hexahydro-1-azepinehexanenitrile. 2. Under the optimum conditions for the hydrogenation of adiponitrile to 1,6-hexanediamine (temperature 80–100°, initial hydrogen pressure 100 atm), the primary and primary-secondary amines formed do n of under-go any change. 3. In the process investigated, the amines containing a secondary or tertiary nitrogen atom are formed n of by deamination, but by the aldimine mechanism: reaction of the intermediately formed 6-iminohexylamine with 1,6-hexanediamine to give 6,6′-iminobishexylamine, and its reaction with hexamethylenimine to give 1-(6-aminohexyl) hexamethylenimine.