GB759291A - Improvements in or relating to the production of secondary amines - Google Patents

Abstract

Saturated aliphatic secondary amines are obtained by heating with a hydrogenation catalyst an aliphatic nitrile or a primary aliphatic amine of 8-22 carbon atoms (or mixture of such nitrile and amine) until all the moisture has been removed, contacting the mixture with hydrogen under pressure, maintaining within the hydrogenation zone the ammonia formed until the total amine content becomes constant, discharging the ammonia and continuing the hydrogenation to completion. Further ammonia may be discharged at intervals during the final hydrogenation. The entire process should be carried out in the absence of hydroxides and metallic soaps but the presence of an inert bleaching agent is desirable, e.g. 1-3 per cent of finely divided activated carbon or adsorbent clay. The preheating may be to 120-150 DEG C. and it is preferable to pass an inert gas through the mixture during this period. Suitable conditions for the initial hydrogenation are 130-160 DEG C. and 100-500 p.s.i.g., e.g. 135 DEG C. at 175-190 p.s.i.g. The catalyst may be Raney nickel in an amount of 0.4-3 per cent based on weight of nickel to weight of nitrile. The ammonia is discharged when the total amine content has ceased to rise, e.g. at about 75-90 per cent. The hydrogenation is then continued at a higher temperature such as 170-210 DEG C., preferably 175-198 DEG C. The starting materials may be the C12-C18 nitriles or amines obtained from natural fats and may be a mixture. When a double bond is present this is saturated during the hydrogenation. Examples are given of the process using the nitriles and amines derived from coconut and tallow fatty acids, the products containing some primary amine.