GB463711A - Improvements in or relating to the manufacture of amines - Google Patents

Abstract

Amines are prepared from primary, secondary or tertiary aliphatic alcohols containing 10--20 carbon atoms, or from alicyclic alcohols, by treating the alcohols in the vapour phase with ammonia in the presence of a dehydrating catalyst. The relative proportions of primary, secondary and tertiary amines produced may be controlled by adding one or two of these types of amines to the reaction mixture. Specified catalysts are alumina, thoria, tungsten oxide, metal sulphates and phosphates, silica gel, and zeolites; a description is given of the preparation of granular alumina, for use as a catalyst, from solutions of alum and sodium carbonate. Preferably, rigid supports impregnated with a dehydrating oxide or mixture of oxides are used. The supports may be impregnated, with or without preliminary evacuation, with a solution of a metal salt, such as a carbonate or nitrate, capable of yielding a dehydrating oxide when decomposed by heat. Specified supports are alumina gel, silica gel, active carbon, indianaite, base-exchanging silicates, and the material known under the Registered Trade Mark "Doucil." The reaction temperature may be 250--500 DEG C., preferably 300--400 DEG C., and the molar ratio alcohol: ammonia may vary between 1 : 0,25 and 1 : 10, but is preferably 1 : 3. The reaction may be effected at atmospheric or raised pressure. In the examples: (1) lauryl alcohol and ammonia are passed at 300 DEG C. and atmospheric pressure over a catalyst prepared by evacuating silica gel at 400 DEG C., impregnating the cooled gel in aluminium nitrate solution, and heating the product to 400 DEG C.; a mixture of mono-, di- and tri-laurylamines is obtained; (2) the process of example 1 is effected at 350 DEG C.; if mono- and tri-laurylamine are added to the reaction mixture, dilaurylamine only is produced; (3) stearyl alcohol and ammonia, passed at 360 DEG C. and atmospheric pressure over the catalyst of example 1, yield a mixture of mono-, di- and tri-stearylamines; (4) oleyl alcohol and ammonia, under the conditions of example 3, yield a mixture of mono-, di- and tri-oleylamines; (5) decamethylene glycol and ammonia are passed at 350 DEG C. and atmospheric pressure over the catalyst of example 1 and yield the corresponding diamine. Reference is made also to the manufacture of amines from cyclohexanol and naphthenyl alcohols.