GB425486A - Improvements in the manufacture and production of amines - Google Patents

Abstract

Secondary amines are converted into primary amines by reaction with ammonia at a raised temperature in the presence of a dehydrating catalyst. Under the same conditions, tertiary amines are converted into primary or secondary amines by reaction with ammonia or a primary amine or a mixture thereof. The reactions are preferably affected at 300--500 DEG C. in the vapour phase and at a raised pressure. Suitable catalysts are alumina, thoria, titanium dioxide, silica, kaolin, aluminium phosphate, oxides of tungsten and molybdenum, and active charcoal; metallic catalysts may also be used, but are less suitable. A small proportion of an alcohol or phenol may be present in the reaction mixture. In the examples: (1) trimethylamine and ammonia are passed at 380 DEG C. and 150 atm. pressure over alumina gel; a mixture of mono-, di- and tri-methylamines is obtained, and is separated by fractional distillation; (2) triethylamine and ammonia are passed at 390 DEG C. and 200 atm. pressure over alumina gel; the mixture of mono-, di- and tri-ethylamines obtained is separated by fractional distillation, first under pressure and then at atmospheric pressure; (3) N-dimethylaniline and ammonia are led at 400 DEG C. and 200 atm. pressure over alumina gel; a mixture of aniline with N-mono- and -di-methylaniline is obtained; (4) as in example (1), except that the reaction is effected at 390 DEG C. and atmospheric pressure; (5) dioctadecylamine and ammonia are led at 380 DEG C. and 200 atm. pressure over alumina gel and kaolin; a mixture of mono- and dioctadecylamines is obtained; (6) aniline and trimethylamine are passed at 380 DEG C. and 100 atm. pressure over aluminium oxide; mono- and dimethylamine and mono- and di-methylaniline are produced.