Patent GB-588256-A (GB)
Title: Improvements in or relating to manufacture of aliphatic amines
Filed: 1944-10-10
Abstract: Aliphatic amines are prepared by continuously passing a vapour phase mixture of ammonia, hydrogen and an open chain aliphatic primary or secondary alcohol over a metallic hydrogenation catalyst, for example, nickel or cobalt, at a temperature between 150 DEG  and 230 DEG  C.  Preferably, at least one mol. and desirably at least 4 mols. of hydrogen and between 2 and 5.5 mols. of ammonia are reacted with each mol. of alcohol.  Suitably, vapour streams of the alcohol, ammonia and hydrogen are mixed, preheated and passed through a reactor containing the catalyst after which the less volatile constituents in the reaction mixture are condensed out and the remaining ammonia and hydrogen mixed with a further quantity of alcohol and recirculated through the system.  Mono-, di- and tri-alkyl amines are formed, the ratios between the three being controllable by adjustment of the ratio of alcohol to ammonia and by recycling the amine or amines desired in a smaller ratio in the final mixture.  The process may be operated at pressures up to above 500 lbs.  In the preferred process, nickel is used as the catalyst with a temperature of between 180 DEG  and 210 DEG  C. while maintaining a sufficient space velocity to give a fairly high flow rate of reactants.  In examples: (1) ethanol, hydrogen and ammonia in the molar proportions 5.2, 46.1 and 29.6 are passed over reduced nickel at 159 DEG  C. with a space velocity of 2070 (litres of gas at N.T.P. per litre of catalyst per hour) to give mono-, di- and tri-ethylamines in yields of 27.4, 45.0 and 12.8 per cent respectively; (2) and (3) ethanol containing 5 per cent mixed ethylamines as denaturant is reacted similarly, the unreacted ammonia and hydrogen being recirculated so that the ratio of ethanol : ammonia : hydrogen is 1 : 2.5 : 4.9 and the space velocity 2460; (4) butanol, hydrogen and ammonia in the molar proportions of 61.1, 397 and 370 are reacted as in (1), at 181 DEG  C. and 2250 space velocity the yields of mono-, di- and tributylamines being over 91.6 per cent, while in a comparative experiment in which the hydrogen is replaced by nitrogen the product contains 45 per cent butyronitrile and reduced yields of butylamines; (5) butanol (229 lbs.) and ammonia (64.5 lbs.) are passed over pelleted nickel at 195 DEG  C. and 16 lbs. pressure without added hydrogen, the hydrogen resulting from initial formation of nitrile and unreacted ammonia being rapidly recirculated so that the hydrogen concentration soon exceeds the total alcohol and ammonia in contact with the catalyst giving a reactants ratio as above of 1 : 6.4 : 8.7, the respective yields of the butyl amines being mono- 39.0 per cent, di- 46.0 per cent and tri- 8.7 per cent and of the nitrile 2.8 per cent; (6) diethylcarbinol (6.7 mols.), ammonia (58.1 mols.) and hydrogen (34.3 mols.) are reacted as in (1) at 190 DEG  C. and 2340 space velocity yielding 3-aminopentane (65 per cent conversion), di-sec.-amylamine (5.6 per cent) and some diethyl ketone. Specifications 306,414, 334,579, [both in Class 2 (iii)], and 456,952, U.S.A.  Specification 1,982,985 and French Specification 687,398 are referred to.