GB436214A - Improvements in the manufacture and production of amines - Google Patents

Abstract

Amines are prepared from aldehydes or ketones by treatment with hydrogen and ammonia at a raised temperature and pressure in the presence of a catalyst comprising an oxygen-containing or sulphur-containing compound of a heavy metal which is practically not reduced to metal under the working conditions. Amines are prepared also from oximes, or from compounds of the type of Schiff's bases derived from aldehydes or ketones by condensation with primary amines, by treatment with hydrogen at a raised temperature and pressure in the presence of a catalyst as defined above, but in the presence or absence of ammonia. Specified catalysts are (a) oxides of metals of the sixth periodic group and sulphides of metals of the sixth and eighth periodic groups, including tungsten oxide, molybdenum oxide, tungsten disulphide, molybdenum disulphide, and mixtures of sulphides of tungsten and (or) molybdenum with sulphides of iron, cobalt or nickel; (b) salts of tungstic acid and (or) molybdic acid, e.g. the alkali or alkaline earth salts; (c) complex compounds of these acids, e.g. their reaction products with chromium trioxide or chromium oxide, or phosphotungstic or phosphomolybdic acid; the catalysts may be mixed with small proportions of activating substances, e.g. sodium hydroxide, calcium oxide or barium oxide; carriers such as pumice stone, aluminium oxide or aluminium silicate may be employed; binding agents such as china clay or zinc phosphate (useful also as a catalyst) may be present. Specified starting materials are acetaldehyde, hexylaldehyde, isohexylaldehyde, cetyl aldehyde, cinnamic aldehyde, acetone, dipropyl ketone, octadecyl methyl ketone and their oximes, and lauric aldehyde. The reaction is preferably effected at 200--400 DEG C. under a pressure of more than 50 atm. The waste gases from the synthesis of ammonia, or the circulating gas used therein, may be used as the source of hydrogen. In the examples, (1) acetone, ammonia and hydrogen are passed at 320 DEG C. and 200 atm. pressure over nickel sulphotungstate; mono- and di-isopropylamine are obtained; acetone oxime may be converted similarly into the same products; (2) isohexylaldehyde (2-methylpentenal), ammonia and hydrogen are brought to reaction as in example 1; mono- and di-isohexylamine are obtained; isohexylaldehyde oxime may be similarly treated. Specifications 304,640, [Class 2 (iii)], 365,214; and 412,914 (as open to inspection under Sect. 91) are referred to.