Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1997-10-28
1998-11-24
Burn, Brian M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
564399, 564415, C07C20922
Patent
active
058409815
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for preparing N-methyl-2-(3,4-dimethoxyphenyl)ethylamine (N-methylhomoveratrylamine) by reacting 3,4-dimethoxyphenylacetonitrile (veratryl cyanide) with a methylamine or substituted methylamine, where the substituent is a group which can be eliminated under the reaction conditions, and hydrogen in the presence of a supported catalyst which comprises copper chromite, an element of group IB or VIII of the Periodic Table of the Elements or mixtures thereof, in the presence or absence of water at elevated temperatures.
DE-A-33 38 681 discloses the catalytic hydrogenation of veratryl cyanide with a ten-fold molar excess of methylamine on a nickel catalyst. Homoveratrylamine is obtained as byproduct with more than 3% selectivity and has to be removed by adding benzaldehyde.
Arch. Pharm., 271 (1933) 431-448 discloses the hydrogenation of veratryl cyanide to N-methylhomoveratrylamine in the presence of methylamine and palladium black as catalyst. However, the yield is unsatisfactory in terms of the palladium employed.
Ind. Eng. Chem. Prod. Res. Dev., 6 (1967) 142-144 discloses the catalytic hydrogenation of nitriles to primary, secondary and tertiary amines on palladium and platinum catalysts, primarily leading to tertiary amines. Methanol is described as catalyst poison therein. Rhodium is said to be suitable for preparing secondary amines.
By contrast, the hydrogenation of valeronitrile with butylamine on palladium and platinum leads to butylpentylamine, but the conversions are low at 54% and 23% respectively.
Catalysis of Organic Reactions, (1992), 93-104 advises against the use of acidic catalysts such as titanium oxide or alumina, and the use of polar solvents in general and of methanol in particular, in the preparation of secondary amines from nitrites and primary amines.
It is an object of the present invention to remedy the abovementioned disadvantages.
We have found that this object is achieved by a novel and improved process for preparing N-methyl-2-(3,4-dimethoxyphenyl)ethylamine, which comprises hydrogenating 3,4-dimethoxyphenylacetonitrile with a methylamine of the general formula I ##STR2## where R.sup.1 is hydrogen, benzyl or tert-butyl, and hydrogen in the presence of a catalyst which comprises from 0.05 to 50% by weight of copper chromite, copper, silver, gold, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum or mixtures thereof, in the presence or absence of water at from 50.degree. to 200.degree. C. under from 1 to 300 bar.
The process according to the invention can be carried out in the following way:
3,4-dimethoxyphenylacetonitrile with a methylamine I and hydrogen can be reacted with from 0 to 30, preferably 0.05 to 2.5, particularly preferably 0.1 to 2%, by weight of water in the presence of a supported catalyst which comprises copper chromite, an element of group IB or VIII of the Periodic Table of the Elements or mixtures thereof, batchwise or continuously, preferably in a pressure vessel or reactor, such as an autoclave or tubular reactor, particularly preferably continuously in a tubular reactor, at from 20.degree. to 200.degree. C., preferably 50.degree. to 180.degree. C., particularly preferably 70.degree. to 160.degree. C., under from 1 to 300 bar, preferably 30 to 300 bar, particularly preferably 50 to 270 bar, with or without addition of a solvent. Working up can take place by conventional methods, for example by distillation.
Suitable methylamines I are in particular methylamine itself and those substituted methylamines I whose substituent is a group which can be eliminated under the reaction conditions, such as benzyl and tert-butyl, ie. benzylmethylamine and tert-butylmethylamine, preferably benzylmethylamine.
The benzyl or tert-butyl group can preferably be eliminated under the hydrogenation conditions, thermally or in the presence of inorganic or organic acids, such as sulfuric acid, hydrochloric acid, methylsulfonic acid or acetic acid, or acidic catalysts such as ion exchangers or zeolites.
The molar rat
REFERENCES:
Sogo Rikogaku Kenkyuka Hokoku (Kyushu Daigaku Daigakuin), 16(3) 307-10 (1994).
Archiv. Der Pharmazie, vol. 271, 1993, pp. 439-445, Kindler et al.
Becker Rainer
Breitscheidel Boris
Fuchs Eberhard
Nauhauser Horst
Witzel Tom
BASF - Aktiengesellschaft
Burn Brian M.
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