CS208783B2 - Method of making the n-alkylarylamines - Google Patents

Abstract

1. Process for the production of N-alkylaryl amines by reacting aryl amines with alkanoles in the gaseous phase at temperatures from between 180 to 450 degrees C in the presence of catalysts, characterized in starting from arylamine having the formula see diagramm : EP0006590,P4,F3 wherein R1 is a hydrogen atom or an alkyl radical having from 1-4 carbon atoms, R2 is a hydrogen atom, a cyano or nitro group, a halogen atom or an alkyl, alkoxy or methyl alkoxy radical having up to 4 carbon atoms, and n is 1 or 2, and under the proviso that n = 1, R2 may also be a phenyl radical or a group having the formula see diagramm : EP0006590,P4,F4 wherein R3 is an alkylene or alkylidene radical having up to 3 carbon atoms, R4 is a hydrogen atom or a alkyl radical having from 1-4 carbon atoms, together with alkanols having from 1-4 carbon atoms in a molar ratio of from 0.5 to 1-20, using as catalyst copper deposited on silicate support.

Description

The invention relates to a process for the preparation of N-alkylairylamines, in particular to the preparation of N-moncalkylarylamines.

N alkylalarms are compounds of formula I

wherein n is 0, 1 or 2,

R 1 represents a hydrogen atom or a C 1 -C 4 alkyl radical,

R2 represents a hydrogen atom, a halogen atom, a C1-C4 alkyl radical, a C1-C4 alkoxy radical, a cyano group or a nitro group, and if n is 1, R2 may also represent a phenyl radical or a radical of formula in which:

R3 represents an alkylene radical or an alkylidene radical having 2 to 3 carbon atoms,

R 4 represents a hydrogen atom or a C 1 -C 4 alkyl radical, and

R 5 represents an alkyl radical having 1 to 4 carbon atoms.

It is known to produce N-alkyl larynons by reacting arylamines with alcohols. As -C- catalysts used are aluminum oxide or křemičltany (DE Patent ^sp: 693 417, DE Patent No. 638756). These catalysts have the disadvantage that their activity decreases rapidly and thus the service life is reduced. Carriers containing phosphorus oxyacids or salts thereof have also been used as catalysts (DE patent 617 990). Also these catalysts have only a short lifetime. DAS 2 335 906 discloses catalysts consisting of silicic acid having a surface area of 50 to 500 m ² / g and containing 0.1 to 20% by weight of phosphoric acid. In this case, phosphoric acid or an alkyl ester of phosphoric acid is continuously fed to the catalyst during the reaction. The disadvantage of this process is that the presence of phosphoric acid, even if only small amounts thereof, causes great problems due to the corrosion of the overall reactor system. Furthermore, the selectivity of the catalyst with

20878 3 with respect to the production of only N-monoalkylarylamines is imperfect.

According to the process of the invention, N-alkylarylamines are prepared by reacting arylamines of formula II

n, Ri. And R2 are as defined above, with the alkanols of formula III

RsOH (III) wherein

R 5 is as defined above, in a molar ratio of 0.5 to 1 to 20, and the supported catalyst is copper supported on a silicate support or supported copper oxide.

The catalyst according to the invention preferably has a specific surface area of 10 to 100 m ² / g, preferably 12 to 25 m 2 / g. Preferably, the catalyst is used in a fixed bed. In this case, shaped, for example in the form of cubes or spheres, is used. Depending on whether N-monoalkylarylamines or Nd erykylarylamines are to be obtained, the arylamine / alkanol ratio may vary from 0.5 to 1 to 20.

The process according to the invention is particularly suitable for the preparation of Nwuo alkylarylamines. In this case, 0.5 to 2, preferably 1 to 1.2, mol of alkanol is used for 1 mole of arylamine.

Preferably, the aromatic amines are derived from benzene - and have one amino group. In addition to the amino group, preferred aromatic amines may contain 1 or 2 substituents inert under the reaction conditions, such as alkyl radicals having 1 to 4 carbon atoms, alkoxy radicals having 1 to 4 carbon atoms, cyano groups or nitro groups, further halogen atoms. or methylalkoxy radicals. Aniline, toluidines or xylidines are particularly preferably used as starting materials. Suitable amines are, for example, neither lin, o-toluidine, m-toluidine, p-toluidine, xylidines, anisidines, halogenated anilines in the core, or m-nitraniline and p-nitraniline, furthermore 4,4‘-diamino-aminomethylme.

Preferred alkanols are (C 1 -C 4) alkanols, such as. methanol, ethanol, propanol, isopropanols or butanols. Methanol or ethanol are particularly important.

The reaction is carried out at a temperature of 180 to 450 ° C. Particularly good results are obtained at temperatures of 220 to 350 ° C. Generally, the reaction is carried out at atmospheric pressure. Slightly increased pressure is also possible, for example up to 10.105 Pa. Further, the temperature and pressure conditions are selected so that the reaction can be carried out in the gas phase. Moreover, it turned out to be. It is preferable to use together with carrier gases which are inert under the reaction conditions, such as nitrogen.

The process according to the invention is preferably carried out by:. the catalyst is introduced into a fixed bed reactor, heated to the reaction temperature, and a mixture of arylamino and alkanol is introduced over a short time period, for example 4 to 100 seconds. The gaseous reaction mixture is condensed, the organic layer is separated from the aqueous layer and the desired alkylarylamine is isolated from the organic layer.

Example 1

200 parts by weight of catalyst are added to an electrically heated fixed bed reactor (26 mm, length 700 mm). The catalyst in the form of spheres or spheres consists of copper on a silicate support.

The catalyst is maintained at 250 ° C and 29.4 pbw of ntihayol-ailine (1: 1 molar ratio) is pumped per hour.

The residence time in the catalyst bed is 42 s.

The gaseous reaction mixture obtained is condensed. Per hour . 26.7 parts by weight of condensate are obtained, which is separated into an aqueous and an organic layer. The organic layer contains 21.4 wt. parts by weight of N-methylaniline, 0.2 parts by weight of N, N-dimethylaniline, 3 parts by weight of aniline and 0.2 parts by weight of methanol. This corresponds to 86% aniline conversion. The yield of N-methylaniline, based on the reacted aniline, was 97.7%.

Examples 2 to 5

Arylamide Alkanol Molar ratio Catalyst g Temperature Noc: 2 ° C Conversion ° / o Monoprod. % + Diprod. % + 2. Anilin N-butanol 1 - 1 155 230 72.8 80.4 - 3. пИпЕтШи ethanol 1: 1,2 200 280 80.6 85.4 - 4. Anilin n-propanol 1 - 1 155 250 71.8 81.7 0.6 5. Xyltdin methanol 1: 1.5 125 230 58.6 97.4 -

+ Based on conversion

Example 6

In an electrically heated fixed bed reactor (0 26 mm, length 700 mm), 200 g of a catalyst consisting of CuO supported on a carrier - kaolin-water glass (34 proc. Cu) are charged and maintained at a temperature of 220 to 330 ° C. C. The xylidine-methanol mixture (molar ratio 0.67 to 1) is pumped in over a 42 second time delay. The result is a 49.1% yield of the corresponding mono product at 49.9% conversion.

Example 7

The procedure was as in Example 1 except that an aniline-methanol molar ratio of 0.5 to 18 was used. The conversion was 85.4 percent and the yield of N-methylaniline was 81 percent.

Claims (3)

OBJECT OF THE INVENTION A process for the preparation of an N-C ^H ^ y ^ ll ^ (a) aryl amyl of the general formula I (I) in which n is 0, 1 or 2, R1 represents a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, R2 represents a hydrogen atom, a halogen atom, an alkyl radical having from 1 to 4 carbon atoms, an alkoxy radical having from 1 to 4 carbon atoms, a cyano group or a nitro group, and if n is 1, R2 may also represent a phenyl radical or radical R 3 represents an alkylene radical or an alkylidene radical having 2 to 3 carbon atoms, R 4 represents a hydrogen atom or a C 1 -C 4 -alkyl radical, and R5 denotes an alkyl radical having from 1 to 4 carbon atoms, by reacting arylamines with alkanols in the gas phase at temperatures of 180 to 450 DEG C. in the presence of catalysts, characterized in that they are reacted with arylamines of the formula II Rf NH (I) in which n, R1 and R2 are as defined above, with the alkanols of formula III R 5 OH (III) wherein R 5 is as defined above, in a molar ratio of 0.5 to 1 to 20, and the supported catalyst is copper supported on a silicate support or supported copper oxide. 2. Process according to claim 1, characterized in that a catalyst having a specific surface area of 10 to 100 m @ ² / g is used. 3. A process according to any one of claims 1 to 3, wherein the catalyst comprises copper or copper oxide deposited on a kaolin-water glass support.