DD146178A5 - PROCESS FOR THE PREPARATION OF 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

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-a- 21390

Process for the preparation of N-alkylarylamines

Field of application of the invention:

Me invention relates to a process for the preparation of N-alkylarylamines <>

Characteristic of the known technical solutions :.

It is known to prepare bi-alkylarylamines by reacting arylamines with alkanols. As catalysts, for example, alumina or silicates are used (DE-PS 693 417o DE-PS 638 756). These catalysts have the disadvantage that their activity decreases rapidly and thus the life is very limited _o There have already been used as catalysts carriers which have a content of oxygen acids of phosphorus or salts thereof (DP bl7 990) _o Such catalysts have only a short life. From the DAS 2,335,906 are

Catalysts are known, which consist of silica having an inner surface of 50 to 500 m / g and a content of 0.1 to 20 % of phosphoric acid. During the reaction, the catalyst is continuously fed with phosphoric acid or alkyl phosphates. The part of this process is that the presence of phosphoric acid, even if it is only a small amount, causes great corrosion problems in the entire reactor system. In addition, the selectivity of the catalyst with respect to the production of only H-monoalkylarylamines leaves something to be desired.

The aim of the present invention was to find a technically simple process for the preparation of Itf-alkylarylamines, in particular for the preparation of N-monoalkylarylamines, starting from arylamines and the corresponding alkanols.

According to the invention, this is achieved by using a catalyst consisting of copper deposited on a silicate support. The catalyst may consist of metallic copper deposited on the siliceous support or of copper oxide supported on the support. Preferably, the catalyst has a specific surface area of from 10 to 100 m / g.

2 zv / eckmäßig 12 to 25 m / g.

Advantageously, the catalyst is applied in the plague bed. At the same time it comes to being shaped, eg "B. in cubic or spherical form, for use.

Depending on whether H-monoalkylarylamines or N-dialkylarylamines are to be obtained in the main, the molar ratio of arylamine / alkanol may vary from 0.5 to 1 to 1 to 20. The process of the invention is advantageously suitable for the preparation of N-monoarylamines. Preferably used aromatic amines of the formula

in which R 1 is a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, R _{2 is} a hydrogen atom, a cyano or nitro group or an alkyl or alkoxy radical having up to 4 carbon atoms and η is 1 or 2 and, if N = 1, R _{2 is} also a phenyl radical or the radical of the formula

-R-

can stand in which R ,, is an alkylene or alkylidene radical having up to 4 carbon atoms and R ^ can denote a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms.

Preference is given to aromatic amines which are derived from benzene and have an amino group. In addition to the amino group, the preferred aromatic amines 1

or 2 substituents inert under reaction conditions, such as alkyl radicals having 1 to 4 carbon atoms, alkoxy radicals having 1 to 4 carbon atoms,. Aniline, toluidines or xylidines are particularly preferably used as starting materials. Suitable amines are, for example, aniline, o-toluidine, m-toluidine, p-toluidine, xylidines, anisidines, ring-halogenated anilines or m-toluidines. and p-nitraniline, further 4,4'-diaminodiphenylmethane.

Preferred alkanols are those having 1 to 4 carbon atoms, such as methanol, ethanol, propanol, isopropanols or butanols. "Of particular importance has methanol or ethanol obtained

The reaction is carried out at a temperature of 180 to 450 G. Particularly good results are obtained. Temperatures of 220 to 35O ⁰ O. In general, the reaction is carried out at llomraldruck. It is also possible to use slightly elevated pressure, Z ₀ B apply bar up to 10 ₀ "Further, the temperature and pressure conditions are chosen so that the reaction in the gas phase can be carried out _e Additionally, it has proved advantageous, carrier gases, which are inert under the reaction conditions, such as nitrogen, to be used.

The process of the invention is advantageously carried out so that the catalyst is introduced into a pest bed reactor, heated to reaction temperature and the mixture arylamine / alkanol is introduced during a short residence time, for example _o 4 to 100 see. 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.

- ⁵ - 213900

Examples: Example .. 1

In an electrically heated fixed bed reactor (0 26 mm, length 700 mm) 200 parts by weight of catalyst were added. The catalyst in cubic or spherical form consists of copper on a silicate carrier.

The catalyst was kept at 25O ⁰ C and hourly 29.4 parts by weight of a mixture of methanol / aniline zugepumpto (molar ratio 1 to 1)

The residence time in the catalyst bed was 42 seconds.

The resulting gaseous reaction mixture was condensed. There were obtained hourly 26.7 parts by weight of condensate, which separated into an aqueous and organic layer. The organic layer contained 21.4 weight-. parts of N-methylaniline, 0.2 parts by weight of Ν, Ν-dimethylaniline, 3 parts by weight of aniline and 0.2 parts by weight of methanol. This corresponds to aniline conversion of 86%. The yield of N-methylaniline, based on reacted aniline, was 97.7 %.

Example 2 to 5

Aralamid Alkanol Molver-iKatälyt Tempe Revenues Monodi

ratio P * "od. P ^ ⁰ ^ ·

2. Aniline N-Butanol 1: 1 155 230

3. m-Toluidine ethanol 1: 1.2 200 280

4. Aniline n-propanol 1: 1 155 250

5. Xylidine methanol 1: 1.5 125 230

⁺ based on sales

72.8 80.4 - 80.6 85.4 - 71.8 81.7 0, -6 58.6 97.4 -

Claims (3)

Erfindunp; sanspruch 1. A process for the preparation of N-Alkylarylamineη by reacting arylamines with alkanols in the gas phase "at temperatures of 180 to 400 ⁰ C in the presence of catalysts, characterized by reacting arylamines with alkanols in a molar ratio of 0.5 to 1 to 1 : 20 used and used as a catalyst applied copper on silicate carrier. 2., Process according to item 1, characterized in that one uses a catalyst having a specific surface area of 10 to 100 in ² / g. 3. The method according to item 1 and 2, characterized in that one uses a catalyst consisting of copper or copper oxide, applied to a kaolin water glass carrier, «