DE637730C - Process for the preparation of N-alkyl derivatives of ammonia - Google Patents

Description

It is known that ammonia and primary or secondary amines can be obtained by treatment convert with aliphatic alcohols in the presence of dehydrating catalysts into N-alkyl derivatives of ammonia can. However, the reaction products obtained are often very inconsistent, see above that difficulties arise in the work-up, and when using alcohols higher than methanol, moreover, occurs easily a considerable decomposition of the alcohols due to splitting off of another Water molecule with the formation of ethylene or other olefins. For these reasons, this procedure has for the Implementation with alcohols higher than methanol gain no practical significance can.

It has now been found that one can use N-alkyl derivatives of ammonia can advantageously be prepared by adding ammonia or primary or secondary amines in the presence Dehydrating catalysts at elevated temperature and under elevated pressure

treated with ethers containing at least one alkyl group with two or more carbon atoms contain. It has been shown that when these ethers are used, instead of the corresponding higher alcohols, the Al-

kylation is much faster and smoother; lower temperatures can be used here and shorter response times can be used. Olefin formation also becomes significant degraded.

The reaction temperatures are generally between about 150 and 450 °, expediently between 200 and 400 °. It is generally beneficial when printing 10 at or more to work. This significantly suppresses the formation of olefins, so that you can work at higher temperatures without the undesired formation of To increase olefins considerably; this is particularly difficult when processing alkylatable amines of advantage.

Particularly suitable catalysts are aluminum oxide gel, peptized or conventional Aluminum oxide, thoroxide, cerium oxide, silica gel or their mixtures.

It has been found to be beneficial, especially when following the circulatory process works, the undesired decomposition products that may occur, z. B. olefins, to be added to the reaction mixture or to be allowed to accumulate in it. Through this Measure, the olefin formation can be restricted even further.

For the present method, not only symmetrical, but also mixed ones can be used Ethers can be used which have an alkyl group with at least two carbon atoms contain. The other can do this

*) The patent seeker indicated the following as the inventors:

Dr. Leonid Andrussow in Mannheim and Dr. Emil Germann in Ludwigshafen a. Rh.

Hydrocarbon group belong either to the aliphatic or to the aromatic series. When used purely aliphatic mixed ether in ₄ generally mixtures of the alkyl ether desv corresponding alkyl derivatives arise. ' ^l /

The technical progress achieved by the present process is. therein ■ to; see that it has now become possible - to produce ₁₀ in a simple manner such N-alkyl derivatives of ammonia ,, in which the alkyl group contains two or more carbon atoms. Up to now one has often had to struggle with difficulties in the preparation of such derivatives, even in cases where the preparation of the corresponding N-methyl derivatives is easy. is to be carried out. For example, N-diethylaniline can only be obtained with poor yields from aniline and ethyl alcohol with sulfuric acid, although N-dimethylaniline is obtained very easily and smoothly from methanol in an analogous manner. One is therefore forced to work in the production of N-diethylaniline using a ₅ hydrochloric acid, which causes a great risk of corrosion and correspondingly high costs. According to the present process, however, it is easy to produce low-cost diethylaniline.

It is already known to treat ammonia, primary or secondary amines in the presence of dehydrating catalysts at elevated temperature with dimethyl ether. However, the dimethyl ether behaves "differently from the ethers of higher alcohols as they are used in the present process. While with dimethyl ether it makes no difference whether one works with or without the use of overpressure," the higher ethers decompose through the action the dehydrating. Catalysts very easily at ordinary pressure, especially with the formation of olefins and waters, what. substantial losses Ver ^1. conditional on ethers and also the

■ · Has the disadvantage that the water formed is the

Counteracts alkylation of the amines. It could be due to the familiar way of working not anticipated that ethers containing at least one alkyl group with two or

'Have more carbon atoms can be reacted very advantageously with ammonia or amines to form higher molecular weight amines.

However, this is the case as a result of the application of increased pressure, as this

■ generation of. Ethylene or other olefins the ethers used are largely avoided. For example, if a mixture of 30 moles of aniline and 70 moles of diethyl ether at 290 ° with -einer. Flow velocity from 401 steam mixture per hour over 100 ecm aluminum oxide gel conducts, about 20 to 23% ethylene, based on the amount of ether consumed. • '■ • ESttrch is the application of increased pressures ; jg.6er 'the olefin formation to a low level ^ deducted. It is thus possible to -washed amines in very good yield win what could not be achieved before when working without pressure.

. -. example 1

25 kg mol of aniline and 75 kg mol of diethyl ether are passed every hour over 11 peptized aluminum oxide at 150 atmospheres pressure and 320 °. About one third of the product obtained consists of monoethylaniline and two thirds of diethylaniline. The Äthylenbildung is only 4 to 7 ° / ₀ · If you give to the starting mixture i2 ° / o ethylene added, the Äthylenbildung drops to under 3%> related to the used amount of ether.

Example 2

40 moles of monoethylaniline and 60 moles of diethyl ether are treated as in Example 1. A diethylaniline is obtained which contains only about ι ο% monoethylaniline.

Example '3

ι g-mol of aniline and 4 g-mol of diethyl ether are passed at 320 ⁰ over 600 ecm.peptisiert aluminum oxide under a pressure of 20 at. An amine mixture is obtained which consists of 1.5% aniline, 34.3% monoethylaniline and 64.2%. ° / ₀ consists of diethylaniline.,

Example 4

o-Toluidine and dibutyl ether are under 25 at pressure at 325 ° in an amount of 54 g of o-toluidine and 100 g of dibutyl ether per hour over 100 ecm of peptized aluminum oxide directed. After the excess ether has been distilled off, an amine mixture is obtained, which contains 18.9% o-toluidine, 75% monobutyl and 6, i ° / o dibutyl-o-toluidine.

Example 5

A mixture of aniline and dibutyl ether is under 30 at pressure at 325 ° in a Amount of 93 g aniline and 195 g dibutyl ether per hour peptized over 200 ecm Aluminum oxide is obtained after distilling off the unreacted Ether is an amine mixture with the following composition: 79.4% monobutylaniline, 5> 3% dibutylaniline and 5.3% aniline.

Instead of peptized aluminum oxide, thorium oxide can also be used as a catalyst use. An amine mixture of similar composition is obtained in this way.

Example 6

Aniline and ethyl butyl ether are together at 330 ° under 20 at pressure 200 ecm of peptized aluminum oxide passed, with the proportions chosen be that per hour 93 g of aniline and 112 g of ethyl butyl ether over the catalyst stream. An amine mixture is obtained which consists of io, o ° / o primary, 59.8% secondary and 30.2% of tertiary base.

Example 7

Is introduced at 350 ⁰ under 22 atm pressure per hour a mixture of 1 g-moles of ammonia and diethyl ether over 200 cc alumina and supplies the gaseous reaction mixture in "sulfuric acid. There is obtained a solution of sulfuric acid Äthylaminen based on 100 parts by weight of the free Base contains 13.2 parts by weight of ammonia, 50.6 parts by weight of monoethylamine, 28.3 parts by weight of diethylamine and 7 parts by weight of triethylamine.

If the mixture of free bases obtained therefrom is treated in the same way, as stated above, again with diethyl ether, you get a base mixture, which has a higher content of diethylamine.

Example, 8

Passing per hour a mixture of ι g-mole of aniline and 4 g-mole of diethyl ether at 350 ⁰ at 20 under pressure over 200 cc of a Aluminiumoxydkatalysators. The unused ether is removed by distillation from the reaction product, and so one obtains a mixture of bases, which consists of 35.5% ^of mono- and 64.5% of diethylaniline and which can be easily separated in a distillation column. By changing the quantitative ratio of ether to aniline and setting appropriate reaction temperatures, the two bases can be obtained in the respectively desired quantitative ratio.

Claims (2)

Patent claims: 1. Process for the preparation of N-alkyl derivatives of ammonia, characterized in that ammonia or primary or secondary amines are present in the presence Dehydrating catalysts treated with ethers at elevated temperature and pressure, which contain at least one alkyl group having two or more carbon atoms. 2. The method according to claim 1, characterized in that one is in the presence of olefins works.