DE2121325C2 - Process for the preparation of methoxypropionitrile - Google Patents

Description

The invention relates to the production of Methoxypropionätri! according to the preceding claim.

The addition of compounds containing alcoholic hydroxyl groups to acrylonitrile under the The action of strong alkalis is known as the cyanoethylation reaction and provides cyanoethyl ether alcohols concerned.

An important cyano ethyl ether is methoxypropionitrile, which can be converted to methoxypropylamine by reduction with hydrogen; Methoxypropylamine is used industrially as a component for the production of herbicides and acid aniides and ionic emulsifiers and directly as a corrosion inhibitor.

Specifically, the addition of methanol to acrylonitrile, which, for example, from US Patents 29 71855 and 30 71 611 is known is generally in the presence of Sodium hydroxide or potassium hydroxide, optionally also in the presence of sodium methylate, carried out This method can be carried out in the laboratory in a satisfactory manner, since the after Reaction by neutralization with an acid now present as a sparingly soluble salt or sodium Potassium hydroxide can be filtered off.

However, the formation of larger amounts of salt is a must for implementation on an industrial process scale Disadvantage. The salts formed represent annoying by-products and also tend to be in the course of the process To create difficulties. Finally, the methoxypropionitrile yield is unsatisfactory.

If one neglects to neutralize the basic catalyst and instead in its presence the If the nitrite is hydrogenated to amine, considerable yield losses are observed. *

It has also already been described, the addition of acrylonitrile to alcohols in the presence of make quaternary ammonium bases. In particular, that is known under the trade name "Triton B" Trimethylbenzylate ammonium hydroxide has already been used as a catalyst, see US patent 23 26 721. However, the use of such a catalyst on an industrial scale is ruled out economic reasons, since it does not have the advantageous yields as the process according to the invention supplies.

Against the use of the catalyst used in the present process for the cyanoethylation There was considerable prejudice about methanol because it is known (cf. Bruson in Org. Reactions 5, 79 bis 135 (1949), especially page 93 above) that the action of acrylonitrile in the presence of bases on Triethanolamine leads to corresponding cyanoethylated products

s Surprisingly, however, this does not seem to be the case) if methyl alcohol is used as alcohol in sufficient concentration is available, since apparently the reaction of methyl alcohol with acrylonitrile after the claimed process extremely quickly

ίο runs

According to Ulimanns Enc. d. techn. Chemistry, 3rd ed., Volume 3, 1953, p. 101 arises from the action of ethylene oxide on triethanolamine under the usual technical Reaction conditions in a certain amount of tetraethanol ammonium hydroxide (= Tetrakis- (ß-hydroxyethylammonium hydroxide). It is assumed that the inventive effect of reaction products of triethanolamine with ethylene cide is based on the presence of this quaternary base -

A reaction mixture which can be used as a catalyst according to the invention and which contains the quaternary ammonium base in an amount of 0.5 to 50% is obtained, for example, when ethylene oxide and NH3 ^{are reacted with one another without catalysts at 50 to 150 °} C. in a continuous or discontinuous process The implementation takes place under the pressure of the starting components. The crude reaction mixture is then used directly as a catalyst without further purification or distillation. According to Ullmann loc. cit is formed in this reaction as an intermediate triethanolamine which continues to react with ethylene oxide

In any case, it was found that the mixture of the various ethanolamines used in the technical Reaction of ammonia with ethylene oxide is formed, and especially that in the distillation of the various alkanolamine bases remaining an extraordinarily high and very specific residue catalytic effect on the implementation of

Exercises acrylonitrile with methyl alcohol.

The success of the method according to the invention was also not foreseeable in so far as after J. Am. Chem. Soc 70, 3667/68 (1948) in the implementation unsaturated compounds with mercaptans, the »Triton-B« catalyst, the tetrakishydroxyethylammonium hydroxide is superior

In detail is to carry out the invention Method of saying the following: Regarding molar ratios, temperatures and others

such reaction conditions, the process according to the invention does not differ from the prior art. Thus, it is advantageous to react acrylonitrile and methanol in a molar ratio of 1 : 0.1 to 1: 1.3 at a reaction temperature in the range from 20 to 200 ° C, preferably 40 to 70 ° C, batchwise or continuously in the presence of the catalyst according to claim . You can work without a solvent or as a solvent z. B. use tetrahydrofuran, benzene or dioxane.

You can, for example, proceed so that methanol in a suitable reaction vessel, the z. B. a Rühfkessel can be, is presented, and in the course of a few hours the intended amount of acrylonitrile after and after is added. The catalytically active compound is z. B. in an amount of 0.05 to 15, expediently 0.2 to 0.8%, calculated as terakis hydroxyethyl ammonium hydroxide used.

The obtained by the method according to the invention

3 4

ne methoxypropionitrile can easily or 4370 kg of crude can be obtained from the filtrate

optionally also after a cleaning step, e.g. B. methoxypropionitrile as a brown homogeneous liquid,

after a distillation, can be further processed. To the _Ve "i -: _ h _c . _ra > h 11

Example can be obtained by hydrogenation with hydrogen in vergieicnsversucn 11 Presence of cobalt at a temperature of 20 to 5 The procedure is as described in Example Ib),

300 ⁰ C, in particular 50 to 100 ⁰ C, and at a pressure, however, used as a catalyst 17 parts of the below

between normal pressure and 500 atmospheres, expediently 100 to the trade name "Triton B" known trimethyl

250 atm, methoxypropionitrile by itself or in the presence of benzylammonium hydroxide. 4410 parts are obtained

an inert solvent, such as tetrahydrofu crude methoxypropionitrile in the form of a dark brown

ran, dioxane, diethyl ether, benzene or toluene, to ion a homogeneous liquid.

Hydrogenate methoxypropylamine. Hydrogenation of crude methoxypropionitrile to Example methoxypropylamine

a) For the production of a suitable catalyst Since methoxypropionitrile is because of its light weight a mixture of ethylene oxide and ammonia was not z. B. Purify by distillation If technical triethanolamine is not produced, it is used to assess the conversion of methanol customary technical reaction conditions (see and acrylonitrile required, the resulting methoxy-Ullmann loc. cit) with water and ethylene oxide propionitrile in crude form into a stable compound added, the molar ratio of triethanol convert to which the actually obtained yield amine to ethyl oxide <m reaction product 1: 1 20 can be determined. Since it is planned anyway fraud. Methoxypropionitrile for the production of methoxypro-

b) The hydrogenation to methoxy stainless steel is to be used in a pylamine stirred tank with a capacity of 5000 kg 1665 kg of methyl alcohol, 17 kg of propylamine are now a suitable method, the process soil to check the conversion productivity of the previous stage described above.

tes and 3 parts of hydroquinone as a stabilizer 25 It were therefore made in an autoclave

submitted Within 3 hours one leaves under stainless steel! those in the previous

good stirring 2730 kg of acrylonitrile run in, with experiments total amounts of reaction

by means of suitable cooling measures, each of the reactants is subjected to a hydrogenation,

tion temperature is kept at 50 to 55 ° C. The hydrogenation catalyst used is about

When the feed is complete, a post-30 4400 parts of crude methoxypropionitrile 25 parts of Raney

reaction period of about V ₂ to 1 hour. It uses cobalt activated with 1.5% chromium

4415 kg of methoxypropionitrile are easily The reaction is in the presence of 8800 parts

yellowish homogeneous liquid egg, old, without | _an ammonia run

Further cleaning measures for other reac- The hydrogenation is carried out with increasing temperature in the

can be used. 35 range from 50 to 100 ⁰ C and at a gradually

Comparative experiment I increasing hydrogen pressure from about 98 to 245 bar

carried out It is finished after about 4 hours.

In the manner described in Example Ib The liquid reaction mixture is over a fine

1665 kg of methyl alcohol in the presence of 34 kg of sieve from the autoclave and ammonia in

aqueous 50% sodium hydroxide solution and 3 kg Hydrochi- 40 driven off a column. The ammonia stands for that

non implemented with 2730kg acrylonitrile. Now next hydrogenation will be available again. the

carefully and gradually 20 kg of concentrated sulfur hydrogenation from the previous examples

acid added and the methoxypropylene obtained in solid form or comparative experiments

Sodium sulfate filtered off. The filters must have the nitrile levels in the table below

be cleaned several times. 45 result shown:

Tabel Yield% amine number Nitrile raw amine raw amine pure (Soll 628)

Example 4415 4645 4420 96 629

Compare Vers. I 4370 4579 3990 87 639 Cf. Vers. II 4411 4614 3 791 83 636

Claims (1)

Claim: A process for the preparation of methoxypropionitrile by reacting acrylonitrile and methanol in the presence of a quaternary ammonium base as a catalyst, characterized in that the catalyst used is the mixtures containing tetrakishydroxyethylammonium hydroxide obtained by the action of ethylene oxide on triethanolamine under customary technical reaction conditions, or mixtures containing those obtained by technical conversion of ammonia have been with ethylene oxide at 50- 150 ⁰ C in the absence of catalysts, if appropriate after distillation of the reaction product obtained.