DD214125A1 - PROCESS FOR PREPARING N- (BETA-CYANETHYL) ANILINE - Google Patents

Abstract

The invention includes an improved process for the preparation of N- (betta-cyanoethyl) -aniline, an intermediate product required especially in dye synthesis. The starting formanilide is known to be reacted with acrylonitrile in the presence of dilute sodium hydroxide solution, according to the invention for a safety-harmless, continuous process for N-formyl-N- (betta-cyanethyl) -aniline and from the latter the formyl radical according to the inventive method with dilute sodium hydroxide solution split off at temperatures of 25 to 60 degrees C.

Description

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VES Cheraiekorabinat Bitterfeld 2432

Process for the preparation of N- (β-cyanoethyl) aniline

Field of application of the invention

N- (beta-cyanoethyl) aniline ~ is a valuable intermediate which koarat especially in the Farbstoffsynthsse directly or after substitution of the existing at the secondary amino group Wasserstoffatoffis used.

characteristics the known technical solutions

For the preparation of N- (.beta.-cyanoethyl) -aniline, a number of methods are known - for example, the reaction of acrylonitrile in the presence of suitable catalysts - but in many cases have the disadvantage that the reaction proceeds only incomplete or very long reaction times are required. Another disadvantage of these known methods is that the poisonous heavy metal salts used as catalysts must be removed from the process water with expensive methods and systems.

Also known is the saponification of N- {S-cyanoethyl) -aniiins with acids or alkalis, which ultimately leads to N-phenyl-ß-alanine.

DS-PS 734 725 describes a process according to which formamides, for example fonaanilide, with acrylonitrile in the presence of alkaline catalysts can be converted into the corresponding formylaisino-β-propionitriles, from which then

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in accordance with DE-OS 1 963 010, the formyl radical is split off hydrolytically with acid and thus N- (β-cyanoethyl) -amino compounds are obtained in good yield. A disadvantage here is the safety risk, which is present on the one hand by the highly exothermic heat of reaction, on the other hand by the alkali-catalyzed polymerization tendency of the acrylonitrile.

Aim of the invention

The aim of the invention is to develop a process for the preparation of N- (S-cyanoethyl) -aniline which, starting from forraanilide, leads in fast and simple procedure while avoiding safety-related risks to a final product suitable for further reactions a miniraum of impurities without additional purification operations, such as ^ crystallization or distillation, is used in the dye synthesis.

Loan of the essence of the invention

The object of the invention is "to develop a process by which an improved and risk-free production of N- (S-gyanethyi) -aniline is made possible. The conversion of formanilide acrylonitrile proceeds expeditiously in the presence of a sufficiently large amount of catalyst in the form of a dilute sodium hydroxide solution of 5 to 35% by weight, so that the reaction process of the first stage of the reaction is continuously formed by simultaneous metering of the reaction partners can. This procedure also has the advantage that "there are always only small volumes of the reactants in the reaction part of the manufacturing conditions and thus no danger monsent can occur even with excess acrylonitrile applied." Furthermore, it was surprisingly found that the cleavage of the formyl radical in the second reaction stage in contrast to above procedure also in

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5 to 25% by weight of dilute sodium hydroxide solution, especially those containing 10% by weight, at temperatures of 25 to 60 ° C., preferably of 35 to 40 ° C., such that ß-cyanoethyl) -aniline comes in good yield. The method has erfindungsgeraäße thereby aan advantage that impurities such as they always mitentstehen during the acidic hydrolysis of the nitrile group by hydrolysis in a detectable magnitude, unexpected, or only occur in the end product in trace amounts. In addition, the neutralization of the sodium hydroxide solution used for the catalysis of the first reaction stage (cyanoethylation) is unnecessary since additional sodium hydroxide solution is added anyway for the saponification of the formyl group. The yield of β- (cyanoethyl) -aniline is more than 90 % of theory, calculated on fortnanilide used.

The invention is explained by the following example, without, however, wanting to limit it to *

Working Example

In a reactor with a capacity of about 25 ml, equipped with a heating mantle, stirrer, thermometer, filler neck and headrace, with the help of dosing pump within 24 hours simultaneously 242 g (2 mol) of molten 'Fonsanilid, 160 ml ( about 128 g, corresponding to 2.4 mol) of acrylonitrile and 104 ml of an approximately 20% sodium hydroxide solution is fed continuously while vigorously stirred. By Heizsnantei 60 G warm water is pumped; the reaction temperature is adjusted to ca, 63 C by the liberated heat. The continuously flowing product is passed over a column filled with glass bodies and collected in a collecting vessel, whereby it separates into two phases. The incurred after 2.5 hours reaction product with 1200 ml 10 wt .-% iger. Sodium hydroxide added and stirred vigorously at 40 ° C for hours, with the N- (ß ~ Cyanethyl) -aniline deposited in solid form. 3e according to purpose, this can be filtered off immediately or saan neutra-

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lisiert-erst.mit mineral acid and then isolated by cooling the product crystallized by filtration

But it can also be the resulting, neutralized © product above the melting point heated in liquid form separated from the aqueous phase ^,!

This results in 273 g of N- (ß-Cyanethyi) -aniline of melting point 50 to 52 ° C, which corresponds to a yield of 93.5 % of theory _ä calculated on the used forraanilide corresponds.

Claims (1)

- 5 - 2432 Erfindunqsanspruch OTii-t-VTi ιι τ aw w ιιπίίΐιΤιϋ'ιιΜ njiniii iim Ii ιλ m * r A process for Hsrstellung of N- (S «Cyan9thyl) aniline from Fonaänilid and acrylonitrile in the presence of from 5 to 35 GQW" ~% i "even hydroxide solution at Tarap ^ ratursn of 20 to 80 ° C for ₁ characterized in that in the first asr stuf © the reaction the. Preparation of the intermediate compound N-Forrayi ~ N- (S-cyanoethyl) -aniline continuously designed and in the second stage, the cleavage of Fonaylrestss roit 5 to 20 wt .-% sodium hydroxide solution b © i Tefnperatursn from 25 to 60 ° C is performed.