DEB0023245MA

DEB0023245MA -

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Publication number: DEB0023245MA
Authority: DE

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BUNDESREPUBLIK DEUTSCHLANDFEDERAL REPUBLIC OF GERMANY

Tag der Anmeldung: 6. Dezember 1952 Bekaiuitgeniacht am 11. Oktober 1956Registration day: December 6th, 1952

DEUTSCHES PATENTAMTGERMAN PATENT OFFICE

Es ist bekannt, Adipinsäuredinitril durch¹ Umsetzung von i, 4-Dichlorbutan mit Metall cyaniden herzustellen. Für die technische Ausführung dieser 'Reaktion hat man eine Reihe von Vorschlägen gemacht. It is known to adiponitrile by reaction of i ^1, 4-dichlorobutane cyanides produce with metal. A number of proposals have been made for the technical implementation of this reaction.

So soll man gemäß der französischen Patentschrift 898 118 das i, 4-Dichlorbutan bei 180 bis 200° auf eine Suspension von sorgfältig getrocknetem Natriumcyanid in fertigem Adipinsäuredinitril einwirken lassen. In der USA.-Patentschrift 2 222 302 wird beschrieben, daß man gleiche Mengen von 1, 4-Dichlorbutan und Methanol mit technischem Natriumcyanid in einem _ Druckgefäß 5 Stunden auf 150°-erhitzen soll.^: Bei 'dieser hohen Temperatur ist die bekannte Isomerisierung des 15 _ Adipinsäuredimtrils zum 2-Cyancyclopentanonimin begünstigt. Man hat deshalb vorgeschlagen, so zu arbeiten, daß höhere Temperaturen vermieden werden. Gemäß dem Verfahren der USA.-Patentschrift 2 415 261 läßt¹ man 1, 4-Dichlorbutan in einen siedenden Ätheralkohol, z. B. Glykolmonoäthyläther, einlaufen, in dem Natriumcyanid suspendiert ist. Hierbei wird die Reaktionswärme durch das siedende Verdünnungsmittel· abgeführt, und die Temperatur steigt nicht über dessen Siedepunkt, z.B. 125⁰. Der Zusatz von Wasser oder Methanol wird als unnötig, ja sogar ,als /unerwünscht bezeichnet,· weil dabei die Reaktionstemperaturen niedrigerThus, according to French patent specification 898 118, the 1,4-dichlorobutane should be allowed to act at 180 ° to 200 ° on a suspension of carefully dried sodium cyanide in finished adipic acid dinitrile. US Pat. No. 2,222,302 describes that equal amounts of 1,4-dichlorobutane and methanol with technical grade sodium cyanide should be heated to 150 ° for 5 hours in a pressure vessel. ^: At 'this high temperature, the known isomerization of 15-adipic acid dimtrile to 2-cyanocyclopentanoneimine is favored. It has therefore been proposed to work in such a way that higher temperatures are avoided. According to the method of USA. Patent 2,415,261 can be ^1, 1, 4-dichlorobutane in a boiling ether-alcohol, such. B. Glykolmonoäthyläther, in which sodium cyanide is suspended. The heat of reaction is dissipated by the boiling diluent and the temperature does not rise above its boiling point, for example 125 ^° . The addition of water or methanol is described as unnecessary, even as / undesirable, because the reaction temperatures are lower

609 657/471609 657/471

Claims

B 23245 IVb/12 οB 23245 IVb / 12 ο

and the reaction speed decreases. . In addition, they become disfigured as a result of, in part, hydrolysis of sodium cyanide and the longer

'■' ■ '■': duration of action for undesired by-products. The same applies to the procedure of the Italian patent specification -431407) in which the 1,4-dichloirbutane is to be refluxed with an aqueous-methanolic solution of sodium cyanide.

Following an earlier suggestion will be the cons avoided the process mentioned that one an aqueous alkali metal cyanide solution at about 80 to 100 ° into 1,4-dichlorobutane, expediently diluted with a glycol monoalkyl ether 'runs in.

It has been found that. it is even more advantageous to proceed in such a way that the 1, 4-you! or butane at temperatures between about 80 and 10 ° in a slurry of alkali or alkaline earth metal cyanide in a mixture of glycol monoalkyl ether and water, the ratio of i, 4-dichlorobutane to glycol monoalkyl ether about 1: 1 to 1: 4 and the from glycol monoalkyl ether to water should be about 1.5 to 25: 1. As the alkali metal cyanide, it is particularly advantageous to use the technical sodium cyanide, which still contains about 5% water, the so-called centrifugal salt. If you let z. B. in the slurry of sodium cyanide in water-containing glycol monoalkyl ether at 80 to 100 ° gradually over the course ^of 3 to 5 hours, the calculated amount or an excess of 1,4-dichlorobutane run, so you get in very good yield adipic acid dinitrile in addition to a little <5- Chlorvaleric acid nitrile without undesirable side reactions such as ring closure to 2-cyanocyclopentanoneimine or decomposition or hydrolysis of sodium cyanide taking place to a significant extent. . · ■. ·.

To dissipate the heat of reaction, it is advisable to carry out the reaction under such reduced pressure to carry out that. the mixture at the respective Working temperature boils, some of the water evaporates and the heat of reaction dissipates. Man can also use inert auxiliary liquids such as benzene.

The process has the advantage that one can manage with considerably smaller amounts of glycol monoalkyl ether than ¹ in one of the known processes using this diluent, and that it does not require the use of dry alkali metal or alkaline earth metal cyanide. It is surprising that the presence of water does not interfere and that the reaction takes place sufficiently quickly even at temperatures between about 80 and 10 °. Compared to the earlier proposal already mentioned, the direct yield of adipic dinitrile is better. It differs from the operation of this older proposal not only in the reversal of the procedural measures, but also in the reduction in the amount of waslsler. Here the amount of water to be used is deliberately chosen so that on the one hand one. Raising the temperature of the reaction mixture over 11 o ° is avoided, and that on the other hand the entire inorganic -.-.- cyanide can react via the solution phase with the 1,4-dichloro, butane without the resulting alkali or alkaline earth chloride including undissolved cyanide and so evade implementation. The parts mentioned in the following example are parts by weight.

example

In a heated to 85 ° slurry of λ 980 parts iooo / pc alcohol sodium cyanide (in Foirm ~ a technical, about 5 0/0 water-containing product) in a mixture of 2500 parts of glycol monomethyl ether and 250 parts of water is allowed with stirring in the course of 4 to 5 hours i27oTeile 1,4-dichlorobutane run in, keeping the temperature at 85 to 90 ^0th Only traces of hydrogen cyanide escape. After cooling, the precipitated sodium chloride sucks, the amount of which is about 90 o / _o expected amount, and washed it out with little glycol monomethyl ether. It is completely colorless and, after drying, contains about 5.3% sodium cyanide, which is obtained in the usual way, e.g. B. by adding the calculated amount of hydrochloric acid and collecting the escaping hydrogen cyanide in sodium hydroxide, regenerated who can. Ays the filtrate, the water and most of the glycol monomethyl ether is distilled off, the remaining sodium chloride. fails, '. which still contains about 2 0/0 sodium cyanide.

After this salt mixture has been separated off, it is distilled under reduced pressure. In addition to the remaining glycol monomethyl ether, 25 parts of 1,4-dichlorobutane are initially obtained back; then go below 1 mm pressure 70 parts of (5-Chlorvaleriansäurenitril, bp. 58 to 64 ⁰ to 18 parts of an oxygen-containing. intermediate fraction, bp. 88 ° above. The major amount, 908 parts, made of pure adiponitrile, bp. 150 ⁰ / ι ο Torr.

Since one, is also the o-Ghlorvaleriansäurenitril can be reacted with sodium cyanide again both the recovered 1, 4-D1-chlorobutane as the yield of adiponitrile 87 0/0 (be- -, calculates the 'applied amount of sodium cyanide) and 92 0/0 (calculated on converted 1,4-dichlorobutane).

I PATENT CLAIM:

Process for the preparation of adipic acid dinitrile by introducing 1,4-dichlorobutane in suspensions of alkali or earth, alkali cyanides in glycol monoalkyl ethers at elevated temperature, characterized in that 1,4-dichlorobutane at about 80 to no ⁰ in a suspension of alkali - Or alkaline earth cyanide in 'a mixture of glycol monoalkyl ether and water, the ratio of 1,4-dichlorobutane to glycol monoalkyl ether about 1: 1 to 1: 4 and that of glycol monoalkyl ether to water about 1.5: ι to 25: Should be 1.