DE2319360A1 - PROCESS FOR THE PRODUCTION OF EPSILONAMINOCAPRONIC ACID AMIDE - Google Patents

Description

Badische Anilin- & ooda-Faorik AG

Our reference: O.Z. 29 8 ^ 1 Moe / UB

6700 Ludwigshafen, April 13, 1973

Process for the preparation of 8-aminocaproic acid amide

The invention relates to a process for the preparation of ε-aminocaproamide from E-ITitrocaproamide.

Those -Japanese Patent Application 40 610/71 "describes the catalytic reduction of G-Nitrocapronamid to £ -Aminocapronamid" at temperatures below 150 ⁰ G in inert solvents (1 "to 20 times G-ewiehtsmenge). As such, methanol, ethanol , Tetrahydrofuran, dioxane and water.

Japanese patent application 15 486/70 describes the preparation of 6-aminocapronamide directly from 2-nitrocyclohexanone, the isolation of the ε-nitrocapronamide not being necessary. Again, the catalytic reduction is carried out under pressure in a solvent (1-bia 20 times G-ewichtsmenge) in the presence of ammonia at temperatures below 150 ⁰ C in very good yields.

Disadvantageous in the production of f-aminocaproamide from 2-nitrocyclohexanone is the need to allow the reaction to take place in a relatively narrow temperature range (5 - 75 C), to obtain high yields of aminoamide. Otherwise, mixtures of aminocaproamide and aminocaproic acid are obtained.

The reduction of 6-nitrocaproamide to 6-aminocaproamide in inert Solvent is, due to the high energy costs, necessary for the separation and purification of the solvent are defective.

It has now been found that receives £ -Aminocapronamid in high yields and in good purity if £ -Nitrocapronsäureamid egenwart G with hydrogen in liquid ammonia under pressure at temperatures of 50 to 150 ⁰ C in a conventional active reduction catalyst is reduced.

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The implementation can be formulated as follows:

i? 3 H °

NO ₂ -OH ₂ - (OH _{2) 4} -Ö-NH ₂ ^2> NH ₂ -OH ₂ - (OH _{2) 4} ~ 0 ΝΗ ₂ + 2 H ₂ O

The formation of by-products cannot be observed. It takes place no decrease in the catalytic activity during the reaction in the process according to the invention. This beneficial The result is surprising because in the German Offenle- "" ■ 'gungsschrift 1 932 218 describes that the catalytic activity of a hydrogenation contact in the pH range above 13 decreases and thereby also the rate of reaction of the hydrogenation.

A particular advantage of the invention is the extremely easy separation of the aminocaproic acid amide formed from the reducing contact. It has been found that aminocaproamide is completely soluble in liquid ammonia. Therefore, after the reaction has ended, the reduction contact can be made, for example, by filtration completely separated from the aminocaproamide dissolved in the liquid ammonia After the ammonia has evaporated, the aminocaproamide will be obtained in such purity that it is without additional Cleaning can be processed further.

The liquid ammonia is used for the method according to the invention as a solvent. The amount used is not critical, but should be so high that one at the reduction temperature homogeneous mixture of C-nitrocaproic acid amide, hereinafter briefly Called e-nitrocapronamide, it is present in liquid ammonia. the The necessary amount of ammonia is represented by the solution equilibrium f-nitrocapronamide-ammonia (figure). So lies the chosen amount of ammonia in the range of 10-50 moles per mole used f-nitrocapronamide, but a higher ammonia concentration not disadvantageous for the process according to the invention.

Generally the reaction is carried out at a temperature between 50 and 15O ° C, preferably at 70 to 130 ⁰ O, in particular at

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Temperatures between 90 and 120 ^° C. and a pressure of 20 to 200 bar, preferably 50 to 150 bar, in particular at a pressure: between 80 and 120 bar, continuously or discontinuously.

As an active hydrogenation catalyst for use in the context of In the invention, all known catalysts can be used in the catalytic hydrogenation according to the invention are effective under the listed reaction conditions. Useful catalysts include cobalt, winding, Palladium, platinum and compounds which form these metals under the conditions according to the invention. For example be nickel-containing catalysts such as reduced nickel, Raney nickel or the like, palladium-containing catalysts, such as Palladium-carbon, palladium-barium sulfate or the like, platinum-containing catalysts such as platinum-carbon, platinum oxide or the like as well as cobalt-containing catalysts such as -Raney cobalt, reduced cobalt or the like, possibly on supports, advantageously used.

The amount of catalyst used is not critical. The preferred one Range is 0.1 - 40 G-ew. $, especially 0.5-10 Weight $, based on the starting material used.

The reaction can be carried out as follows: In a pressure-tight The reaction vessel becomes i-ltitrocapronamide, hydrogenation contact and ammonia entered. Then, hydrogen is introduced under pressure and the reaction system is brought to the reaction temperature with stirring brought and implemented. The reaction is continued until the hydrogen uptake has practically ended. After the reaction, the reaction mixture is allowed to cool and the pressure is released the reaction vessel takes up the reaction residue in an inert solvent and separates off the hydrogenation contact. However, you can also remove the hydrogenation contact under pressure and then the reaction mixture in a zone of low Pressure, releasing ammonia.

The f-aminocaproamide obtained in this way is free from impurities

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and can therefore continue to be implemented without cleaning measures .

The i-aminocaproamide which can be prepared according to the process of the invention is a valuable intermediate for the manufacture of caprolactam. It is well known that caprolactam is an important starting material for nylon 6, which is widely used in the form of synthetic fibers and resins.

The invention is explained in more detail below with the aid of examples, which serve only for illustration and do not limit the invention.

example 1

In a 250 ml steel autoclave are 7.2 g (0.045 mol) £ - Nitrocapronamid, 2.9 g of Raney nickel and 50 ml of liquid ammonia added, hydrogen pressed bar up to a pressure of 100 and heated with stirring to 100 ⁰ O. After 2 hours at the reaction temperature, the autoclave is cooled and let down. The residue is taken up in benzene, the Hydrierungskontakt filtered off and the f-aminocaproamide, after evaporation of the solvent in the form of white crystals of melting point 50 - 51 ⁰ C obtained. The infrared absorption spectrum of this substance completely agrees with that of C-aminocaproamide. Yield 90.5 # (lit. m.p. 51-52 °).

Example 2

In a reduction vessel 8.0 g (0.05 mol) £ -Nitrocapronamid in 50 ml of liquid ammonia in the presence of 2.0 gVPalladium on activated carbon (10 $ Pd) at 100 ⁰ C and a hydrogen pressure of 100 bar reacted with stirring. The reduction is complete after 2 hours, the reducing contact is filtered off and the ammonia is distilled off under reduced pressure. 6.5 g (yield $ 100) of f-aminocaproamide, which is pure according to thin-layer chromatography, are obtained.

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Example 3

In a 250 ml autoclave, 8.0 g (0.05 mol) £ - Nitrocapronamid heated 25 ml of liquid ammonia and 2.0 g of nickel .Kieselgur (37 $ Ni) at 100 "bar hydrogen pressure with stirring to 100 ⁰ C. After. 2 hours the autoclave is cooled and depressurized. The reaction mixture is treated in the same way as in Example 1 "and f-aminocaproamide is obtained with a yield of $ 88;

Example 4

8.0 g (0.05 mol) of ε-nitrocaproamide, 50 ml of liquid ammonia and 2.0 g of nickel on kieselguhr (Ni content $ 49) and hydrogen up to an initial pressure of 100 bar are introduced into an autoclave of 250 ml initiated. The system is stirred at 100 ⁰ C. After 1 hour, no further hydrogen absorption can be detected. The reaction is ended after further stirring for 30 minutes. The reaction mixture is cooled, let down and taken up in ethanol. After filtering off the hydrogenation contact, 6.4 g of f-aminocaproamide are obtained after concentration. The reaction product is pure according to thin layer chromatography. The yield is 98 %.

Example 5

8.0 g of ε-nitrocapronamide, 2.0 g of palladium on barium sulfate (5 # Pd) and 50 ml of liquid ammonia are introduced into a catalytic hydrogenation reaction vessel with a capacity of 250 ml and the mixture is stirred at 100 ^° C. and a hydrogen pressure of 100 bar for 2 hours. The reaction mixture is treated in the same manner as in Example 1 to obtain 6.4 g (98 i »yield) £ -Aminocapronamid.

Example 6

In a 250 ml autoclave, 8.0 g (0.05 mol) of 6-nitroeapronamide, dissolved in 50 ml of liquid ammonia, in the presence of 2.0 g of platinum on activated carbon (5 $ Pt) under a pressure of 50 bar hydrogen for 2 hours hydrogenated at 50 ⁰ C. The reaction

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mixture is treated in the same else ¥ as in Example 4 and 6-Amlnocapronamid 5.2 g of melting point .52 - 53 ⁰ C obtained. The yield is 85 ^.

Example 7

In a 250 ml autoclave, 8.0 g (0.05 mol) of f-Nitrocapronamid, 20 ml of liquid ammonia and 2.0 g Raney cobalt are incorporated and stirred bar 5 hours at 120 ⁰ C and a hydrogen pressure of 80 s. The reaction mixture is treated in the same way as in Example 1. It comes in a yield of 78 $> pure £ -Aminocapronamid of melting point 50 - received 51 ⁰ C.

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Claims (5)

- 7 - O.Z. 29 8 ^ 1 Claims Process for the preparation of 6-aminocaproamide by reducing t-nitrocaproamide, characterized in that • that C-nitrocaproamide is reduced with hydrogen in liquid ammonia under pressure at temperatures of 50 to 150 ° C. in the presence of a customary active reduction catalyst. 2. The method according to claim 1, characterized in that such an amount of liquid ammonia is used as solvent, which is sufficient to completely dissolve the C-nitrocapronamide used at the reaction temperature. 3. The method according to claim 1 and 2, characterized in that at least one metal from group VIII of the periodic table or the compounds which form the metals in the reaction system is used as the active hydrogenation catalyst. 4. The method according to claim 1 to 3, characterized in that the active hydrogenation catalyst used is nickel, cobalt, platinum or palladium or the compounds which these metals form in the reaction system. 5. The method according to claim 1 to 4, characterized in that the active hydrogenation catalyst is separated off after the reaction under the pressure prevailing in the reaction system. Badische Anilin- & Soda-Fabrik AG Ten. 409845/1032 Read more