DE2042760B2 - Process for the production of long chain diamines - Google Patents

Description

The invention relates to a process for the preparation of aliphatic, unbranched Ce-C | g-diamines from the corresponding aliphatic, unbranched Ct-Ci8-dinitriles with the aid of hydrogen in the presence of NH3 and hydrogenation catalysts by known methods. The process is characterized in that primary or secondary monoamines or compounds which give these monoamines under the hydrogenation conditions are added to the dinitriles before the reaction.

It is known to produce aliphatic, unbranched or branched diamines by hydrogenating the corresponding To produce dinitriles with the aid of hydrogen in the presence of NH3 and hydrogenation catalysts. If one now applies these known methods to the hydrogenation of aliphatic, unbranched Cb-Ci8-dinitriles, it is observed that the In the case of a fixed bed arrangement, the hydrogenation catalyst disintegrates mechanically after a comparatively short standing time. The disintegration of the contact grain occurs regardless of how the reactants are conducted through the catalyst bed on, d. H. both in the trickle process and in the continuous sump phase hydrogenation, in which the dinitrile or a solution of the dinitrile flows through the reactor from bottom to top, likewise with a procedure in which the dinitrile or its solution in countercurrent to the Hydrogen is passed. Due to the catalyst disintegration occur when flowing through the reactor Stream formations that lead to a significant deterioration in the process, which is inadmissible for the process Lead hydrogenation, and result in a reduced yield and a deterioration in the quality of the Precipitate pure diamine prepared by distillation.

In the further course, certain contact areas completely destroyed, so that further operation of the reactor is impossible.

There are various methods in the patent literature for suppressing the phenomenon described has been described. So you can by adding solvents, such as N H3, or by recycling a Part of the material to be hydrogenated, in particular the crude, amnioniacal diamine solution, as found on the Reaktoraiistriit occurs, avoid local overheating of the catalytic converter. Catalyst types have also been developed been, in which by suitable additives such. B. pyro or polyacids forming components, a higher a lower hydrogenation temperature is achieved or by adding metallic activators (manganese, chromium) is made possible, which in turn causes an extended service life.

However, the known measures for extending the service life of the catalyst do not lead in all cases to satisfactory results. Depending on the structure and carbon number of the dinitrile to be hydrogenated, otherwise different degrees of pulverization observed after a defined period of operation under the same conditions.

It has now been found that the disadvantages of the known processes can be avoided by the process for the production of aliphatic, unbranched Cg-Cis-diamines from aliphatic, unbranched Ce-Cig dinitriles with the aid of hydrogen in the presence of NH3 and hydrogenation catalysts by known methods so that the Dinitriles added primary or secondary monoamines or compounds under the Hydrogenation conditions give these monoamines.

This process can be used particularly well in the hydrogenation of the dinitriles, which are as have proven to be particularly effective in disintegration, such as adipic acid dinitrile, suberic acid dinitrile, azelaic acid dinitrile, sebacic acid dinitrile, Decanedicarboxylic acid dinitrile, hexadecanedicarboxylic acid dinitrile, or the corresponding unsaturated ones Dinitrile, ζ. Β. 2-butene-1,4-dicarboxylic acid dinitrile.

An advantageous embodiment of this process is that the monoamine is a cycloaliphatic Amine used. Additional effects are also obtained if a secondary amine is used as the monoamine begins.

Suitable monoamines for the purposes of the invention are i) aliphatic, primary amines, such as methylamine, Ä hylamine, Isopropylamine, hexylamine, stearylamine, and also aromatic amines such as aniline and benzylamine.

Examples of suitable cycloaliphatic amines are

Cyclohexylamine,
of 3,3,5-trimethylcyclohexylamine,

2,4,4-trimethylcyclopentylamine and
3-aminomethyl-3,5,5-trimethylcyclohexanol.
Secondary amines are particularly suitable, such as

Diisopropylamine,
Vi pyrrolidine,

2,4,4-trimethylpyrrolidine,
Piperidine,

3,3-dimethylpiperidine,
Hexamethyleneimine,

M 3,3,5-trimethyl-1-azaeycloheptane,
3,5,5-trimethyl-l-azacycloheptane,
or their mixtures,
l ^ -trimethyl-b-azatricyclo-p ^ JJ-octane,
Dicyclohexylamine,
Bis (3,3,5-trimethylcyclohexylamine).

Compounds which give monoamines under the hydrogenation conditions are for example
1,6-diamino-2,2,4-trimethylhexane,
1,6-diamino-2,4,4-trimethylhexane,
w) S-aminomethyl-S ^ S-trimethylcyclohexylamine,
Acetone,

Methyl isobutyl ketone,
Cyclohexanone,
3,3,5-Trimelhy! Cyclohexanone,
b ") furfural and

Isobutyraldehyde.

The hydrogenation conditions and catalysts are otherwise the same! those of known processes water

Substance is used in hydrogenation quality.

The hydrogenation is generally conducted at temperatures ranging from 60 to 250 ° C, preferably 80 to 200 ⁰ C, carried out

The pressures occurring during the hydrogenation are in the range from 100 to 1000 atm. preferably 150 to 450 atü. These pressures are to be understood as meaning the total pressure of the reaction.

The known compounds containing nickel or cobalt are preferably used as hydrogenation catalysts

The products according to the invention are industrially interesting intermediates for Manufacture of plastics and synthetic resins.

The method according to the present invention is illustrated by the following examples:

example 1
(Comparative example)

100 liters of cobalt contact (24% Co, 6% MnO on pumice stone, ^{reduced at 350 °} C.) were filled into a reactor with an internal width of 300 mm and a length of 1800 mm. 15 kg of 1,10-decanedicarboxylic acid dinitride and 100 liters of liquid ammonia were pumped in over the catalyst at 300 atm. Hydrogen pressure in such a way that nitrile and ammonia were completely mixed with one another before entry into the contact zone and also trickled through the catalyst chamber in a uniform distribution. The nitrile / NH3 mixture was preheated to 85 ° C; the maximum hydrogenation temperature was 125 ° C. From the lower part of the product flowed Hydrierofens after cooling to 60 ⁰ C in a pressure separator in which hydrogen and ammoniacal diamine were separated. The gas space of the separator was connected to the lower part of the reactor.

The resulting liquid product was let down to 35 atmospheres, the ammonia by distillation under this pressure separated and reinserted.

The raw diamine and its composition were further processed by means of vacuum distillation the analysis shows as follows:

Operating time (hours) 240 360 480 I. 48 0.4 0.4 0.4 I C || - diamine (%) 0.4 98.7 98.5 95.1 I C | i-diamine (%) 98.7 0.02 0.05 0.84 I C | 2-aminonitrile (%) 0.01 0.01 0.08 2.14 ρ CirDinitrile (%) 0.01 0.8 0.9 1.4 I higher boilers 0.9 I polyamines (%) ί

The catalyst was removed after approx. 500 operating hours. The degree of pulverization was in upper half of the reactor 65%, in the lower part 7%.

Example 2

In the hydrogenation plant described in Example 1 were over a freshly introduced catalyst of the same type at a hydrogen pressure of 300 atmospheres per hour 15 kg of decanedicarboxylic acid dinitrile, 301 of a mixture from 3,3,5- and 3,5,5-trimethyl-1-azacycloheptane and 701 liquid ammonia passed from the reaction mixture were ammonia under a pressure of 35 atü, the used sec. The monoamine was separated off by distillation in vacuo at 80 torr

The analysis of the crude product showed the following changes as the operating age of the catalyst increased:

Operating time (hours)
48 360 980

2245

0.4 0.4 0.4 0.4 98.5 98.4 98.3 98.1 0.03 0.03 0.04 0.08 0.01 0.01 0.01 0.01 1.0 1.1 1.1 1.3

C |] diamine (%)
Cn diamine (%)
C | ₂ -Aminonitri! ι
C | 2-dinitrile (%)
Higher boiling

jo polyamines (%)

After approx. 2300 operating hours the pulverization was 5 Degree of efficiency of the removed catalyst in the upper half 8%, in the lower part of the reactor less than 5%.

Example 3

In an electrically heated shaft furnace there were 500 cm ³ of a cobalt-nickel catalyst (made by sintering 10 parts of cobalt oxide and 1 part of nickel formate in iioo ⁰ C, then molding, and reducing at 380 ⁰ C). 100 cm ^{3 of} a mixture of 50 g of adipic dinitrile and 50 g of cyclohexylamine and 500 ml of liquid NH3 were pumped into the upper part of the reactor every hour. The hydrogenation was carried out at a maximum of 125 ° C. under a total pressure of 300 atmospheres. 200 l of hydrogen gas were withdrawn from the downstream separator.

The aminocapronitrile content in the emerging crude diamine was 180 even after a hydrogenation period Days still below 0.01%. The yield of pure hexamethylenediamine was after work-up by distillation 94% d. Th.

Claims (2)

Patent claims: 1. A process for the preparation of aliphatic, unbranched C * -Ci8-diamines from the corresponding aliphatic, unbranched Q> - Ci8-dinitriles with the aid of hydrogen in the presence of NH3 and hydrogenation catalysts according to known methods, characterized in that the dinitriles before the Reaction adds primary or secondary monoamines or compounds which give these monoamines under the hydrogenation conditions. 2. The method according to claim 1, characterized in that the primary or secondary monoamine is a cycloaliphatic.