WO2001021581A1

WO2001021581A1 - Process for the partial hydrogenation of a nitrile compound containing two or more nitrile groups

Info

Publication number: WO2001021581A1
Application number: PCT/NL2000/000673
Authority: WO
Inventors: Robert Pestman
Original assignee: Dsm N.V.
Priority date: 1999-09-22
Filing date: 2000-09-21
Publication date: 2001-03-29
Also published as: NL1013112C2; AU7969600A

Abstract

Process for the preparation of a mixture of an aminonitrile and an amino compound containing two or more amino groups through partial hydrogenation of a nitrile compound containing two or more nitrile groups using hydrogen in the presence of a Raney catalyst, hydroxide base and water, the hydroxide base/catalyst weight ratio being more than 0.05 and the water/catalyst weight ratio being less than 2.

Description

PROCESS FOR THE PARTIAL HYDROGENATION OF A NITRILE COMPOUND CONTAINING TWO OR MORE NITRILE GROUPS

The invention relates to a process for the preparation of a mixture of an aminonitrile and an amino compound containing two or more amino groups through partial hydrogenation of a nitrile compound containing two or more nitrile groups using hydrogen in the presence of a Raney catalyst, a hydroxide base and water, and also relates to a mixture of an aminonitrile, an amino compound and a nitrile compound.

Such a process is known from WO-A-96/18,603. This publication describes a process for the partial hydrogenation of aliphatic dinitriles into the corresponding aminonitrile using hydrogen in the presence of a Raney nickel or a Raney cobalt catalyst, a strong mineral alkaline or alkaline earth base and water.

Drawbacks of the process according to WO-A-96/18,603 are: - a long reaction time;

- if the mixture is to have a low amino compound content, the reaction must be stopped at a very low degree of conversion of the nitrile compound; and

- the reaction cannot be controlled with respect to the ratios of aminonitrile and amino compound to be produced. The aim of the invention is to provide a process that does not present the aforementioned drawbacks.

The invention is characterized in that the hydroxide base/catalyst weight ratio is more than 0.05 and the water/catalyst weight ratio is less than 2. This results in a high reaction rate and a high degree of conversion, while moreover the aminonitrile and amino compound yields can be controlled.

The process according to the invention is suitable for the partial hydrogenation of a nitrile compound containing two or more nitrile groups. The process according to the present invention is preferably suitable for the partial hydrogenation of compounds containing two to ten nitrile groups. The hydrogenation of nitrile compounds is represented by the following reaction scheme:

(A) (B) (C)

R - (C ≡ N)_x— > (H - N - CH₂)_Z - R - (C ≡ N)_y + (H - N -CH₂)_X - R

H H

where 2 < x < 10, 1 < y < 9, 1 < z < 9 and y + z = x;

R may be a saturated or unsaturated, linear or branched hydrocarbon radical with

1-20 carbon atoms. Examples of such hydrocarbon radicals are methylene, ethylene, propylene, 1-methylpropylene, butylene, pentylene, hexylene and decylene. In addition to, or instead of carbon, R may also contain one or more heteroatoms from groups 14-17 of the Periodic System of the Elements. R may for example be an N-containing group or a halogen. Compound (A) is a nitrile compound containing at least 2 and at most 10 nitrile groups. Hydrogenation causes compound (A) to react to form a mixture of compound (B), an aminonitrile and compound (C), an amino compound. If the nitrile compound contains more than two nitrile groups, i.e. x > 2, then compound B represents a mixture of all the possible aminonitriles that may be formed as a result of the partial hydrogenation of that specific nitrile compound. Preferably, α,ω-alkane dinitriles are suitable for being converted into a mixture of their corresponding aminonitriles and amino compounds using the process according to the present invention. These alkane dinitriles have a general formula NC-(C_nH_2n )-CN, where n is a whole number between 1 and 12. Preferably, n is a whole number between 1 and 6. The following can be mentioned as examples: malonitrile (n=1 ), succinonitrile (n=2), adiponitrile (n=4), 2- methylglutaronitrile (n=4) and glutaronitrile (n=3). The process according to the invention is particularly suitable for the hydrogenation of succinonitrile and adiponitrile.

The catalyst used according to the invention is a Raney catalyst. Examples are Raney nickel or Raney cobalt. Mixtures of Raney nickel and Raney cobalt may also be used. Raney catalysts and their preparation are for example described in US-A-1 ,628,190.

The Raney catalyst may contain small amounts of other metals in an elementary or chemically bound form from groups 4, 6 - 10 of the Periodic System of the Elements. The 'Periodic System of the Elements' is here understood to be the Periodic System represented on the inside of the cover of the Handbook of Chemistry and Physics, 70th Edition, 1989/1999 (New IUPAC Notation). The amount of other metals may vary from 0 wt.% to 15 wt.% relative to the weight of nickel or cobalt, and preferably from 0 to 10 wt.%. This addition of other metals can increase the activity and selectivity for the hydrogenation of certain groups of compounds. These other metals are preferably chromium, titanium, molybdenum, iron, zinc and tungsten. Particularly suitable are chromium, titanium and iron or mixtures of these. These other metals are usually referred to as promoters, the catalyst as a promoted Raney catalyst. Promoters are for example described in S.R. Montgomery, Catalysis of Organic Reactions 5, pp. 383-409.

The hydrogenation is effected with hydrogen gas (H₂), in the presence of hydroxide base and water.

The hydroxide base to be used can be chosen from: LiOH, KOH, NaOH, RbOH, CsOH and NH₄OH and their mixtures. In practice, NaOH and KOH are mostly used on account of their good price-quality ratio.

The hydrogenation according to the invention is to be carried out with a hydroxide base/catalyst weight ratio of more than 0.05 and a water/catalyst weight ratio of less than 2. Preferably, the hydroxide base/catalyst weight ratio is more than 0.05 and less than 1.0 and in particular more than 0.05 and less than 0.3. The water/catalyst weight ratio is preferably more than 0.1 and less than 2 and in particular more than 0.4 and less than 1.5.

The nitrile compound can be dissolved in a suitable solvent for the hydrogenation. Examples of suitable solvents are: alcohols such as methanol and ethanol, liquid ammonia and diamines such as ethylene diamines. Preferably, the reaction mixture acts as a solvent during the reaction.

The temperature during the hydrogenation is 40-200°C and preferably 40-120°C. Within this preferred range, the higher the temperature during the hydrogenation, the better the reaction. The pressure during the hydrogenation is 0.5-20 MPa, preferably

4-8 MPa.

A mixture of an aminonitrile, an amino compound and a nitrile compound is also known from WO-A-96/18,603. The mixture obtained according to WO-A-96/18,603 contains at least 60 wt.% aminonitrile.

A disadvantage of mixtures like those obtained in WO-A- 96/18,603 is that the mixture contains even more than 9 wt.% nitrile compound, so that inefficient use is made of the starting material and, in addition, it is difficult to obtain the aminonitrile or the amino compound in a pure form. The aim of the invention is to provide a mixture that does not show the aforementioned disadvantage.

The invention is characterized in that the mixture contains more than 40 wt.% aminonitrile and less than 9 wt.% of the nitrile compound.

This ensures that the starting material is efficiently used and that it is easier to purify the mixture into aminonitrile or amino compound.

The mixture preferably contains more than 50 wt.% aminonitrile and less than 5 wt.% nitrile compound.

The products that can be prepared according to the invention are widely used as raw materials for the production of for example lactams. The invention will be elucidated below with reference to examples without restricting the invention hereto.

Examples

The following abbreviations are frequently used in the examples: SN = succinonitrile

ABN = aminobutyronitrile DAB = diaminobutane

Example I A Raney nickel containing 2.5 wt.% Cr and 2.5 wt.% Fe was used as the catalyst. An autoclave with a volume of 160 ml was used as the reactor. 8 grams of catalyst and the amount of hydroxide base aimed at and the amount of water aimed at in 90 grams of ethylenediamine were introduced into the autoclave. The pressure was then brought to 7 MPa and the temperature was increased to 80°C with stirring (1000 rpm). After the right temperature had been reached, 8 grams of succinonitrile, dissolved in 12 grams of ethylenediamine, was injected. The injection of succinonitrile is taken as time zero (t=0). The reaction was stopped after 6.5 minutes. The product was analyzed. The degree of conversion of the succinonitrile was 99.4 mol%. The reaction product consisted of 76.13 mol% aminobutyronitrile (ABN), 19.29 mol% diaminobutane (DAB) and 4.59 mol% other products. Other products are products like pyrrolidine, pyrroline and other possible coupling products of DAB, ABN and pyrrolidine.

Examples ll-IV

Succinonitrile was hydrogenated as in Example I, the only difference being the hydroxide base used. The results are given in Table 1.

Example V Succinonitrile was hydrogenated as in Example IV, but now different amounts of hydroxide base were used. The results are given in Table 1.

Example VI

Succinonitrile was hydrogenated as in Example IV, but now different amounts of water were used. The results are given in Table 1.

Examples VII- VIII

Succinonitrile was hydrogenated as in Example IV, but now different reaction times were used. The results are given in Table 1.

Table 1

Claims

C L A I M S

1. Process for the preparation of a mixture of an aminonitrile and an amino compound containing two or more amino groups through partial hydrogenation of a nitrile compound containing two or more nitrile groups using hydrogen in the presence of a Raney catalyst, hydroxide base and water, characterized in that the hydroxide base/catalyst weight ratio is more than 0.05 and the water/catalyst weight ratio is less than 2.

2. Process according to Claim 1 , characterized in that the hydroxide base/catalyst weight ratio is more than 0.05 and less than 1.

3. Process according to Claim 1 , characterized in that the hydroxide base/catalyst weight ratio is more than 0.05 and less than 0.3.

4. Process according to any one of Claims 1 -3, characterized in that the water/catalyst weight ratio is more than 0.1 and less than 2. 5. Process according to any one of Claims 1 -3, characterized in that the water/catalyst weight ratio is more than 0.4 and less than 1.

5.

6. Process according to any one of Claims 1 -5, characterized in that KOH and/or NaOH is used as the hydroxide base.

7. Process according to any one of Claims 1 -6, characterized in that the Raney catalyst is a Raney nickel or a Raney cobalt catalyst.

8. Process according to any one of Claims 1 -7, characterized in that the nitrile compound containing two or more nitrile groups is an α,o alkane dinitrile.

9. Process according to Claim 8, characterized in that the α,ω-alkane dinitrile is succinonitrile or adiponitrile.

10. Mixture of an aminonitrile, an amino compound containing two or more amino groups and a nitrile compound containing two or more nitrile groups, characterized in that the mixture contains more than 40 wt.% aminonitrile and less than 9 wt.% of the nitrile compound.

11. Mixture according to Claim 10, characterized in that the mixture contains more than 50 wt.% aminonitrile and less than 5 wt.% nitrile compound.