Catalytic hydrogenation for the preparation of amines from amide acetals, ketene N, O-acetals or ester imides

Abstract

The present invention relates to a process for the preparation of amines, comprising the following steps: Reaction of a (i) amide acetal of the general formula (I), or (ii) ketene N,O-acetal of the general formula (II), or (iii) ester imide of the general formula (III) with H.sub.2 in the presence of a hydrogenation catalyst, where catalyst and amide acetal or ketene N,O-acetal or ester imide are used in a molar ratio of from 1:10 to 1:100 000 and where a hydrogen pressure of from 0.1 bar to 200 bar is established and where a temperature in the range of from 0 C. to 250 C. is established.

Claims

1. A process for the preparation of amines, comprising reacting one or more compounds with H.sub.2 in the presence of a hydrogenation catalyst, wherein said compounds are selected from the group consisting of: a) an amide acetal of the general formula (I): ##STR00028## wherein: R is selected from the group consisting of H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl or (C.sub.3-C.sub.13)-heteroaryl, CN, COO(C.sub.1-C.sub.18)-alkyl, CONH(C.sub.1-C.sub.18)-alkyl, CF.sub.3; R and R independently of one another are selected from the group consisting of: (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, and (C.sub.2-C.sub.13)-heterocycloalkyl; and R.sup.1 and R.sup.2 independently of one another are selected from the group consisting of: H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.8)-cycloalkyl, (C.sub.2-C.sub.7)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl and (C.sub.3-C.sub.13)-heteroaryl; and wherein, in each case, two radicals selected from R, R.sup.1, R.sup.2, R and R together can form a (C.sub.2-C.sub.8)-alkylene bridge, thus giving a ring with a total of 4-11 ring atoms; b) a ketene N,O-acetal of the general formula (II): ##STR00029## wherein: R is selected from the group consisting of: (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl; R.sup.1, R.sup.2, independently of one another, are selected from the group consisting of: H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl and (C.sub.3-C.sub.13)-heteroaryl; R.sup.3 and R.sup.4, independently of one another, are selected from the group consisting of: H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl, (C.sub.3-C.sub.13)-heteroaryl, CN, COO(C.sub.1-C.sub.18)-alkyl, CONH(C.sub.1-C.sub.18)-alkyl and CF.sub.3; and wherein, in each case, two radicals selected from R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R together can form a (C.sub.2-C.sub.8)-alkylene bridge, thus giving a ring with a total of 3-11 ring atoms; and c) an ester imide of the general formula (III): ##STR00030## wherein: R is selected from the group consisting of: (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl; R is selected from the group consisting of: H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl, (C.sub.3-C.sub.13)-heteroaryl, CN, COO(C.sub.1-C.sub.18)-alkyl, CONH(C.sub.1-C.sub.18)-alkyl, and CF.sub.3; R.sup.1 is selected from the group consisting of: H, (C.sub.1-C.sub.24)-alkyl, (C.sub.3-C.sub.20)-cycloalkyl, (C.sub.2-C.sub.13)-heterocycloalkyl, (C.sub.6-C.sub.14)-aryl and (C.sub.3-C.sub.13)-heteroaryl; and wherein, in each case, two radicals selected from R, R.sup.1 and R together can form a (C.sub.2-C.sub.8)-alkylene bridge, thus giving a ring with a total of 4-11 ring atoms; and wherein said catalyst and said amide acetal, ketene N,O-acetal, or ester imide are used in a molar ratio of from 1:10 to 1:100 000 and the reaction is carried out at a hydrogen pressure of from 0.1 bar to 200 bar and a temperature of from 0 C. to 250 C.

2. The process of claim 1, wherein the hydrogenation catalyst comprises at least one active metal.

3. The process of claim 2, wherein the active metal is a metal of group VII B and/or VIII B of the Periodic Table of the Elements.

4. The process of claim 1, wherein the reaction is carried out in a solvent.

5. The process of claim 4, wherein the solvent is selected from the group consisting of hydrocarbons, chlorinated hydrocarbons, ethers, esters and alcohols.

6. The process of claim 5, wherein an anhydrous solvent is used.

7. The process of claim 1, wherein the reaction is carried out without solvents.

8. The process of claim 2, wherein the reaction is carried out in a solvent.

9. The process of claim 8, wherein the solvent is selected from the group consisting of hydrocarbons, chlorinated hydrocarbons, ethers, esters and alcohols.

10. The process of claim 9, wherein an anhydrous solvent is used.

11. The process of claim 2, wherein the reaction is carried out without solvents.

12. The process of claim 11, wherein the active metal is a metal of group VII B and/or VIII B of the Periodic Table of the Elements.

13. The process of claim 1, wherein the compounds comprise an amide acetal of formula (I) as described in paragraph a).

14. The process of claim 13, wherein the reaction is carried out in a solvent selected from the group consisting of hydrocarbons, chlorinated hydrocarbons, ethers, esters and alcohols.

15. The process of claim 13, wherein the reaction is carried out without solvents.

16. The process of claim 1, wherein the compounds comprise a ketene N,O-acetal of formula (II) as described in paragraph b).

17. The process of claim 16, wherein the reaction is carried out in a solvent selected from the group consisting of hydrocarbons, chlorinated hydrocarbons, ethers, esters and alcohols.

18. The process of claim 16, wherein the reaction is carried out without solvents.

19. The process of claim 1, wherein the compounds comprise an ester imide of formula (III) as described in paragraph c).

20. The process of claim 19, wherein the reaction is carried out without solvents.

Description

WORKING EXAMPLES

(1) The examples below serve to illustrate the invention without limiting it thereto.

Example 1

Reworking of Experiment 1 from the Patent Specification DE-604277 (1934)

(2) In a 300 ml autoclave, benzyliminoethyl ether hydrochloride (37 g, 0.2 mol) is suspended in 30 ml of cooled absolute ethanol and, after adding 0.5 g of platinum oxide (Adams) catalyst, is flushed with hydrogen, then 40 bar hydrogen were injected in and the mixture was stirred at 30 C. and a constant pressure for 12 hours. After filtering from the catalyst and distilling off the solvent, the residue was admixed with 50 ml of 2N sodium hydroxide solution, and the product is extracted with diethyl ether. The organic phase is dried over K.sub.2CO.sub.3, the solvent is removed on a rotary evaporator, and the residue is analyzed by means of GC-MS and NMR spectroscopy. The mixture consists of 2% benzylamine, 21% (cyclohexylmethyl)amine and 77% di(cyclohexylmethyl)amine.

Examples 2-19

(3) In a 10 ml autoclave, an amide acetal (5 mmol) is dissolved in 5 ml of absolute methanol, and, after adding 1 mol % catalyst, flushing with hydrogen is carried out. 40 bar of hydrogen are then injected in, and the mixture is stirred at 25 C. and a constant pressure until hydrogen absorption is no longer evident (1-2 h). After filtering off from the catalyst, the reaction solution is admixed with 10 ml of 1 M HCl solution in methanol, the solvent is removed on a rotary evaporator, and the residue is admixed with ether. The solid amine hydrochloride is filtered off, washed with diethyl ether and dried in vacuo.

Example 20-25

(4) In an autoclave, 2-ethoxy-2-methyl-3-benzyloxazolidine (5.55 g, 25 mmol) is dissolved in 25 ml of absolute ethanol and, after adding 1 mol % catalyst, flushing with hydrogen is carried out. 40 bar of hydrogen are then injected in, and the mixture is stirred at 25 C. and a constant pressure until hydrogen absorption is no longer evident (2-3 h).

(5) Separation off from the catalyst and distillation gives N-benzyl-2-(ethylamino)ethanol: b.p. 63 C./0.03 mbar; Rf=0.33 in ethyl acetate; .sup.1H NMR (CDCl.sub.3) 7.33-7.37 (m, 4H), 7.27-7.30 (m, 1H), 3.66 (s, 2H), 3.60 (t, J=5.4, 2H), 2.96 (br. s, OH), 2.69 (t, J=5.4, 2H), 2.61 (q, J=7.2, 2H), 1.10 (t, J=7.2, 3H).

(6) The catalysts used and yields of Examples 2-25 can be found in Table 2.

(7) TABLE-US-00002 TABLE 2 Yields of Examples 2-25. Examples 2-7 8-13 14-19 20-25 Amide acetal 0 Amine NMe.sub.3 EtNMe.sub.2 5% Pd/C 60% 84% 74% 80% 5% Pd/Al.sub.2O.sub.3 70% 99% 64% 50% 5% Pd/CaCO.sub.3 74% 93% 69% 40% 5% Pt/C 78% 82% 99% 82% 5% Ru/Al.sub.2O.sub.3 83% 80% 76% 22% [(dppb)Rh(cod)]BF.sub.4 96% 97% 95% 97%

Examples 26-31

(8) In an autoclave, an ester imide (25 mmol) is dissolved in 25 ml of absolute methanol or ethanol and, after adding 5% Pt/C (975 mg, 1 mol %), flushing with hydrogen is carried out. 40 bar of hydrogen are then injected in, and the mixture is stirred at 25 C. and constant pressure for 16 hours. After separation off from the catalyst, the filtrate is distilled.

(9) The reaction conditions and yields can be found in Table 3.

(10) TABLE-US-00003 TABLE 3 Reaction conditions and yields of Examples 26-31. Exam- Yield, ple Ester imide Product Solvent % 26 EtOH 86 27 MeOH 84 28 0 MeOH 85 29 60 19 30 (C.sub.5H.sub.11).sub.2NH EtOH 88 31 Bn.sub.2NH EtOH 85

Example 32

(11) ##STR00027##

(12) In an autoclave, 2-dimethylamino-2-ethoxy-1-cyanoethylene (7 g, 50 mmol) is dissolved in 20 ml of absolute ethanol. After adding 5% Pt/C (975 mg, 0.5 mol %), the autoclave is flushed with hydrogen, then 40 bar of hydrogen are injected in, and the mixture is stirred at 50 C. and a constant pressure for 16 hours. After filtering off from the catalyst and distilling off the solvent, the residue is taken up in diethyl ether, washed with concentrated NaCl solution and dried over MgSO.sub.4. Distillation gives 3.1 g (65%) of 3-(dimethylamino)acrylonitrile; Kp=66 C./0.1 mbar, .sup.1H NMR (CD.sub.2Cl.sub.2) (preferred isomer) 6.95 (d, J=13.6, 1H), 3.70 (d, J=13.5, 1H), 2.86 (br. S, 6H).