Method for preparing methionine

Patent metadata

Field	Value
Publication number	US-10899706-B2
Application number	US-201716471338-A
Country	US
Kind code	B2
Filing date	Dec 15, 2017
Priority date	Dec 21, 2016
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

The present invention relates to a method for preparing methionine or methionine salts. In particular, the invention describes the step of preparing 2-hydroxy-4-(methylthio)butyronitrile (MMP-CN) from 3-methylthiopropanal (MMP) and hydrogen cyanide (HCN) in the presence of ammonia by bringing a gaseous mixture comprising HCN and ammonia into contact with MMP.

First claim

The invention claimed is:

1. A method for preparing 2-hydroxy-4-(methylthio)butyronitrile, the method comprising:
bringing a gas mixture comprising hydrogen cyanide and ammonia into contact with 3-methylmercaptopropionaldehyde, thereby producing a product mixture comprising 2-hydroxy-4-(methylthio)butyronitrile.

2. A method for preparing methionine or a salt of methionine, the method comprising:
bringing a gas mixture comprising hydrogen cyanide and ammonia into contact with 3-methylmercaptopropionaldehyde, thereby producing a product mixture comprising 2-hydroxy-4-(methylthio)butyronitrile.

3. The method of claim 1 , in which a molar ratio of ammonia to hydrogen cyanide in the gas mixture is from 0.06 to 0.99.

4. The method of claim 1 , further comprising, prior to the bringing:
preparing the gas mixture essentially comprising hydrogen cyanide, ammonia, and water according to an Andrussow process from methane, ammonia, and oxygen.

5. The method of claim 1 , further comprising, prior to the bringing:
preparing the gas mixture essentially comprising hydrogen cyanide, ammonia, and hydrogen according to a BMA process from methane and ammonia.

6. The method of claim 1 , further comprising:
separating the product mixture obtained after the bringing in and/or after the bringing into an offgas comprising nitrogen, hydrogen, and/or methane, and a liquid mixture comprising 2-hydroxy-4-(methylthio)butyronitrile, and
optionally purifying the offgas.

7. The method of claim 1 , wherein the product mixture obtained in the bringing further comprises 2-amino-4-(methylthio)butyronitrile and/or 2,2′-bis(2-(methylmercaptoethyl)iminodiacetonitrile.

8. The method of claim 2 , further comprising:
storing the product mixture obtained in the bringing at temperatures no higher than 60° C. and a pH of 2 to 8, before the product mixture is further reacted.

9. The method of claim 2 , further comprising:
first reacting the product mixture obtained in the bringing with ammonia and/or ammonium salts and carbon dioxide and/or carbonic acid salts to give 5-(2-methylmercaptoethyl)hydantoin.

10. The method of claim 9 , further comprising:
second reacting the 5-(2-methylmercaptoethyl)hydantoin under basic conditions, thereby forming carbon dioxide and ammonia, to give at least one methionine salt.

11. The method of claim 10 , further comprising:
at least partially recycling the ammonia and the carbon dioxide from the second reacting to the first reacting.

12. The method of claim 10 , further comprising:
at least partially recycling the ammonia obtained in the second reacting to the preparing.

13. The method of claim 10 , further comprising:
at least partially disposing of the ammonia obtained in the second reacting.

14. The method of claim 2 , further comprising:
purifying the product mixture from the bringing by distillation by removing at least a part of water.

15. The method of claim 12 , further comprising:
freeing the ammonia obtained after the second reacting from sulfur-containing compounds and optionally from CO 2 before it is recycled to the preparing.

16. The method of claim 10 , further comprising:
reacting the at least one methionine salt with an acid to give methionine.

17. A method for preparing a dipeptide of methionine, the method comprising:
carrying out the method of claim 1 , and then, in any order, aminating and hydrolyzing the 2-hydroxy-4-(methylthio)butyronitrile with acid or base to obtain a carboxylic acid;
optionally esterifying the carboxylic acid, to obtain an ester; and
condensing the carboxylic acid and/or the ester to form the dipeptide.

18. A method for preparing 3,6-bis(2′-methylmercaptoethyl)-2,5-diketopiperazine, the method comprising:
carrying out the method of claim 1 , and then, in any order, aminating and hydrolyzing the 2-hydroxy-4-(methylthio)butyronitrile with acid or base to obtain a carboxylic acid;
optionally esterifying the carboxylic acid, to obtain an ester; and
condensing the carboxylic acid and/or the ester to form the 3,6-bis(2′-methylmercaptoethyl)-2,5-diketopiperazine.

19. The method of claim 2 , in which a molar ratio of ammonia to hydrogen cyanide in the gas mixture is from 0.06 to 0.99.

20. The method of claim 2 , further comprising, prior to the bringing:
preparing the gas mixture essentially comprising hydrogen cyanide, ammonia, and water according to an Andrussow process from methane, ammonia, and oxygen.

Assignees

• Evonik Operations Gmbh

Inventors

• Hierold Judith
• Sudhoff Daniel
• Steurenthaler Martin
• Hasselbach Hans Joachim
• Roth Philipp
• Merker Thorsten
• Held Markus
• Fischer Daniel
• Kaiser Christian

Classifications

• C07C323/58 Primary

  with amino groups bound to the carbon skeleton · CPC title

• C01C3/0212

  from hydrocarbons and ammonia in the presence of oxygen, e.g. the Andrussow-process · CPC title

• C07C319/20 Primary

  by reactions not involving the formation of sulfide groups · CPC title

• C07D241/08

  with oxygen atoms directly attached to ring carbon atoms · CPC title

• C07D233/76

  with substituted hydrocarbon radicals attached to the third ring carbon atom · CPC title