Method for the production of D,L-methionine

Patent metadata

Field	Value
Publication number	US-9206121-B2
Application number	US-201514671435-A
Country	US
Kind code	B2
Filing date	Mar 27, 2015
Priority date	Feb 23, 2011
Publication date	Dec 8, 2015
Grant date	Dec 8, 2015

Abstract

A method to produce D,L-Methionine from 2-hydroxy-4-(methylthio)butyronitrile by reaction with ammonia, optionally in the presence of carbon dioxide, is provided. The 2-hydroxy-4-(methylthio)butyronitrile is obtained by reaction of 3-methylmercaptopropionaldehyde with hydrogen cyanide in the presence of a base as catalyst in a main reaction zone of a multizone reactor. Residual gaseous hydrogen cyanide is removed from the main reaction zone to an absorption and post-reaction zone of the reactor which comprises a mixture of 3-methylmercaptopropionaldehyde and the catalyst; and the gaseous hydrogen cyanide is further reacted with the 3-methylmercaptopropionaldehyde in the absorption and post reaction zone. A molar ratio of hydrogen cyanide to 3-(methylthio)propanal in the main reaction zone is from 0.98 to 1.03.

First claim

The invention claimed is:

1. A process for producing D,L-methionine, the process comprising:
conversion of 2-hydroxy-4-(methylthio)butyronitrile to the D,L-methionine by reaction with ammonia, optionally in the presence of carbon dioxide;
wherein
the 2-hydroxy-4-(methylthio)butyronitrile is obtained by a process comprising:
reacting 3-methylmercaptopropionaldehyde with hydrogen cyanide in the presence of a base as catalyst in a main reaction zone of a multizone reactor to form a reaction mixture comprising the 2-hydroxy-4-(methylthio)butyronitrile, unreacted 3-methylmercaptopropionaldehyde, the catalyst and residual amounts of gaseous hydrogen cyanide;
removing the residual gaseous hydrogen cyanide from the main reaction zone to an absorption and post-reaction zone of the reactor which comprises a mixture of 3-methylmercaptopropionaldehyde and the catalyst;
further reacting the gaseous hydrogen cyanide with the 3-methylmercaptopropionaldehyde in the absorption and post reaction zone; and
removing the 2-hydroxy-4-(methylthio)butyronitrile from the multizone reactor.

2. The process according to claim 1 , wherein a pH of the reaction mixture in the main reaction zone of the 3-methylmercaptopropionaldehyde hydrogen cyanide reaction and the absorption and post-reaction zone is 4.5 to 6.0, as measured with a pH electrode at 23° C. and a water content of 2 to 14% by weight.

3. The process according to claim 1 , wherein the main reaction zone comprises a jet pump and the jet pump mixes a hydrogen cyanide feed gas with the reaction mixture.

4. The process according to claim 1 , wherein the absorption and post-reaction zone comprises a device for contacting a gas with a liquid, the device being at least one selected from the group consisting of a column, a tray column, a packed-bed column, a bubble-column reactor, a droplet column, a reactor having a mechanically agitated container, a submerged jet reactor and a jet pump.

5. The process according to claim 1 , wherein the catalyst is selected from the group consisting of a low-molecular-weight amine, a heterogeneous amine, a solution of an inorganic base, and a mixture of an acid and a low-molecular-weight amine.

6. The process according to claim 5 , wherein the catalyst is a low-molecular-weight amine, which is selected from the group consisting of a tri-(C 1 -C 12 -alkyl)amine, a dialkylaralkylamine, a dialkylarylamine and a heterocyclic amine.

7. The process according to claim 6 , wherein the catalyst is a polyvinylpyridine or a heterogeneous amine which is of formula (I)

wherein
R 1 and R 2 are each independently hydrogen, C 1 to C 12 alkyl, aryl or heteroaryl;
X is a number between 0 and 6, and
A is a natural or synthetic resin.

8. The process according to claim 7 , wherein the catalyst is a heterogeneous amine of formula I and is a polymer-bound base selected from the group consisting of homologous dialkylaminoalkylpolystyrenes and dialkylaminomacroreticular resins.

9. The process according to claim 8 , wherein the catalyst of formula I is at least one selected from the group consisting of diethylaminoethylpolystyrene, diethylaminomethylpolystyrene, dimethylaminomethylpolystyrene, diethylaminomethylmacroreticular resin and dimethylaminoethylpolystyrene.

10. The process according to claim 5 , wherein the catalyst is an inorganic base which is at least one selected from the group consisting of an alkali metal hydroxide, an alkali metal cyanide, an alkali metal carbonate, and an alkali metal hydrogencarbonate.

11. The process according to claim 5 , wherein the catalyst is a mixture of an acid and a low-molecular-weight amine and the acid is at least one selected from the group consisting of organic carboxylic acids, organic sulfonic acids and mineral acids.

Assignees

• Buss Dieter
• Steurenthaler Martin
• Rinner Michael R
• Kretz Stephan
• Hasselbach Hans Joachim
• Finkeldei Caspar-Heinrich
• Koerfer Martin
• Zacchi Pablo
• Evonik Degussa Gmbh

Inventors

• Buss Dieter
• Steurenthaler Martin
• Rinner Michael R
• Kretz Stephan
• Hasselbach Hans Joachim
• Finkeldei Caspar-Heinrich
• Koerfer Martin
• Zacchi Pablo

Classifications

• C07C319/20 Primary

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

• C07C323/52

  the carbon skeleton being acyclic and saturated · CPC title

• C07C323/58

  with amino groups bound to the carbon skeleton · CPC title

• C07C323/60

  with the carbon atom of at least one of the carboxyl groups bound to nitrogen atoms · CPC title

• C07C255/12 Primary

  containing cyano groups and hydroxy groups bound to the carbon skeleton · CPC title