# US 4,391,987 A · Process for the production of aqueous sodium methioninate solutions

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- Number: US 4,391,987 A
- Document ID: US4391987A
- Status: Granted
- Kind: A
- Application number: 06/347,473
- Filed: 1982-02-10
- Granted: 1983-07-05
- Earliest claimed: 1981-02-12
- Assignees: Degussa AG
- Inventors: Manfred Spindler; Herbert Tanner; Friedhelm Geiger; Friedrich Bittner; Jurgen Martens
- Web page: https://patentgrep.com/patent/US4391987A

## CPC

- A23K 20/142: Amino acids; Derivatives thereof
- A23K: FODDER

## Abstract

Aqueous sodium methioninate solutions having a low content of sodium carbonate can be recovered from the crude hydrolysis mixture resulting from the saponification of 5-(.beta.-methylmercaptoethyl)hydantoin with 1.1 to 6 equivalents of sodium hydroxide and/or sodium carbonate by cooling the crude hydrolysis mixture to a temperature below 10.degree. C., separating off the precipitated sodium carbonate and concentrating the sodium methioninate solution remaining to 40 to 65 weight percent.

## Claims

### Claim 1

A process for the production of an aqueous sodium methioninate solution having a low content of sodium carbonate comprising forming a crude aqueous hydrolysis mixture by the saponification of 5-(.beta.-methylmercaptoethyl)-hydantoin with 1.1 to 6 equivalents of sodium hydroxide, sodium carbonate or a mixture of sodium hydroxide and sodium carbonate, cooling the crude hydrolysis mixture to a temperature below 10.degree. C., separating off the precipitated sodium carbonate and concentrating the sodium methioninate solution remaining to 40 to 65 weight percent.

### Claim 2 (depends on 1)

A process according to claim 1 wherein the step of cooling the crude hydrolysis mixture prior to the separation of sodium carbonate is to a temperature between -10.degree. and +5.degree. C.

### Claim 3 (depends on 2)

A process according to claim 2 wherein the saponification is carried out with sodium hydroxide.

### Claim 4 (depends on 1)

A process according to claim 1 wherein the saponification is carried out with sodium hydroxide.

### Claim 5 (depends on 1)

A process according to claim 1 wherein the sodium carbonate separated off contains a minor amount of sodium methioninate as impurity and this impure sodium carbonate is treated with sodium hydroxide and/or sodium carbonate in an amount sufficient to provide 1.1 to 6 equivalents of sodium carbonate or a mixture of sodium carbonate and sodium hydroxide per equivalent of 5-(.beta.-methylmercaptoethyl)-hydantoin and the thus treated sodium carbonate is recycled to saponify more 5-(.beta.-methylmercaptoethyl)-hydantoin.

### Claim 6 (depends on 5)

A process according to claim 5 wherein the step of cooling the crude hydrolysis mixture before the separation of sodium carbonate is to a temperature between -10.degree. and +5.degree. C.

### Claim 7 (depends on 1)

A process according to claim 1 consisting of the recited steps employing the recited materials.

### Claim 8 (depends on 2)

A process according to claim 2 consisting of the recited steps employing the recited materials.

### Claim 9 (depends on 5)

A process according to claim 5 consisting of the recited steps employing the recited materials.

### Claim 10 (depends on 6)

A process according to claim 6 consisting of the recited steps employing the recited materials.