Process for the preparation of D,L-methionine or the salt thereof

US5770769A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Friedhelm Geiger · Bethlehem, US
• Baudouin Halsberghe · Mobile, US
• Hans Joachim Hasselbach · Gelnhausen, DE
• Klaus Hentschel · Rodenbach, DE
• Klaus Huthmacher · Gelnhausen, DE
• Martin Körfer · Goldbach, DE
• Sven-Peter Mannsfeld
• Herbert Tanner
• Ferdinand Theissen · Hanau, DE
• Jose Vanrobaeys · Mobile, US
• Klaus Willigerodt · Mobile, US

Key dates

• Filing date: Dec 18, 1996
• Grant date: Jun 23, 1998
• Expiry date: Dec 18, 2016

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D233/76
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of methionine or a salt of methionine by reaction of the components 3-methylmercaptopropionaldhyde, hydrogen cyanide, ammonia and carbon dioxide or components from which the above-mentioned components can be prepared, optionally in the presence of water, to 5-(2-methylmercaptoethyl)-hydantoin and further reaction thereof to methionine or the salt thereof, characterised in that the reaction of the components is initiated by means of at least one premixture in such a way that a first mixture is formed containing at least the predominant proportion (at least 5/10) of the 3-methylmercaptopropionaldeyde and at least 1/10 of the hydrogen cyanide component or corresponding quantities of components from which these components can be prepared, and less than 5/10 of one of the components ammonia, carbon dioxide or of the components from which ammonia or carbon dioxide can be prepared, and in that this first mixture is combined with the other component(s) for the reactive conversion to 5-(2-methylmercaptoethyl)-hydantoin, wherein this (these) latter component(s) may be premixed in one or more other mixtures.