The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 13, 2015
Filed:
Feb. 26, 2013
Martin Koerfer, Kahl, DE;
Hans Joachim Hasselbach, Gelnhausen, DE;
Stefan Reichert, Frankfurt, DE;
Harald Jakob, Hasselroth, DE;
Christoph Weckbecker, Gruendau, DE;
Klaus Huthmacher, Gelnhausen, DE;
Horst Krull, Hanau, DE;
Bernd Drapal, Alzenau, DE;
Rainer Peter, Krombach, DE;
Martin Koerfer, Kahl, DE;
Hans Joachim Hasselbach, Gelnhausen, DE;
Stefan Reichert, Frankfurt, DE;
Harald Jakob, Hasselroth, DE;
Christoph Weckbecker, Gruendau, DE;
Klaus Huthmacher, Gelnhausen, DE;
Horst Krull, Hanau, DE;
Bernd Drapal, Alzenau, DE;
Rainer Peter, Krombach, DE;
EVONIK INDUSTRIES AG, Essen, DE;
Abstract
The invention relates to a process for the preparation of D,L-methionine, in which carbon dioxide is fed to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified, where, for the purposes of purification, an aqueous solution of the separated-off crude methionine is prepared and subjected to a recrystallization, characterized in that the solution from which the recrystallization takes place contains potassium ions and also a crystallization additive, where the crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants, and that the recrystallization takes place by introducing a 60 to 110° C.-hot methionine solution into a 35 to 80° C.-warm methionine suspension, the temperature of which is lower than that of the introduced solution, the temperature of the methionine suspension being maintained between 35 and 80° C. during the addition.