Degussa Aktiengesellschaft

Evonik Operations Gmbh

Evonik Degussa Gmbh

Degussa - Huls Ag

Evonik Industries Ag

Bernd Drapal

Klaus Huthmacher

Rainer Peter

Harald Jakob

Steffen Krill

Hans Joachim Hasselbach

Nongyuan Shi

Stefan Reichert

Christoph Weckbecker

Martin Koerfer

Hans-Joachim Hasselbach

Horst Krull

Mario Scholz

Horst Weigel

Steffen Hasenzahl

Herbert Tanner

Frank Hubner

Ralph McIntosh

Imad Moussallem

Hermann Schmitt

Martin Körfer

Christian Renner

Christian Kaiser

Benny Hartono

Sebastian Bernhardt

Danny De Corte

Markus Julino

Frank H&uuml;bner

Christoph Weckenbecker

Tobias Winkler

Johannes Wefer

Christian Rückriegel

Christian RÜCKRIEGEL

The invention relates to a single cycle process for preparing D,L-methionine from an alkali methioninate solution obtained by alkaline hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in which the D,L-methionine is obtained by neutralizing the alkali methioninate solution with carbon dioxide at elevated temperature and subsequently crystallizing D,L-methionine in the presence of seed crystals.

Process for the preparation of D,L-methionine

A process for preparing methionine includes the alkaline hydrolysis of 5-(2-methylmercaptoethyl)-hydantoin (methionine hydantoin) in an aqueous process solution containing alkali metal hydroxide and/or alkali metal carbonate and/or alkali metal hydrogencarbonate. The alkali metal cations in the process solution are potassium and sodium having a K/Na molar ratio range from 99/1 to 20/80.

Process for preparing methionine

This disclosure relates to a process for preparing D,L-methionine by feeding carbon dioxide 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. In this process an aqueous solution of the separated-off crude methionine is purified by recrystallization from a solution containing potassium ions and also a crystallization additive. The crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants. The recrystallization occurs by introducing a 60 to 110&#xb0; C.-hot methionine solution into a 35 to 80&#xb0; C.-warm methionine suspension, a temperature of which is lower than that of the introduced solution, such that the temperature of the methionine suspension being maintained between 35 and 80&#xb0; C. during the addition. The crystallization additive is a sorbitan fatty acid ester or a mixture of different sorbitan fatty acid esters.

Process for the preparation of methionine

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&#xb0; C.-hot methionine solution into a 35 to 80&#xb0; 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&#xb0; C. during the addition.

A process for the preparation of &bgr;,&ggr;,&dgr;-unsaturated ketones and/or &agr;,&bgr;,&ggr;,&dgr;-unsaturated ketones by the reaction of an unsaturated alcohol with an enol ether or mixture of enol ethers, with formation of ketals as a by-product, at temperatures of from 50&deg; C. to 200&deg; C., in the presence of an acid catalyst, whereby one or all of the reagents is/are heated to the reaction temperature of from 50&deg; C. to 200&deg; C. before the acid catalyst is added.

Process for the preparation of unsaturated ketones

Process for the preparation of unsaturated 4,5-allene ketones by reaction of tertiary propargyl alcohols with alkenyl alkyl ethers or ketals in the presence of aliphatic sulfonic acids or sulfonic acid salts.

Process for the preparation of unsaturated 4,5-allene ketones, 3,5-diene ketones and the corresponding saturated ketones

Preparation of 2,3,5-trimethylhydroquinone diesters by rearrangement of 2,6,6-trimethylcyclohex-2-ene-1,4-dione (4-oxo-isophorone, ketoisophorone) in the presence of a solid, acid catalyst and an acylating agent, for example carboxylic acid anhydrides or carboxylic acid halides. The 2,3,5-trimethylhydroquinone diester may then optionally be saponified to the free 2,3,5-trimethylhydroquinone, which is a valuable building block in the synthesis of vitamin E.

Process for the preparation of 2,3,5-trimethylhydroquinone diesters

The invention relates to an improved method for the production of 2,3,5-trimethylhydroquinone by rearranging 4-oxo-isophorone (keto-isophorone, 3,5,5-trimethylcyclohex-2-en[e]-1,4-dione) to a trimethylhydroquinone diester and by its subsequent saponification. ##STR1##

Method for the production of trimethylhydroquinone

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Alzenau, Germany

Bernd Drapal