Degussa Aktiengesellschaft

Degussa - Huls Ag

Volker Hafner

Klaus Huthmacher

Harald Heinzel

Hans Joachim Hasselbach

Helmut Suchsland

Hans Albrecht Hasseberg

Axel Kleemann

Steffen Krill

Horst Weigel

Georg Markowz

Herbert Tanner

Hans-Joachim Hasselbach

Axel Ronneburg

Nongyuan Shi

Hans-Albrecht Hasseberg

Barbara Jager

Hans-Albrechl Hasseberg

A process for the production of 2,3,5-trimethylhydroquinone diesters by aromatization of 2,6,6-trimethyl-2-cyclohexene-1,4-dione (4-oxoisophorone, ketoisophorone, KIP) with an acylating agent and an acidic soluble or insoluble catalyst, which process may be operated alternatively continuously or discontinuously. The process includes the following steps: a) a carboxylic anhydride having a C,to C,alkyl residue is used as the acylating agent, b) after the reaction, a proportion of the resultant carboxylic acid is optionally removed by distillation, c) the reaction solution is cooled, d) the product which has crystallized out is separated and washed, and e) the filtrate is returned to step a).

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

A process is provided for the recovery of sulfuric acid from NH.sub.4 HSO.sub.4 and (NH.sub.4).sub.2 SO.sub.4 salts produced from the sulfuric acid hydrolysis of methylmercaptopropionaldehyde (MMP) cyanohydrin to produce 2-hydroxy-4-methylthiobutyric acid (MHA), which can be used as an additive in animal feed. The sulfate salts are combusted in a furnace to produce sulfur dioxide; the sulfur dioxide is contacted with an aqueous solution containing sulfuric acid and hydrogen peroxide, where the sulfur dioxide is converted into sulfuric acid. The product sulfuric acid is recovered.

Method for recovering sulfuric acid from sulfate salts

Process for obtaining 2-hydroxy-4-methylthiobutyric acid (MHA)

A method for obtaining 2-hydroxy-4-methylthiobutyric acid (methionine-hydroxy analog, MHA) in primarily free form which is stable in storage by distilling a product solution containing MHA and by producing MHA product mixtures with improved storage stability from such a distillate. The distillate can be produced directly starting from MHA raw products from any MHA production process, which can optionally also contain solvent or water. The starting material may also be a commercial MHA product.

Method for obtaining 2-hydroxy-4-methylthiobutyric acid (MHA) which is

Process for recovering 2-hydroxy-4-methylthiobutyric acid (MHA), MHA and

Process for producing 2-hydroxy-4-methylthiobutyric acid (MHA) and its

The invention is directed to a process for the production of iminodiacetonitrile by reaction of hexamethylenetetramine with hydrogen cyanide in acidic aqueous mediums. In this process the pH during the reaction which is 5.5 to 7.5 at the beginning is progressively lowered, altogether around 0.5 to 3.5 units and free formaldehyde is present only to a slight extent. Through this and in contrast to the known processes the formation of byproducts is suppressed and iminodiacetonitrile is produced directly in very good yields and sufficiently pure for further use.

Process for the production of iminodiacetonitrile

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Langenselbold, Germany

Volker Hafner