Degussa Aktiengesellschaft

Degussa - Huls Ag

Deutsche Gold- Und Silber-scheideanstalt Vormals Roessler

Degussa Dental Gmbh & Co. Kg

Evonik Degussa Gmbh

Horst Weigel

Klaus Huthmacher

Axel Kleemann

Jurgen Martens

Hans Joachim Hasselbach

Christoph Weckbecker

Steffen Krill

Nongyuan Shi

Frank Hubner

Karlheinz Drauz

Klaus Deller

Gerd Schreyer

Mario Scholz

Herbert Klenk

Steffen Hasenzahl

Wolfgang Leuchtenberger

Georg Markowz

Paul Scherberich

Wolfgang Merk

Horst Bethge

Stephan Rautenberg

Hans-Joachim Hasselbach

Axel Ronneburg

Ralph McIntosh

Dieter Buss

Bernd Drapal

Volker Hafner

Rainer Hahn

Heinrich Petsch

Hans-Albrecht Hasseberg

Axel Kleeman

Regina Steigerwald

Eberhard Busker

Katja Kelm

Herbert Offermanns

Martin K&ouml;rfer

Martin Körfer

A manganese dioxide catalyst for hydrolysing organic nitrites which bear readily oxidizable groups such as thiol or thioether groups to the corresponding carboxamides, and to a process for preparing the catalyst and to its use for hydrolysing organic nitrites.

Manganese dioxide catalyst for the hydrolysis of carbonitriles

A process for preparing 2-hydroxy-4-methylthiobutyric acid ammonium salt involves reacting 3-methylthiopropionaldehyde with hydrogen cyanide to form 2-hydroxy-4-methylthiobutyronitrile, and subsequently hydrolyzing the 2-hydroxy-4-methylthiobutyronitrile by catalytic hydrolysis to form the ammonium salt of the 2-hydroxy-4-methylthiobutyric acid in a single process step. One catalyst may be used in the hydrolysis for the whole reaction. The catalyst is preferably a solid containing a titanium compound such as, e.g., titanium nitride, titanium sulfide or titanium dioxide. The 2-hydroxy-4-methylthiobutyric acid ammonium salt produced by this process is nutritional and can be used as an additive in feedstuffs.

Process for the production of 2-hydroxy-4-methythiobutyric acid ammonium salt

A process for the preparation of &agr;-amino acids by hydrolysis of hydantoins in the presence of water and at least one metallic oxide under conditions such that all the starting materials are completely dissolved in the water as a result of high pressure and high temperature and only one further phase is present in the reactor in addition to the metallic oxide phase.

Process for the preparation of alpha-amino acids by hydrolysis of hydantoins at elevated pressure and elevated temperature

Hydrolysis of acylamino acids

A process for preparing esterified chroman compounds from 2,6,6-trimethylcylohex-2-ene-1,4-dione, wherein the esterified intermediates are reacted directly to give the desired chroman derivatives without an additional purification step.

Process for preparing esterified chroman compounds

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

Aliphatic alkanals with a water content of greater than 300 ppm which are stable in storage, and a method of improving the storage stability of these aliphatic alkanals, especially of substituted, sulfur-containing alkanals. The formation of oligomers, polymers and condensation products from elimination reactions and oxidation and the subsequent reactions of the products formed results in undesired impurities that are largely prevented by the addition of an organic acid that forms metal complexes and, optionally, alkanolamines or trialkanolamines.

Aliphatic alkanals with improved storage stability and method of

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

A process for the production of .alpha.-tocopherol esters, derivatives or homologs thereof of the general formula ##STR1## in which the mono- or diester of a hydroquinone is reacted with an allyl alcohol derivative or an allyl alcohol in the presence of zinc halides and proton-liberating acids at a temperature of 25.degree. to 100.degree. C.

Process for the production of .alpha.-tocopherol esters

An improved process for the production of 2,3,5-trimethylhydroquinone by rearrangement of 4-oxoisophorone (ketoisophorone, 3,5,5-trimethyl-2-cyclohexen-1,4-dione) to yield a trimethylhydroquinone diester and the subsequent saponification thereof. Trimethylhydroquinone is in turn an important starting material for the production of vitamin E.

Process for the production of trimethylhydroquinone diesters and of

Method for the continuous preparation of methionine or methionine

Aqueous solutions of free, neutral .alpha.-amino acids are recovered from aqueous solutions of their alkali-metal salts. Two equally large rectifying columns filled with a strongly acidic cation exchanger in the H.sup.+ form are used, the discharge of the first column being connected to the head of the second column. The solution of the alkali-metal salt is at first delivered to the head of the first column, then the residual solution, reduced by the alkali-metal cations adsorbed in the exchanger, is displaced to the second column by means of the addition of water. A product-free forerun is first separated at the discharge of the second column and, when free .alpha.-amino acid begins to exit in the flow-off from the second column, the receiver is changed and the delivery of water to the head of the first column continues further until a mixed pH between 5 and 7 has been achieved in the receiver. Then, the previously first column is decoupled and regenerated, the previously second column, which is now the first column, is coupled to a freshly regenerated column as second column and the entire process is repeated as often as desired.

Method for the recovery of aqueous solutions of free, neutral

Pure L-leucine is obtained from an aminoacid mixture which contains at least 45 weight percent L-leucine, at most 40 weight percent L-isoleucine and at most 25 weight percent of other aminoacids by acetylating the mixture, precipitating the acetylation product by acidification, subjecting the acetylation product to a saponification by an L-aminoacid acylate until 30 to 95% of the N-acetyl-L-leucine employed is saponified and isolating the L-leucine from the saponification mixture.

Process for obtaining pure L-leucine

The separation of L-leucine and L-isoleucine in aminoacid mixtures containing at least 30 weight percent L-leucine, at most 70 weight percent L-isoleucine and at most 40 weight percent of other aminoacids is accomplished by acetylating the mixture, precipitating the acetylation product by acidification, subjecting the aqueous solution to a saponification by an L-aminoacid acylase until 25 to 95% of the N-acetyl-L-leucine is saponified, crystallizing pure L-leucine from the saponification mixture and separating it off, isolating N-acetyl-L-isoleucine from the mother liquor and saponifying it in known manner to the free aminoacid and isolating the free aminoacid.

Process for the separation of L-leucine and L-isoleucine

The subject matter of the invention is a process for the recovery of S-(carboxymethyl)-(R)-cysteine and S-(carboxymethyl)-(S)-cysteine from a mixture of the two enantiomers. The mixture to be separated is dissolved in water in the presence of sufficient ammonia that the ammonium salt solution formed has a pH between 6 and 9. Then there is brought about in the solution of ammonium salt a state of supersaturation by the addition of seeding crystals of the ammonium salt of one of the two enantiomers, insofar as the starting material contains one of the two enantiomers in excess, the ammonium salt of this enantiomer, the ammonium salt of one of the two enantiomers is brought to crystallization and separated off. Subsequently by addition of seeding crystals of the ammonium salt of the other enantiomers to the remaining mother liquor the ammonium salt of this enantiomer is likewise brought to crystallization and separated off. Finally the respective S-(carboxymethyl)-cysteine is set free from the two ammonium salts.

Process for the recovery of S-(carboxymethyl)-(R)-cysteine and

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Rodenbach, Germany

Horst Weigel