Dsm Chemie Linz Gmbh

Dsm Fine Chemicals Austria Gmbh

Curt Zimmermann

Karlheinz Giselbrecht

Johann Friedhuber

Kurt Weissenbock

Process for transesterifying &agr;-ketocarboxylic esters in an anhydrous alcohol as reaction medium in the presence of tin catalysts, titanium catalysts, zirconium catalysts or lithium catalysts or of acetylacetonates as catalysts.

Process for transesterifying &agr;-Ketocarboxylic esters

Process for preparing N-pyruvyl-L-proline by reaction of L-proline with methyl pyruvate dimethyl ketal in the presence of an alkali metal alkoxide, subsequent acid hydrolysis and extraction of 1-pyruvyl-L-proline.

Process for preparing 1-pyruvyl-L-proline

A process for preparing high-purity calcium pyruvate or its hydrates by reacting an aqueous solution of pyruvic acid with an inorganic calcium compound with the pH being set to 2 to 7, preferably 2.5 to 4, which comprises reacting an up to 10% strength aqueous solution of pyruvic acid with the calcium compound, in the presence or absence of a stabilizer or complexing agent, and mixing the resulting solution with an organic diluent at temperatures of 0.degree. to 30.degree. C. and isolating the resulting precipitate of calcium pyruvate or its hydrate from the solution.

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Mauthausen, Austria

Curt Zimmermann