Merck Patent Gesellschaft MIT Beschrankter Haftung

Rolf Wittmann

Jurgen Butzke

Willi Wintermeyer

Fritz Reiff

Peter Muller

Rudolf Wolf

A process is provided for separating and recovering solid, metal catalysts from reaction mixtures in which they are dispersed, with cross-flow filtration using membrane separation devices. The process is particularly useful for separating gelatinous catalyst sludges, e.g., nickel hydroxide, used in oxidizing diacetone sorbose.

Process for separating and recovering metal catalysts

A process for preparing diacetoneketogulonic acid comprises oxidizing diacetonesorbose in two or more oxidizing steps using different oxidizing agents in each step. In preferred embodiments the first oxidation is done electrochemically or using air and the second oxidation is via hypochlorite treatment.

Preparation of diacetoneketogulonic acid by oxidation of diacetonesorbose

A process for preparing diacetone-ketogulonic acid comprises oxidizing diacetonesorbose to diacetone-ketogulonic acid to an extent of about 30-95% by electrochemical oxidation or O.sub.2 oxidation; electrodialysing the resultant reaction solution to separate the pure diacetoneketogulonic acid from the unoxidized diacetonesorbose; and recycling the unoxidized diacetone-sorbose to the oxidation step.

Preparation of diacetone-ketogulonic acid

A process is provided for preparing riboflavin from D-glucose in good yield and under efficient conditions.

Process for the preparation of riboflavin

Diacetone-2-ketogulonic acid is prepared by electrochemical oxidation of diacetone-sorbose in an aqueous alkaline medium in the presence of 0.001 to 1% of surfactant.

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Muhltal, Germany

Rolf Wittmann