Basf Aktiengesellschaft

Basf Se Corporation

Tillmann Faust

Jochem Henkelmann

Alois Kindler

Harald Rust

Kirsten Burkart

Christian Knoll

Andre Mohry

Karl-Heinz Etzbach

Reinhold J Leyrer

Karl Siemensmeyer

Harald Keller

Peter Schuhmacher

Thomas Subkowski

Martin Merger

Johannes Grimmer

Michael Schönherr

Joachim Meyer

Christoph Martin

Michael Becker

Thomas Domschke

Georg Grossmann

Georg Wellinghoff

Walter Gosele

Ulrike Richter

The invention relates to a method for producing 2-keto-L-gulonic acid-C&#x2013;Calkyl ester by esterifying 2-keto-L-gulonic acid (KGS) with an unsaturated, branched or unbranched C&#x2013;Calcohol. The inventive method is characterized by the fact that an aqueous KGS solution is reacted with a C&#x2013;Calcohol up to an esterification degree of 20 to 70 percent in a pre-esterification process carried out under acidic catalysis conditions; and the obtained product is dehydrogenated with an unsaturated, branched or unbranched C&#x2013;Calcohol in a continuous rectification device, whereby the esterification reaction continues, n-butanol preferably being used as the alkyl alcohol. In a preferred embodiment, the aqueous KGS solution is concentrated up to or beyond the limit of solubility prior to the esterification process, preferably by catalyzing a homogeneous or heterogeneous catalyst, especially sulfonic acid, at temperatures of 50 to 120&#xb0; C. In another embodiment, the produced KGS ester is reacted in one or several additional steps so as to obtain L-ascorbic acid.

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The present invention relates to a process for continuously preparing 5-alkoxy-substituted oxazoles, in particular for continuously preparing 4-methyl-5-alkoxy-substituted oxazoles and also a process for preparing pyridoxine derivatives.

Continuous preparation of substituted oxazoles

The present invention relates to a process for preparing 5-alkoxy-substituted oxazoles, in particular for preparing 4-methyl-5-alkoxy-substituted oxazoles and also a process for preparing pyridoxine derivatives.

Process for the preparation of substituted oxazoles

Process for producing pigment particles of defined shape and size

Riboflavin is removed from fermentation suspensions by them being heated at from 50.degree. to 90.degree. C. for from 1 to 3 hours, than cooled to from 0.degree. to 30.degree. C. over a period of from 1 to 5 hours, and subsequently being centrifuged to give a sediment fraction and liquid fraction in such a way that the sediment fraction contains predominantly riboflavin crystals as solid, and the liquid fraction contains virtually no crystalline riboflavin, and, where appropriate, resuspending the sediment fraction in from 0.5 to 2 parts by volume of water per part by volume of sediment fraction and repeating procedure c.

Removal of riboflavin from fermentation suspensions

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Weisenheim, Germany

Tillmann Faust