Method for the production of 2=-keto-l-gulonic acid C4C10 alkyl esters

US7091375B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Thomas Domschke · Speyer, DE
• Martin Merger · Bischofswerda, DE
• Georg Grossmann · Mannheim, DE
• Tillmann Faust · Bad Dürkheim, DE

Key dates

• Filing date: Nov 7, 2003
• Grant date: Aug 15, 2006
• Expiry date: Nov 7, 2023

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P20/10
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing 2-keto-L-gulonic acid-C4–C10 alkyl ester by esterifying 2-keto-L-gulonic acid (KGS) with an unsaturated, branched or unbranched C4–C10 alcohol. The inventive method is characterized by the fact that an aqueous KGS solution is reacted with a C4–C10 alcohol 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 C4–C10 alcohol 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° C. In another embodiment, the produced KGS ester is reacted in one or several additional steps so as to obtain L-ascorbic acid.