Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2006-08-15
2006-08-15
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S186000
Reexamination Certificate
active
07091375
ABSTRACT:
The invention relates to a method for producing 2-keto-L-gulonic acid-C4–C10alkyl ester by esterifying 2-keto-L-gulonic acid (KGS) with an unsaturated, branched or unbranched C4–C10alcohol. The inventive method is characterized by the fact that an aqueous KGS solution is reacted with a C4–C10alcohol 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–C10alcohol 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.
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Domschke Thomas
Faust Tillmann
Grossmann Georg
Merger Martin
BASF - Aktiengesellschaft
Carr Deborah D.
Connolly Bove & Lodge & Hutz LLP
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