Method for the production of L-ascorbic acid by lactonization of 2-keto-L-gulonic acid or s2-keto-L-gulonate esters
AssigneeBASF SE
InventorsAndreas Böttcher, Wolfram Burst
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Abstract
The invention relates to a process for the preparation of L-ascorbic acid, in which free 2-keto-L-gulonic acid or C3-C10-alkyl 2-keto-L-gulonate is lactonized under acidic conditions in the presence of a water-miscible solvent and where this solvent in situ forms a solvent in which the ascorbic acid formed is poorly soluble.
Claims16
A process for the preparation of L-ascorbic acid, which comprises lactonizing 2-keto-L-gulonic acid or a melt of C3-C6-alkyl 2-keto-L-gulonate with acid catalysis in the presence exclusively of a solvent or solvent mixture which is miscible with water and in situ forms a solvent in which the ascorbic acid formed is poorly soluble.
A process for the preparation of L-ascorbic acid, which comprises the following steps:
- a) esterification of 2-keto-L-gulonic acid or 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid with a C3-C6-alcohol in the presence of an acidic catalyst,
- b) distillation of the excess C3-C6-alcohol together with the water of reaction formed and
- c) lactonization of the C3-C6-alkyl 2-keto-L-gulonate formed with acid catalysis in the presence exclusively of a solvent or solvent mixture which is miscible with water and in situ forms a solvent in which the ascorbic acid formed is poorly soluble.
Dependencies are inferred from the claim text.