Method for producing L-ascorbic acid by lactonization of 2-keto-L-gulonic acid or 2-keto-L-gulonic acid esters

摘要

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.