Barium 2-ketolactobionate and the corresponding barium bromide double salt

As a preliminary step in the development of methods for the preparation of 2-ketoaldobionic acids for use in the synthesis of glycosidic derivatives of ascorbic acid, the preparation of 2-ketolactobionic acid has been studied. By oxidation of lactose osone with bromine in the presence of barium carbonate, barium 2-ketolactobionate was obtained and separated in the crystalline state. In addition to the normal barium salt, a double salt containing barium bromide was found. This salt is unique in that it is the first and only crystalline barium bromide salt of a sugar acid reported in the literature. It crystallizes freely and is useful for the separation and identification of 2-ketolactobionic acid.