Sialic Acids and Related Substances

N-Acetyl-D-galactosamine, N-acetyl-D-mannosamine and N-acetyl-D-glucosamine were allowed to react with oxalacetic acid under alkaline conditions, and the condensation products purified by ion-exchange chromatography. Properties of these products on the whole are similar to each other, though there is a minor but significant diference in the condensation product with N-acetyl-D-galactosaminc. Paper chromatograms of the condensation products suggest that N-acetyl-D-galactosamine as well as N-acetyl-D-glucosamine are epimerized partly before they condense with oxalacetic acid to givc each two sialic acids with different configurations at C-5 from each other.