Isolation of ketoses or nonreducing sugars from a sugar mixture containing aldoses by aniline treatment

A method for the isolation of ketoses and nonreducing sugars from sugar mixtures by the addition of aniline, in the presence of acetic acid as a catalyst, is described. The aldoses react readily to form aniline derivatives, which are then removed using standard procedures: extraction with organic solvents, and treatment with activated charcoal and with a cation-exchange resin. The ketoses and nonreducing sugars are retained in aqueous solution.