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Fructose, an example of a ketose. The ketone group is the double-
bonded oxygen.

A ketose is a monosaccharide containing one ketone group per molecule.[1][2]

With three carbon atoms, dihydroxyacetone is the simplest of all ketoses and is the only one having no optical activity. Ketoses can isomerize into an aldose when the carbonyl group is located at the end of the molecule. Such ketoses are reducing sugars.

List of ketoses[edit]

Family tree of D-ketoses up to hexoses: dihydroxyacetone (1); D-erythrulose (2); D-ribulose (3a); D-xylulose (3b); D-psicose (4a); D-fructose (4b); D-sorbose (4c); D-tagatose (4d)

All ketoses listed here are 2-ketones:

Qualitative reaction[edit]

General qualitative reaction for ketoses is Seliwanoff's test.

See also[edit]


  1. ^ Lindhorst, Thisbe K. (2007). Essentials of Carbohydrate Chemistry and Biochemistry (1st ed.). Wiley-VCH. ISBN 3-527-31528-4. 
  2. ^ Robyt, John F. (1997). Essentials of Carbohydrate Chemistry (1st ed.). Springer. ISBN 0-387-94951-8.