ketose's Usage Examples:

These reactions permit the transformation of an aldose into a ketose; the reverse change can only be brought about by reducing the ketose to an alcohol, and oxidizing this compound to an aldehyde.

The configurations of the pentaand tetra-aldoses have been determined by similar arguments; and those of the ketoses can be deduced from the aldoses.

Of the ketoses, we notice d-sorbose, found in the berries of mountain-ash, and d-tagatose, obtained by Lobry de Bruyn and van Ekenstein on treating galactose with dilute alkalis, talose and l-sorbose being formed at the same time.

The ketone is also obtained when Bertrand's sorbose bacterium acts on glycerol; this medium also acts on other alcohols to yield ketoses; for example: erythrite gives erythrulose, arabite arabinulose, mannitol fructose, 'c.

The osazone prepared from a-acrose resembled most closely the glucosazone yielded by glucose, mannose, and fructose, but it was optically inactive; also the ketose which it gave after treatment with hydrochloric acid and reduction of the osone was like ordinary fructose except that it was inactive.

It is seen that aldoses and ketoses which differ stereochemically in only the two final carbon atoms must yield the same osazone; and since d-mannose, d-glucose, and d-fructose do form the same osazone (d-glucosazone) differences either structural or stereochemical must be placed in the two final carbon atoms.

On warming the osazone with hydrochloric acid the phenylhydrazine residues are removed and an osone results, which on reduction with zinc and acetic acid gives a ketose.

ketose ribulose-5-phosphate.

d-Erythrulose is a ketose of this series.

It is found also that some monosaccharoses behave as aldehydes whilst others contain a keto group; those having the first character are called aldoses, and the others ketoses.

l-Arabinulose obtained from arabite and Bertrand's sorbium bacterium is a ketose.

A ketose may also be obtained by reducing the osazone with zinc and acetic to an osamine, which with nitrous acid gives the ketose: R R R C :N NHPh.