noun
definition
A sugar or saccharide containing five carbon atoms.
example
Ribose, found in RNA, is a common pentose
Examples of pentoses in a Sentence
Four active tetroses are possible, and three have been obtained by Ruff and Wohl from the pentoses.
The first term includes simple sugars containing two to nine atoms of carbon, which are known severally as bioses, trioses, tetroses, pentoses, hexoses, &c.; whilst those of the second group have the formula C12H22011 and are characterized by yielding two monosaccharose molecules on hydrolysis.
We may notice that the pentoses differ from other sugars by yielding furfurol when boiled with hydrochloric acid.
Rhamnose or isodulcite, a component of certain glucosides, fucose, found combined in seaweeds and chinovose, present as its ethyl ester, chinovite, in varieties of quina-bark, are methyl pentoses.
To settle this point it is necessary to consider the configuration of the isomeric pentoses - arabinose and xylosefrom which they may be prepared.
If the asymmetric system adjoining the COH group, which is that introduced in synthesizing the hexose from the pentose, be eliminated, the formulae at disposal for the two pentoses are CH 2 (OH) - - - COH CH 2 (OH)+-- COH.
Hence it follows that the " optical " formulae of the acids derived from two pentoses having the configuration given above will be C02H - 0 - C02H CO 2 H + 0 - C02H, and that consequently only one of the acids will be optically active.