Xylose

Wood sugar

• 58-86-6 (D - shape )
• 609-06-3 ( L-form)
• 25990-60-7 (racemate )

Colorless, sweet-tasting needles or prisms

Fixed

154-158 ° C ( both enantiomers)

Well in water, soluble in hot ethanol and pyridine

Template: Infobox chemical / molecular formula search available

Xylose ( xylose, molecular formula C5H10O5 ) is an aldopentose, a type of sugar with five carbon atoms and an aldehyde group as a functional group, which results among other things in the hydrolysis of wood rubber with dilute acids. The sugar substitute xylitol is produced from it. Based on sucrose has a 10% D- xylose a sweetening power of 67%. Xylose is not degradable in the body and excreted in unaltered form. In medicine, xylose is therefore used in the intestine for the study of gastric emptying and resorption.

The CAS number for the open-chain, racemic xylose is 25990-60-7. Each ring shape and each stereoisomer is assigned a unique CAS number:

Stereochemistry

The term xylose represents two enantiomers: D- xylose and L -xylose, which relate to each other as mirror images. The position of the hydroxyl group at C4 ( the second lowest carbon atom) determines whether it is D- or the L-enantiomer is the. In the Fischer projection shows this in the D -xylose to the right ( Latin: dexter, therefore D), in which L -xylose to the left ( Latin: laevus, L). As well as other long-chain sugars, xylose can react intramolecularly to form a cyclic hemiacetal of five or six atoms in the ring. Due to the thus emerging chiral center, there are four isomers of the ring forms of D- and L- xylose.

The suffixes - pyranose or furanose - describe the similarity of the ring with heterocycles pyran or furan.

At 20 ° C is dissolved in water, similar to D- xylose, D-glucose in 35% of the α - pyranose form and 65 % in the β - pyranose form before.

Medical use

The D -xylose absorption test can be found in the investigation of malabsorption use.