Sugars pyranose forms during

There have been several reports of the separation of a- and / -pyranose forms during liquid chromatography of sugars.46-49 Initially, this was regarded as a nuisance, but systematic attempts were later made to improve this separation. At 0°, with 1 4 water-acetonitrile as the eluant, many aldoses were separated into two components.48 Galactose and al-trose showed small peaks probably representing the furanose forms ... 

MUTAROTATION The a- and /T forms of monosaccharides are readily interconverted when dissolved in water. This spontaneous process, called mutarotation, produces an equilibrium mixture of a- and /1-forms in both furanose and pyranose ring structures. The proportion of each form differs with each sugar type. Glucose, for example, exists primarily as a mixture of a- (38%) and j8- (62%) pyranose forms (Figure 7.11). Fructose is predominantly found in the a-and /J-furanose forms. The open chain formed during mutarotation can participate in oxidation-reduction reactions. 

There are two forms of carba-sugar carba-pyranoses and -furanoses. The former, especially the carba-hexopyranoses, have been extensively studied during the past two decades, ever since their derivatives were found in Nature as components of important antibiotics. However, very little is known about carba-furanoses, except for 4a-carba-)3-L-arabinofuranose ... 

During an investigation of the properties of furanoses, Serianni and coworkers6 studied the composition of sugars which cannot form pyranoses. Starting with the aldotetroses6 [p. 36], they studied the 5-deoxypentoses 9 some 5-0-substituted pentoses,9 29 and the 2-pentuloses.12 All these compounds will be discussed in this Section. 

Ether derivatives of two l,4 nhydro sugar derivatives have also been polymerized but both the five and six membered rings open during polymerization and copolymers of furanose and pyranose derivatives are formed, with only partial steric control 123). 

---