pyranózových

Pyranózových refers to a class of cyclic hemiacetals or hemiketals derived from pyran, a six-membered heterocyclic ring containing one oxygen atom. In carbohydrate chemistry, pyranózových structures are particularly significant as they represent the most common and stable ring forms of monosaccharides containing six carbon atoms, such as glucose, fructose, and galactose.

These cyclic forms arise from the intramolecular reaction between the carbonyl group (aldehyde or ketone) of a monosaccharide and a hydroxyl group located on a carbon atom further down the chain. When a six-carbon monosaccharide cyclizes to form a pyranose ring, it creates a six-membered ring structure that resembles pyran. The carbons of the monosaccharide are numbered sequentially, and the ring typically involves the hydroxyl group on carbon 5 reacting with the aldehyde or ketone group.

The formation of the pyranose ring introduces a new chiral center at the anomeric carbon, which is the former carbonyl carbon. This leads to the existence of two stereoisomers, known as anomers, designated alpha (α) and beta (β). The orientation of the hydroxyl group on the anomeric carbon determines whether it is an α-anomer or a β-anomer. In aqueous solutions, monosaccharides exist in equilibrium between their open-chain form and their cyclic hemiacetal or hemiketal forms, with the pyranose forms usually predominating due to their thermodynamic stability.