In which configuration is the -OR/OH group located in α sugars?

In α sugars, the -OR/OH group refers to the hydroxyl group or the alkoxy group at the anomeric carbon, which is the carbon derived from the carbonyl carbon of the sugar. The distinction of α from β anomers is based on the orientation of this anomeric hydroxyl group relative to the -CH2OH group, which is typically located at the highest-numbered carbon in the sugar (for aldoses) or at the penultimate carbon in ketoses.

In the case of α sugars, the -OR/OH group is positioned on the opposite side of the -CH2OH group when viewed in the Haworth projection. This means that if the -CH2OH group is pointing up, the -OR/OH group on the anomeric carbon will be pointing down, making them opposite to each other. This configuration is key to distinguishing between the two anomeric forms of sugars and is essential in understanding sugar reactivity and interaction in biochemical pathways.