Question

What are the differences in the Haworth structures of $\alpha$-D-glucose and $\beta$-D-glucose? (13.4)

Short answer

An Anomer of a saccharide only differs in its structure at the anomeric carbon. Anomeric carbon being the functional group of the carbohydrate, which is usually the carboxyl group attached to it.

Step-by-step solution

Introduction

An anomer is actually anepimer (also a cyclic saccharide) that differs in configuration, particularly at the acetal or hemiacetal carbon (refer to the image below to differentiate between acetal and hemiacetal carbons).

• An anomer is a kind of stereoisomer.
• The anomers are saccharides or glycosides that are epimers, which are distinct from each other in the configuration at C-2.
• If they are ketoses, or in the configuration of C-1, if they are aldoses.

Step 2:  Differences in the Haworth structures of α-D-glucose and β-D-glucose

• There are two forms of d-glucose.
• These different forms, called anomers, differ only by the position of the -OH group at carbon 1.
• In the a $\left(\mathrm{\alpha }\right)$anomer, the $-\mathrm{OH}$group is drawn below the plane of the ring. In the$\left(\mathrm{\beta }\right)$anomer, the $-\mathrm{OH}$group is drawn above the plane of the ring.