Question

Define the following term: Anomers.

Hint:

Anomers are two cyclic forms of a sugar that differ only in the arrangement of the -OH group at the new chiral carbon formed when the sugar closes into a ring. This carbon is called the anomeric carbon (C-1 in glucose).

Answer 1

Step 1: Recall ring formation.
When an open-chain sugar like glucose closes into a ring, a new chiral carbon is created at carbon-1. This carbon is called the anomeric carbon.

Step 2: Look at the new \(-OH\) group.
At this anomeric carbon, the \(-OH\) group can point in two different directions, giving two different ring forms.

Step 3: Define anomers.
Anomers are two cyclic forms of a sugar that differ only in the position of the \(-OH\) group at the anomeric carbon.

Step 4: Give the example.
In glucose, alpha-D-glucose has the \(-OH\) at C-1 pointing down, while beta-D-glucose has it pointing up.

Step 5: Note the relationship.
They are diastereomers of each other and can change into one another in solution (mutarotation).

Answer: Anomers are a pair of cyclic sugar forms that differ only in the configuration of the \(-OH\) at the anomeric carbon, for example alpha-D-glucose and beta-D-glucose.