In the cyclic structure of D-fructofuranose, which carbon atom is the anomeric carbon?

Step-by-step solution

D-fructose is a ketohexose with the ketone group located at the C-2 position in its open-chain structure. During the formation of the cyclic D-fructofuranose structure, the hydroxyl group at C-5 undergoes an intramolecular nucleophilic addition to the carbonyl carbon at C-2, forming a hemiketal ring. The carbonyl carbon (C-2) becomes a new chiral center in this cyclic structure. This newly formed chiral center is known as the anomeric carbon. Therefore, the anomeric carbon in D-fructofuranose is C-2. Answer: C-2