Draw the open-chain structure to complete the mutarotation of D-mannose.

• A.
• B.
• C.
• D.

Answer: (B)

Verified step by step guidance

1. Understand that mutarotation involves the interconversion between the alpha and beta anomers of a sugar through an open-chain form.
2. Identify the structure of D-mannose in its cyclic form. The images show both the alpha and beta forms of D-mannose.
3. Recognize that the open-chain form of D-mannose is an aldose, specifically an aldohexose, which means it has an aldehyde group at one end and six carbon atoms.
4. Draw the open-chain structure by starting with the aldehyde group (CHO) at the top, followed by the carbon chain. D-mannose has the following configuration: the second carbon (C2) has the hydroxyl group on the left, the third carbon (C3) has the hydroxyl group on the right, the fourth carbon (C4) has the hydroxyl group on the right, and the fifth carbon (C5) has the hydroxyl group on the right.
5. Ensure that the open-chain form can cyclize to form either the alpha or beta anomer by forming a hemiacetal linkage between the C1 aldehyde and the C5 hydroxyl group, resulting in a six-membered ring.