Draw the Haworth projection for the cyclic structure of D-mannose by laying down the Fischer projection.

Verified step by step guidance

1. Start by drawing the Fischer projection of D-mannose. D-mannose is an aldohexose, so it has six carbon atoms. The aldehyde group is at the top, and the hydroxyl groups are arranged as follows: right, left, left, right.
2. Identify the carbon atoms that will form the ring. For D-mannose, the ring is typically formed between the C-1 (aldehyde carbon) and C-5 hydroxyl group, creating a six-membered pyranose ring.
3. Convert the Fischer projection to a Haworth projection. To do this, rotate the Fischer projection 90 degrees clockwise. The right-side hydroxyl groups in the Fischer projection will point down in the Haworth projection, and the left-side groups will point up.
4. Draw the ring structure. Place the oxygen atom in the upper right corner of the hexagon. Number the carbon atoms clockwise starting from the anomeric carbon (C-1) to C-5, with C-6 as a CH2OH group above the ring.
5. Add the hydroxyl groups to the ring. For D-mannose, the hydroxyl groups on C-2 and C-3 will point up, while the hydroxyl groups on C-4 and C-5 will point down. The CH2OH group on C-5 will point up, indicating the D-configuration.

Key Concepts

Fischer Projection

The Fischer projection is a two-dimensional representation of a molecule, particularly useful for depicting the stereochemistry of carbohydrates. In this format, the vertical lines represent bonds that are oriented away from the viewer, while horizontal lines indicate bonds that are coming towards the viewer. This method allows for easy identification of the configuration of chiral centers in sugars, which is essential for converting to cyclic forms.

Haworth Projection

The Haworth projection is a way to represent the cyclic form of carbohydrates, showing the ring structure and the orientation of substituents. It provides a more realistic depiction of the three-dimensional shape of the molecule compared to Fischer projections. In this format, the ring is typically drawn as a planar structure, with substituents positioned above or below the plane, reflecting their actual spatial arrangement in solution.

Cyclic Structure of Carbohydrates

Carbohydrates, such as D-mannose, can exist in both linear and cyclic forms. The cyclic structure arises from the reaction between a carbonyl group and a hydroxyl group within the same molecule, leading to the formation of a hemiacetal. This process is crucial for understanding the stability and reactivity of sugars, as the cyclic form is often more prevalent in biological systems and influences the molecule's properties and interactions.