Planar representation to chair conformation

[leopard]

For carbohydrates, the $$\alpha$$ position is to the right in a Fischer projection and down in a planar representation. Is it axial or equatorial in a chair conformation?

My book also says that all the OH groups in $$\beta$$-D-glucose are in axial positions. Is this true?

 

[chemisttree]

For carbohydrates, the $$\alpha$$ position is to the right in a Fischer projection and down in a planar representation. Is it axial or equatorial in a chair conformation?

My book also says that all the OH groups in $$\beta$$-D-glucose are in axial positions. Is this true?

You will note that in $$\beta$$-D-glucose the OH groups alternate left and right. This is the perfect alignment to have all of the OH groups in an equatorial arrangement. It is also the perfect alignment to have all of the OH groups (and the CH2OH group) in an axial arrangement. Which arrangement would be of lowest energy?

 

[Blueshift5]

In a chair conformation, the alpha position of a carbohydrate is considered to be in the equatorial position. This is because the equatorial position is more stable and allows for better interaction with neighboring groups. In contrast, the axial position is less stable and can lead to steric hindrance. Therefore, in a chair conformation, the alpha position is typically found in the equatorial position.

Regarding the statement about all OH groups in beta-D-glucose being in axial positions, this is not entirely accurate. In a beta-D-glucose molecule, the OH groups at the C2, C3, and C5 positions are in axial positions, while the OH group at the C4 position is in an equatorial position. This is due to the fact that in a beta-D-glucose molecule, the OH group at the C4 position is pointing down in a planar representation, while the other OH groups are pointing up. It is important to note that the positions of these OH groups can vary depending on the specific conformation of the molecule.