Question

Draw a chair conformation for the \(\alpha\) form of a disaccharide in which two units of D-glucopyranose are joined by a \(\beta-1,3\)-glycosidic bond.

Short answer

Question: Draw a chair conformation for the α-form of a disaccharide in which two units of D-glucopyranose are joined by a β-1,3-glycosidic bond.

Step-by-step solution

Draw a chair conformation for a single unit of D-glucopyranose

To draw a chair conformation for a single unit of D-glucopyranose, we need to represent the six-membered ring as a three-dimensional structure. Label the carbon atoms from C1 to C6. The ring will have the following configuration: - C1 has an axial OH group (up) - C2 has an equatorial OH group (up) - C3 has an equatorial OH group (up) - C4 has an equatorial OH group (down) - C5 has an equatorial OH group (up) - C6 has an axial CH2OH group (up) linked to the fifth carbon (C5)

Draw another chair conformation for the second unit of D-glucopyranose

We will now draw a second chair conformation for the second unit of D-glucopyranose, just as in Step 1. Make sure that both chair conformations have the same orientation.

Join the two units with a β-1,3-glycosidic bond

A β-1,3-glycosidic bond forms between the C1 of one unit and the C3 of the second unit. To represent this bond in the chair conformation, follow these steps: 1. Remove the OH group on the C1 of the first unit and the OH group on the C3 of the second unit. 2. Connect the exposed C1 of the first unit to the exposed C3 of the second unit with a bond. 3. Make sure that the bond is pointing upward, which indicates that it's a β-glycosidic bond. 4. Finally, draw the two connected chair conformations to represent the disaccharide α-form joined by a β-1,3-glycosidic bond. Once you have followed these steps, you will have successfully drawn a chair conformation for the α-form of a disaccharide in which two units of D-glucopyranose are joined by a β-1,3-glycosidic bond.