Chapter 24.5, Problem 3LTS

Interpretation Introduction

Interpretation:

The more stable chair conformation of α-D-galactopyranose should be drawn.

Concept introduction:

• Haworth projection is used to represent sugars in their cyclic forms.
• In Haworth projection,
  • α-indicates the –OH group of anomeric carbon C1 and ${\text{CH}}_{\text{2}}\text{OH}$ substituent on the C5 carbon is trans to each other.
  • D indicates the ${\text{CH}}_{\text{2}}\text{OH}$ substituent on the C5 carbon is on up position.
  • The right side and left side –OH groups of chiral carbons in fisher projection are drawn as down side and upward side respectively.
• Chair conformation is drawn according to the respective carbons in Haworth projection.
• Stability of chair conformation is depending upon the positions of bulky substituents whether on axial or equatorial, the location of bulky substituents on equatorial position is more stable than bulky substituents on axial position.