Chapter 24.5, Problem 15ATS

Interpretation Introduction

Interpretation:

The two pyranose forms of D-talose formed when it is dissolved in water should be drawn.

Concept introduction:

• The –OH group of compound attacks the carbonyl group of the same compound, thereby a ring is formed by the carbon atoms and oxygen atom of –OH group with incorporating into the ring.
• 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.
• Mutarotation is the change of specific rotation of an anomer when dissolved in water. It is due to the equilibrium formation of two anomeric forms and open chain form.