Chapter 4.2

Question 1

What are the most stable cyclic sugar molecules in a solution. Note one is six membered and the other is five membered

Answer 1

Six-membered
->pyranose rings

Five-membered
->furanose rings

Question 2

What is the difference between an alpha anomore and a Beta anomer

Answer 2

alpha anomer
->the -OH group of carbon 1 is trans to the CH2OH group

beta anomer
->the -OH group of carbon 1 is cis to the CH2OH group

Question 3

What shape do haworth projections assume for a pyranose ring

Answer 3

• it adopts a chair-like configuration

- >the substituents assume an axial or equatorial position to minimize steric hindrance

Question 4

Describe the process of mutarotation

Answer 4

• expose hemiacetal rings to water
• > will cause them to spontaneously cycle between the open and closed form
• > either the alpha or beta anomer can be formed
• > spontaneous rotation around C-1 is known as mutarotation

Question 5

What does mutarotation result in

Answer 5

• it results in a mixture that contains both alpha and beta anomers at equilibrium concentrations
• alpha concentrations are less favoured
• > because it has a hydroxyl group at the axial end and this results in steric hindrance