Chapter 7: Carbohydrates

Question 1

how do you find the number of possible isomers?

Answer 1

2^n
- n= number of chiral carbons
L> two H = not chiral

Question 2

Enantiomers?

Answer 2

• mirror images

Question 3

diastereomers?

Answer 3

• not mirror images

Question 4

D vs L sugar?

Answer 4

• looking at chiral carbon furthest from the carbonyl group!
• D= right OH
• L= left OH

Question 5

epimers?

Answer 5

• diastereomers that differ via one chiral atom

Question 6

Mutarotation?

Answer 6

• when alpha and beta monosaccharides dissolve in water they interconvert forming an equilibrium mixture of open chain alpha and beta pyranose and furanose forms.
• beta= OH above carbon 1 , alpha= below

Question 7

Steps to drawing a Haworth structure from fischer projection?

Answer 7

1. draw the five or six membered ring
2. number the carbons in both structures
3. draw atoms attached to the anomeric carbon (first carbon n aldoses, second in ketoses)…alpha= down, beta is up
4. the last carbon is always up in D-sugars
5. imagine the fischer projection falling over to the right…the Oh groups that were on the left are now up in the haworth structure…
   L> remember that the carbon furthest via cDoubleBondO reacts to form the oxygen within the ring and been an OH and the anomeric OH had been the carbonyl oxygen.