Intro to Stereochem and Carbs

Question 0

Stereoisomers

Answer 0

• Differ only in the way the atoms are oriented in space (Configuration).
• Have identical IUPAC names (except for a prefix like cis or trans).
• Always have the same functional group(s).
• Can be Geometric (cis/trans) or Optical (chiral & exhibit optical activity)

Question 1

Constitutional/structural isomers

Answer 1

• Have different IUPAC names
• The same or different functional groups
• Different physical chemical properties.

Question 2

Enantiomers

Answer 2

Stereoisomers whose molecules are non-superimposable mirror images of each other

Question 3

Properties of enantiomers

Answer 3

• Identical MP and BP
• Identical solubility
• Identical refraction index and spectra
• Interact and react with other chiral molecules at different rate
• Rotate plane polarized light equally but in different direction

Question 4

Racemate

Answer 4

Equal amount of two enantiomers. Optically inactive

Question 5

Diastereomers

Answer 5

Stereoisomers that are not mirror images of each other

• Have different physical and chemical properties
• For a molecule with n stereogenic centers, the maximum number of stereoisomers is 2n.

Question 6

Enantiomeric excess (ee)

Answer 6

A measurement of the excess of one enantiomer over the racemic mixture. High ee means High optical purity. Required by FDA in order for drug to be marketed

ee = % of one enantiomer - % of the other enantiomer.

Question 7

Mutarotation

Answer 7

Interconversion of anomeric forms

Question 8

Reducing Sugar

Answer 8

Any sugar that forms some aldehyde or ketone. Allows sugar to act as a reducing agent.

• must have a free hydroxyl group on the anomeric carbon atom