Question

Question: Draw two possible epimers of D-erythrose. Name each of these compounds using Figure 28.4.

Short answer

Answer

D-threose

L-threose

Step-by-step solution

Epimers

For carbohydrates containing more than one chiral center, some stereoisomers are not mirror images; they are called diastereoisomers.

The diastereoisomers that have different configurations at only one chiral center of the carbohydrate are called epimers.

The physical and chemical properties of epimers are different from each other.

D-erythrose

D-erythrose is a tetrose saccharide. It is a part of the aldose family due to the presence of one aldehyde group.

The chemical formula for erythrose is and was first isolated from rhubarb.

The IUPAC name of D-erythrose is (2R,3R)-2,3,4-trihydroxybutanal and has two chiral centers.

Epimers of D-erythrose

D-erythrose has 2 chiral centers. The structure of D-erythrose can be given as:

D-erythrose

The epimers of D-erythrose can be obtained by changing the configuration around one stereogenic center.

Since the D-erythrose has two stereogenic centers, two epimers can be drawn by changing the configuration at C-2 and C-3. They are D-threose and L-threose, respectively

D-threose

L-threose