Q.13.69 - An Introduction to General, Organic, and Biological Chemistry

Question

The sugar D-gulose is a sweet-tasting syrup. (13.3, 13.4)

 

a. Draw the Fischer projection for L-gulose.

b. Draw the Haworth structures for  $\alpha$- and $\beta$-D-gulose.

Step-by-Step Solution

Answer

Part a) An Anomer of a saccharide only differs in its structure at the anomeric carbon.

Part b) Anomeric carbon is the functional group of the carbohydrate, which is usually the carboxyl group attached to it. 

Part c) Epimeres, differ at only one chiral center, not the anomeric carbon.

Step 1: Introduction (Part a)

Aldehydo-L-glucose is the L-enantiomer of aldehydo-glucose. It is a L-glucose and an aldehydo-glucose. It is an enantiomer of an aldehydo-D-glucose.

Step 2: Draw the Fischer projection for L-gulose. (Part a)

$-\mathrm{OH}$ on farthest chiral $\mathrm{C}$ is on left so it is $L-$Glucose

Step 3: b) Draw the Haworth structures for α - and β -D-gulose.

The Haworth structure.