91Ó°ÊÓ

Ephedrine and pseudoephedrine are connected to each other in terms of structure. These molecules are employed to cure nasal congestion.

a. The groups connected to the stereogenic center have to be prioritized to recognize the stereochemistry of a particular compound. The groups possessing greater atomic numbers have greater preference than the ones with lower atomic numbers.

The compound is given the configuration R if the rotation is in the clockwise direction. The configuration will be S if the rotation is in the anticlockwise direction.

The structure of (–)-ephedrine possessing 1R, 2Sconfiguration is given below.

Structure of (–)-ephedrine

b. The structure of (+)-pseudoephedrine possessing 1S, 2S configuration is given below.

Structure of (+)-pseudoephedrine

c. The structures of ephedrine and pseudoephedrine are shown below

Structures of ephedrine and pseudoephedrine

One stereogenic center has the same configuration in both the compounds, and the other stereogenic center has an opposite configuration. Hence these compounds are regarded as diastereomers.

d. The other stereoisomers of (–)-ephedrine and (+)-pseudoephedrine is given below:

Stereoisomers of (–)-ephedrine and (+)-pseudoephedrine

One stereocenter of both the compounds possesses the same configuration, whereas the other stereocenter has a different configuration.

e. Let us consider the comparison of (+)-ephedrine with (-)-ephedrine

Comparison of (+)-ephedrine with (-)-ephedrine

The compounds (+)-ephedrine and (-)-ephedrine are related to each other as enantiomers.

Let us consider the comparison of (-)-pseudoephedrine with (-)-ephedrine

Comparison of (-)-pseudoephedrine with (-)-ephedrine

The compounds(-)-pseudoephedrine and (-)-ephedrine are related to each other as diastereomers.