Chapter 6, Problem 6.31AP

Interpretation Introduction

(a)

Interpretation:

The line-and-wedge structures of two stereoisomers, ephedrine and pseudoephedrine in which the asymmetric carbons lie in the plane are to be drawn.

Concept introduction:

The naming of the chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chiral center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other. The line-and-wedge representation is used to show the molecule in three dimensions.

Interpretation Introduction

(b)

Interpretation:

The sawhorse projection and a Newman projection about the $\text{C1}-\text{C2}$ bond for ephedrine and pseudoephedrine are to be drawn.

Concept introduction:

Newman projection is a way of representing the groups attached to carbon atoms in the $\text{C-C}$ bonds. This is used to determine the interaction between the groups attached to carbon atoms and the dihedral angle. The front carbon atom in the Newman projection is represented by the dot and the end carbon atom is represented by the circle. The groups attached to the carbon atoms are then drawn by the line.

The sawhorse representation is used to show the above carbon atom on the right side in a molecule.

Interpretation Introduction

(c)

Interpretation:

The relationship between ephedrine and pseudoephedrine is to be stated. The explanation for the corresponding answer is to be stated.

Concept introduction:

Those compounds which have the same molecular formula but have different arrangements of atoms are known as isomers. The phenomenon is known as isomerism. The isomers are generally classified as structural isomers and stereoisomers. Stereoisomers are further divided into two categories diastereomers and enantiomers.

Interpretation Introduction

(d)

Interpretation:

Whether the melting point of ephedrine and pseudoephedrine should be the same or different is to be stated.

Concept introduction:

Those compounds which have the same molecular formula but have different arrangements of atoms are known as isomers. The phenomenon is known as isomerism. The isomers are generally classified as structural isomers and stereoisomers. Stereoisomers are further divided into two categories diastereomers and enantiomers.

Interpretation Introduction

(e)

Interpretation:

The optical activity of ephedrine and pseudoephedrine is to be predicted.

Concept introduction:

A carbon atom that has four nonequivalent atoms or groups attached to it is known as the chiral carbon atom. Chiral carbon centers are also known as asymmetric or stereogenic centers. A chiral molecule is an optically active molecule. It rotates a plane of the plane-polarized light.