Chapter 5, Problem 5.34P

Interpretation Introduction

(a)

Interpretation:

The Fischer projection structure of $\text{L-mannose}$ is to be drawn.

Concept introduction:

Fischer projections are used to represent the configurations about asymmetric carbons in a molecule. Perpendicular intersecting lines represent a carbon atom from the longest carbon chain. The bonds between carbon atoms from this chain are represented by vertical lines. Bonds to the two groups attached to each carbon are represented by horizontal lines. Horizontal bonds point toward the viewer whereas vertical bonds point away from the viewer.

The Fischer projections of the isomers of glyceraldehyde gives, the D/L system of classification of carbohydrates. If the location of the $-\text{OH}$ group on the highest numbered asymmetric carbon matches with that in $\text{D-glyceraldehyde}$ on the right, the carbohydrate is designated D. If it matches with the location of the $-\text{OH}$ group in $\text{L-glyceraldehyde}$ on the left, the carbohydrate is designated L.

D and L sugars are isomers of each other.

Epimers are isomers that differ in configuration at only one asymmetric carbon.

Interpretation Introduction

(b)

Interpretation:

The Fischer projection structure of L-arabinose is to be drawn.

Concept introduction:

Fischer projections are used to represent the configurations about asymmetric carbons in a molecule. Perpendicular intersecting lines represent a carbon atom from the longest carbon chain. The bonds between carbon atoms from this chain are represented by vertical lines. Bonds to the two groups attached to each carbon are represented by horizontal lines. Horizontal bonds point toward the viewer whereas vertical bonds point away from the viewer.

The Fischer projections of the isomers of glyceraldehyde gives, the D/L system of classification of carbohydrates. If the location of the $-\text{OH}$ group on the highest numbered asymmetric carbon matches with that in $\text{D-glyceraldehyde}$ on the right, the carbohydrate is designated D. If it matches with the location of the $-\text{OH}$ group in $\text{L-glyceraldehyde}$ on the left, the carbohydrate is designated L.

D and L sugars are isomers of each other.

Epimers are isomers that differ in configuration at only one asymmetric carbon.

Interpretation Introduction

(c)

Interpretation:

The Fischer projection of $\text{L-threose}$ is to be drawn

Concept introduction:

Fischer projections are used to represent the configurations about asymmetric carbons in a molecule. Perpendicular intersecting lines represent a carbon atom from the longest carbon chain. The bonds between carbon atoms from this chain are represented by vertical lines. Bonds to the two groups attached to each carbon are represented by horizontal lines. Horizontal bonds point toward the viewer whereas vertical bonds point away from the viewer.

The Fischer projections of the isomers of glyceraldehyde gives, the D/L system of classification of carbohydrates. If the location of the $-\text{OH}$ group on the highest numbered asymmetric carbon matches with that in $\text{D-glyceraldehyde}$ on the right, the carbohydrate is designated D. If it matches with the location of the $-\text{OH}$ group in $\text{L-glyceraldehyde}$ on the left, the carbohydrate is designated L.

D and L sugars are isomers of each other.

Epimers are isomers that differ in configuration at only one asymmetric carbon.

Interpretation Introduction

(d)

Interpretation:

The Fischer projection structure of C2 epimer of $\text{L-arabinose}$ is to be drawn.

Concept introduction:

The pair of stereoisomers is nothing but Epimers. Epimers are isomers that shows difference in the configuration at only one chiral centre.