Chapter 18, Problem 18.79EP

(a)

Interpretation Introduction

Interpretation: The Haworth projection formula for the $\alpha -\text{anomer}$ of the given Fischer projection formula of a monosaccharide has to be drawn.

Concept introduction: The Haworth projection formula can be drawn by using the following rules.

• • For $\alpha$ and $\beta$ configurations, if hydroxyl group is drawn at the right position in Fischer projection formula then in the cyclic form of Haworth projection, the same $\text{OH}$ group should be drawn below the ring.
• • If hydroxyl group is drawn at the left position in Fischer projection formula then in the cyclic form of Haworth projection, the same $\text{OH}$ group should be drawn above the ring.
• • For $\beta$ configuration, the position of $\text{OH}$ group at the first carbon with respect to ${\text{CH}}_{\text{2}}\text{OH}$ group always remains in the same direction.
• • For $\alpha$ configuration, the position of $\text{OH}$ group at the first carbon with respect to ${\text{CH}}_{\text{2}}\text{OH}$ group always remains in the opposite direction.
• • The hydroxyl group that is obtained from the carbonyl group can be placed above or below the ring which is dependent upon the ring closure of the cyclic form.
• • For D configuration, ${\text{CH}}_{\text{2}}\text{OH}$ group always placed above the cyclic ring.
• • For L configuration, ${\text{CH}}_{\text{2}}\text{OH}$ group always placed below the cyclic ring.

(b)

Interpretation Introduction

Interpretation: The Haworth projection formula for the $\alpha -\text{anomer}$ of the given Fischer projection formula of a monosaccharide has to be drawn.

Concept introduction: The Haworth projection formula can be drawn by using the following rules.

• • For $\alpha$ and $\beta$ configurations, if hydroxyl group is drawn at the right position in Fischer projection formula then in the cyclic form of Haworth projection, the same $\text{OH}$ group should be drawn below the ring.
• • If hydroxyl group is drawn at the left position in Fischer projection formula then in the cyclic form of Haworth projection, the same $\text{OH}$ group should be drawn above the ring.
• • For $\beta$ configuration, the position of $\text{OH}$ group at the first carbon with respect to ${\text{CH}}_{\text{2}}\text{OH}$ group always remains in the same direction.
• • For $\alpha$ configuration, the position of $\text{OH}$ group at the first carbon with respect to ${\text{CH}}_{\text{2}}\text{OH}$ group always remains in the opposite direction.
• • The hydroxyl group that is obtained from the carbonyl group can be placed above or below the ring which is dependent upon the ring closure of the cyclic form.
• • For D configuration, ${\text{CH}}_{\text{2}}\text{OH}$ group always placed above the cyclic ring.
• • For L configuration, ${\text{CH}}_{\text{2}}\text{OH}$ group always placed below the cyclic ring.