Chapter 18, Problem 18.91EP

(a)

Interpretation Introduction

Interpretation: The name of the given $\alpha -\text{D}-\text{monosaccharide}$ has to be stated.

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

• Ø For $\alpha$ and $\beta$ configurations, if in the cyclic form of Haworth projection, $\text{OH}$ group is placed below the ring then the same hydroxyl group is drawn at the right position in Fischer projection formula.
• Ø If in the cyclic form of Haworth projection, $\text{OH}$ group is placed above the ring then the same hydroxyl group is drawn at the left position in Fischer projection formula.
• Ø 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 and in the Fischer projection formula it is placed at the left side.

Answer to Problem 18.91EP

The name of the given $\alpha -\text{D}-\text{monosaccharide}$ is $\alpha -\text{D}-\text{glucose}$.

Explanation of Solution

The given Haworth projection formula is shown as,

The open-chain form of the given Haworth projection formula of an $\alpha -\text{D}-\text{monosaccharide}$ is shown as,

Thus, according to the open-chain structure, the name of the given monosaccharide is $\alpha -\text{D}-\text{glucose}$.

(b)

Interpretation Introduction

Interpretation: The name of the given $\alpha -\text{D}-\text{monosaccharide}$ has to be stated.

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

• Ø For $\alpha$ and $\beta$ configurations, if in the cyclic form of Haworth projection, $\text{OH}$ group is placed below the ring then the same hydroxyl group is drawn at the right position in Fischer projection formula.
• Ø If in the cyclic form of Haworth projection, $\text{OH}$ group is placed above the ring then the same hydroxyl group is drawn at the left position in Fischer projection formula.
• Ø 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 and in the Fischer projection formula it is placed at the left side.

Answer to Problem 18.91EP

The name of the given $\alpha -\text{D}-\text{monosaccharide}$ is $\alpha -\text{D}-\text{galactose}$.

Explanation of Solution

The given Haworth projection formula is shown as,

The open-chain form of the given Haworth projection formula of an $\alpha -\text{D}-\text{monosaccharide}$ is shown as,

Thus, according to the open-chain structure, the name of the given monosaccharide is $\alpha -\text{D}-\text{galactose}$.

(c)

Interpretation Introduction

Interpretation: The name of the given $\beta -\text{D}-\text{monosaccharide}$ has to be stated.

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

• Ø For $\alpha$ and $\beta$ configurations, if in the cyclic form of Haworth projection, $\text{OH}$ group is placed below the ring then the same hydroxyl group is drawn at the right position in Fischer projection formula.
• Ø If in the cyclic form of Haworth projection, $\text{OH}$ group is placed above the ring then the same hydroxyl group is drawn at the left position in Fischer projection formula.
• Ø 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 and in the Fischer projection formula it is placed at the left side.

Answer to Problem 18.91EP

The name of the given $\beta -\text{D}-\text{monosaccharide}$ is $\beta -\text{D}-\text{mannose}$.

Explanation of Solution

The given Haworth projection formula is shown as,

The open-chain form of the given Haworth projection formula of a $\beta -\text{D}-\text{monosaccharide}$ is shown as,

Thus, according to the open-chain structure, the name of the given monosaccharide is $\beta -\text{D}-\text{mannose}$.

(d)

Interpretation Introduction

Interpretation: The name of the given $\beta -\text{D}-\text{monosaccharide}$ has to be stated.

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

• Ø For $\alpha$ and $\beta$ configurations, if in the cyclic form of Haworth projection, $\text{OH}$ group is placed below the ring then the same hydroxyl group is drawn at the right position in Fischer projection formula.
• Ø If in the cyclic form of Haworth projection, $\text{OH}$ group is placed above the ring then the same hydroxyl group is drawn at the left position in Fischer projection formula.
• Ø 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 and in the Fischer projection formula it is placed at the left side.

Answer to Problem 18.91EP

The name of the given $\beta -\text{D}-\text{monosaccharide}$ is $\beta -\text{D}-\text{sorbose}$.

Explanation of Solution

The given Haworth projection formula is shown as,

The open-chain form of the given Haworth projection formula of a $\beta -\text{D}-\text{monosaccharide}$ is shown as,

Thus, according to the open-chain structure, the name of the given monosaccharide is $\beta -\text{D}-\text{sorbose}$.