Chapter 4, Problem 4.25P

Interpretation Introduction

(a)

Interpretation:

The Lewis structure for an aldetetrose is to be drawn.

Concept introduction:

Monosaccharides are called simple sugars, with the number of oxygen atoms same as the number of carbon atoms. The general formula for monosaccharides is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Monosaccharides are cyclic as well as non-cyclic. In mono-saccharides, if the carbonyl group involves a terminal carbon, then it is an aldose. In mono-saccharides, if the carbonyl group involves an internal carbon, then it is a ketose. Sugars are further distinguished on the basis of their carbon atoms. A tetrose sugar contains four, a pentose contains five, and a hexose contains six carbon atoms respectively.

Answer to Problem 4.25P

The Lewis structure for an aldetetrose is

Explanation of Solution

Aldotetrose is a mono-saccharide. The name “aldo” indicates that the carbonyl group must be present at the terminal carbon atom, while the word “tetrose” indicates a chain of four carbon atoms. Thus, aldotetrose is a sugar having an aldehyde group at the terminal carbon atom, and the structure must have four carbon atoms. The general formula for mono-saccharides is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Thus, the molecular formula for the aldotetrose must be ${\text{C}}_4{\text{H}}_8{\text{O}}_4$. The structure for aldotetrose is as below:

The molecular formula for the above structure is ${\text{C}}_4{\text{H}}_8{\text{O}}_4$. Usually, lone pairs of electrons on the atoms, wherever applicable, are shown in the Lewis structure, but in these molecules, it is not relevant, thus ignored.

Conclusion

Altetrose is a mono-saccharide having a carbonyl group at the terminal carbon atom, and its molecular formula is ${\text{C}}_4{\text{H}}_8{\text{O}}_4$.

Interpretation Introduction

(b)

Interpretation:

The Lewis structure for a ketotetrose is to be drawn.

Concept introduction:

Monosaccharides are called simple sugars, with the number of oxygen atoms same as the number of carbon atoms. The general formula for a monosaccharide is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Monosaccharides are cyclic as well as non-cyclic. In mono-saccharides, if the carbonyl group involves a terminal carbon, then it is an aldose. In mono-saccharides, if the carbonyl group involves an internal carbon, then it is a ketose. Sugars are further distinguished on the basis of their carbon atoms. A tetrose sugar contains four, a pentose contains five, and a hexose contains six carbon atoms respectively.

Answer to Problem 4.25P

The Lewis structure for a ketotetrose is

Explanation of Solution

Ketotetrose is a type of mono-saccharide. The name “keto” indicates that the carbonyl group must be present at the internal carbon atom, while the word “tetrose” indicates the chain of four carbon atoms. Thus, ketotetrose is a sugar having a carbonyl group at the internal carbon atom, and the structure must have four carbon atoms. The general molecular formula for mono-saccharides is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Thus, the molecular formula for the ketotetrose must be ${\text{C}}_4{\text{H}}_8{\text{O}}_4$. The structure for ketotetrose is as below:

The molecular formula for the above structure is ${\text{C}}_4{\text{H}}_8{\text{O}}_4$. Usually, lone pairs of electrons on the atoms, wherever applicable, are shown in the Lewis structure, but in these molecules, it is not relevant, thus ignored.

Conclusion

Ketotetrose is a mono-saccharide having a carbonyl group at the internal carbon atom, and its molecular formula is ${\text{C}}_4{\text{H}}_8{\text{O}}_4$.

Interpretation Introduction

(c)

Interpretation:

The Lewis structure for an aldetriose is to be drawn.

Concept introduction:

Monosaccharides are called simple sugars, with the number of oxygen atoms same as the number of carbon atoms. Thus, the general molecular formula for a monosaccharide is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Monosaccharides are cyclic as well as non-cyclic. In mono-saccharides, if the carbonyl group involves a terminal carbon, then it is an aldose. In mono-saccharides, if the carbonyl group involves an internal carbon, then it is a ketose. Sugars are further distinguished on the basis of their carbon atoms. A tetrose sugar contains four, a pentose contains five, and a hexose contains six carbon atoms respectively.

Answer to Problem 4.25P

The Lewis structure for an aldetriose is

Explanation of Solution

Aldotriose is a type of mono-saccharide. The name “aldo”’ indicates that the carbonyl group must be present at the terminal carbon atom, while the word “triose” indicates a chain of three carbon atoms. Thus, aldotriose is a sugar having an aldehyde group at the terminal carbon atom, and the structure must have three carbon chain. The general molecular formula for mono-saccharides is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Thus, the molecular formula for the aldotriose must be ${\text{C}}_3{\text{H}}_6{\text{O}}_3$. The Lewis structure for aldotriose is as below:

The molecular formula for the above structure is ${\text{C}}_3{\text{H}}_6{\text{O}}_3$. Usually, lone pairs of electrons on the atoms, wherever applicable, are shown in the Lewis structure, but in these molecules, it is not relevant, thus ignored.

Conclusion

Altetrose is a mono-saccharide having a carbonyl group at the terminal carbon atom, and its molecular formula is ${\text{C}}_3{\text{H}}_6{\text{O}}_3$.

Interpretation Introduction

(d)

Interpretation:

The Lewis structure for a ketotriose is to be drawn.

Concept introduction:

Monosaccharides are called simple sugars, with the number of oxygen atoms same as the number of carbon atoms. Thus, the general molecular formula for a monosaccharide is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Monosaccharides are cyclic as well as non-cyclic. In mono-saccharides, if the carbonyl group involves a terminal carbon, then it is an aldose. In mono-saccharides, if the carbonyl group involves an internal carbon, then it is a ketose. Sugars are further distinguished on the basis of their carbon atoms. A tetrose sugar contains four, a pentose contains five, and a hexose contains six carbon atoms respectively.

Answer to Problem 4.25P

The Lewis structure for a ketotriose is

Explanation of Solution

Ketotriose is a type of mono-saccharide. The name “keto” indicates that the carbonyl group must be present at the internal carbon atom, while the word “tetrose” indicates the chain of four carbon atoms. Thus, ketotriose is a sugar having a carbonyl group at the internal carbon atom, and the structure must have three carbon atoms. The general molecular formula for mono-saccharides is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Thus, the molecular formula for the ketotetrose must be ${\text{C}}_3{\text{H}}_6{\text{O}}_3$. The Lewis structure for ketotriose is as below:

The molecular formula for the above structure is ${\text{C}}_3{\text{H}}_6{\text{O}}_3$. Usually, lone pairs of electrons on the atoms, wherever applicable, are shown in the Lewis structure, but in these molecules, it is not relevant, thus ignored.

Conclusion

Ketotetrose is a mono-saccharide having a carbonyl group at the internal carbon atom, and its molecular formula is ${\text{C}}_3{\text{H}}_6{\text{O}}_3$.

Interpretation Introduction

(e)

Interpretation:

The Lewis structure for a ketohexose, which is different from fructose, is to be drawn.

Concept introduction:

Monosaccharides are called simple sugars, with the number of oxygen atoms same as the number of carbon atoms. Thus, the general molecular formula for a monosaccharide is ${\text{C}}_{\text{x}}{\text{H}}_{\text{2x}}{\text{O}}_{\text{x}}$. Monosaccharides are cyclic as well as non-cyclic. In mono-saccharides, if the carbonyl group involves a terminal carbon, then it is an aldose. In mono-saccharides, if the carbonyl group involves an internal carbon, then it is a ketose. Sugars are further distinguished on the basis of their carbon atoms. A tetrose sugar contains four, a pentose contains five, and a hexose contains six carbon atoms respectively.

Answer to Problem 4.25P

The Lewis structure for a ketohexose, which is different from fructose, is

Explanation of Solution

The Lewis structure for fructose is

Fructose is a ketohexose with a molecular formula ${\text{C}}_6{\text{H}}_{12}{\text{O}}_6$. In the structure above, note that the position of the carbonyl carbon is at one of the internal carbon atoms in the six carbon chain. Another ketohexose, other than fructose, can be drawn by changing the connectivity of any one of the hydroxyl groups attached. Thus, the Lewis structure for a ketohexose, which is different from fructose is

The molecular formula for the above structure is ${\text{C}}_6{\text{H}}_{12}{\text{O}}_6$. Usually, lone pairs of electrons on the atoms, wherever applicable are shown in the Lewis structure, but in these molecules, it is not relevant, thus ignored.

Conclusion

Ketohexose is a mono-saccharide having a carbonyl group at the internal carbon atom, and its molecular formula is ${\text{C}}_6{\text{H}}_{12}{\text{O}}_6$.