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Ch.13 Carbohydrates
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
All textbooksTimberlake 13th EditionCh.13 CarbohydratesProblem 39
Chapter 13, Problem 39

Draw the Fischer projection for the oxidation and the reduction products of D-arabinose. What are the names of the sugar acid and the sugar alcohol produced?

Verified step by step guidance
1
Understand the problem: D-arabinose is a monosaccharide (a simple sugar) with an aldehyde functional group. Oxidation of the aldehyde group will produce a sugar acid, while reduction of the aldehyde group will produce a sugar alcohol. Fischer projections are used to represent the stereochemistry of these molecules.
Step 1: Oxidation of D-arabinose. In this reaction, the aldehyde group (-CHO) at the top of the Fischer projection is oxidized to a carboxylic acid group (-COOH). The stereochemistry of the remaining chiral carbons remains unchanged. Draw the Fischer projection of the resulting sugar acid, ensuring the -COOH group is at the top.
Step 2: Reduction of D-arabinose. In this reaction, the aldehyde group (-CHO) at the top of the Fischer projection is reduced to a primary alcohol group (-CH2OH). Again, the stereochemistry of the remaining chiral carbons remains unchanged. Draw the Fischer projection of the resulting sugar alcohol, ensuring the -CH2OH group is at the top.
Step 3: Name the sugar acid. The sugar acid formed from the oxidation of D-arabinose is named by replacing the '-ose' suffix of the sugar with '-onic acid.' For D-arabinose, the sugar acid is called D-arabinonic acid.
Step 4: Name the sugar alcohol. The sugar alcohol formed from the reduction of D-arabinose is named by replacing the '-ose' suffix of the sugar with '-itol.' For D-arabinose, the sugar alcohol is called D-arabinitol.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Fischer Projection

The Fischer projection is a two-dimensional representation of a three-dimensional organic molecule, particularly useful for depicting the stereochemistry of carbohydrates. In this format, the carbon chain is arranged vertically, with the most oxidized carbon at the top. Horizontal lines represent bonds that project out of the plane towards the viewer, while vertical lines represent bonds that extend behind the plane.
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Fischer Projections Example 1

Oxidation and Reduction in Carbohydrates

Oxidation and reduction are chemical reactions that involve the transfer of electrons. In carbohydrates, oxidation typically involves the conversion of an alcohol group (-OH) to a carbonyl group (C=O), resulting in the formation of sugar acids. Conversely, reduction involves the addition of electrons, often converting carbonyl groups back to alcohols, leading to the formation of sugar alcohols.
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Reduction of Monosaccharides Example 1

Sugar Acids and Sugar Alcohols

Sugar acids are derived from sugars through oxidation, resulting in the formation of carboxylic acid groups. For example, D-arabinose can be oxidized to produce D-arabinonic acid. Sugar alcohols, on the other hand, are produced through the reduction of sugars, where the carbonyl group is reduced to an alcohol group, such as D-arabinitol from D-arabinose.
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Common Naming of Sugar Alcohols Concept 3
Related Practice
Textbook Question

Identify each of the following as the α or ß isomer:

a.

Textbook Question

Draw the Fischer projection for the oxidation and the reduction products of D-xylose. What are the names of the sugar acid and the sugar alcohol produced?

Textbook Question

Identify the disaccharide that fits each of the following descriptions: 

a. ordinary table sugar

Textbook Question

Draw the Fischer projection for the oxidation and the reduction products of D-mannose. What are the names of the sugar acid and the sugar alcohol produced?

Textbook Question

Indicate whether each disaccharide in Problem 13.41 is a reducing sugar or not.

a.

b.

Textbook Question

For each of the following, give the monosaccharide units produced by hydrolysis, the type of glycosidic bond, and the name of the disaccharide, including α or β:

a.