Textbook Question
Draw the structures of the hemiacetals or hemiketals formed in these reactions:
b.
Ch.15 Aldehydes and Ketones
McMurry8th EditionFundamentals of GOBISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
Chapter 15, Problem 20b
The carbonyl group can be reduced by addition of a hydride ion (H–) and (H+) a proton. Removal of H– and H+ from an alcohol results in a carbonyl group.
b. In the reaction, indicate which direction represents reduction and which represents oxidation.
Verified step by step guidance1
Understand the key concepts: Reduction involves the gain of electrons or hydrogen (H⁻ and H⁺), while oxidation involves the loss of electrons or hydrogen. In organic chemistry, reduction often converts a carbonyl group (C=O) to an alcohol (C-OH), and oxidation does the reverse.
Identify the functional groups involved: A carbonyl group (C=O) is being converted to an alcohol (C-OH) in one direction, and the alcohol is being converted back to a carbonyl group in the opposite direction.
Determine the direction of reduction: The addition of H⁻ (hydride ion) and H⁺ (proton) to the carbonyl group (C=O) results in the formation of an alcohol (C-OH). This process represents reduction because hydrogen is being added.
Determine the direction of oxidation: The removal of H⁻ (hydride ion) and H⁺ (proton) from the alcohol (C-OH) results in the formation of a carbonyl group (C=O). This process represents oxidation because hydrogen is being removed.
Summarize the directions: The conversion of a carbonyl group (C=O) to an alcohol (C-OH) is reduction, while the conversion of an alcohol (C-OH) to a carbonyl group (C=O) is oxidation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reduction and Oxidation
Reduction and oxidation are fundamental chemical processes that involve the transfer of electrons. Reduction refers to the gain of electrons or hydrogen, while oxidation involves the loss of electrons or hydrogen. In organic chemistry, the addition of a hydride ion (H⁻) to a carbonyl group signifies reduction, whereas the removal of H⁻ and H⁺ from an alcohol to form a carbonyl indicates oxidation.
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Reduction of Monosaccharides Example 1
Carbonyl Group
The carbonyl group (C=O) is a functional group characterized by a carbon atom double-bonded to an oxygen atom. It is a key feature in various organic compounds, including aldehydes and ketones. Understanding the reactivity of the carbonyl group is essential for predicting the outcomes of reduction and oxidation reactions, as it can easily undergo transformations with the addition or removal of hydrogen.
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Hydride Ion (H⁻)
A hydride ion (H⁻) is a negatively charged ion formed when a hydrogen atom gains an electron. In reduction reactions, hydride ions act as strong reducing agents, donating electrons to other molecules, such as carbonyl compounds. This process is crucial in organic synthesis, as it allows for the conversion of carbonyl groups into alcohols, demonstrating the practical applications of reduction in chemical reactions.
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Related Practice
Textbook Question
For each compound shown next, determine whether it is a hemiacetal, a hemiketal, an acetal, or a ketal.
a.
b.
c.
d.
Textbook Question
The carbonyl group can be reduced by addition of a hydride ion (H–) and (H+) a proton. Removal of H– and H+ from an alcohol results in a carbonyl group.
a. To which atom of the carbonyl is the hydride ion added and why?
Textbook Question
A fundamental difference between aldehydes and ketones is that one can be oxidized to carboxylic acids but the other cannot. Which is which? Give an example of a test to differentiate aldehydes from ketones.
Textbook Question
Glucose is the major sugar in mammalian blood. We often see it represented as either the "free aldehyde" or the cyclic hemiacetal forms shown here. Of the two forms of glucose, the cyclic hemiacetal is the preferred form found in blood. Can you suggest two reasons why?
Textbook Question
Draw a structure for a compound that meets each of the following descriptions:
a. A 6-carbon cyclic ketone with a methyl group on the beta carbon