Textbook Question
Within each set of structures, indicate which will react fastest, and which slowest, toward nucleophilic addition in basic conditions.
(a)
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Ch. 18 - Ketones and Aldehydes
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 18, Problem 65d,e,f
Which of the following compounds would give a positive Tollens test? (Remember that the Tollens test involves mild basic aqueous conditions.)
(d) CH3CH2CH2CH2CH(OH)OCH3
(e) CH3CH2CH2CH2CH(OCH3)2
(f) 
Verified step by step guidance1
Step 1: Recall the purpose of the Tollens test. The Tollens test is used to identify aldehydes. It involves the oxidation of aldehydes to carboxylic acids using a silver-ammonia complex, which results in the formation of a silver mirror. Ketones, alcohols, and ethers do not give a positive Tollens test.
Step 2: Analyze the structure of compound (d) CH3CH2CH2CH2CH(OH)OCH3. This compound contains an ether group (-OCH3) and a secondary alcohol (-CH(OH)-). Neither of these functional groups is an aldehyde, so this compound will not give a positive Tollens test.
Step 3: Analyze the structure of compound (e) CH3CH2CH2CH2CH(OCH3)2. This compound contains two ether groups (-OCH3) attached to the same carbon atom. Again, there is no aldehyde group present, so this compound will not give a positive Tollens test.
Step 4: Analyze the structure of compound (f), shown in the image. The compound is a cyclic structure with a carbonyl group (C=O) and a hydroxyl group (-OH) attached to the same carbon atom. This is a hemiacetal, not an aldehyde. Hemiacetals do not give a positive Tollens test.
Step 5: Conclude that none of the given compounds (d, e, or f) will give a positive Tollens test, as none of them contain an aldehyde functional group.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Tollens Test
The Tollens test is a qualitative test used to identify aldehydes and certain alpha-hydroxy ketones. It involves the use of Tollens' reagent, which contains silver nitrate in ammonia, and reacts with compounds that can be oxidized to form carboxylic acids. A positive result is indicated by the formation of a silver mirror on the test tube's surface, signifying the reduction of silver ions.
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Aldehydes vs. Ketones
Aldehydes are organic compounds characterized by the presence of a carbonyl group (C=O) at the end of a carbon chain, making them more reactive than ketones, which have the carbonyl group located within the chain. Only aldehydes can typically give a positive Tollens test, as they can be oxidized to carboxylic acids, while ketones generally do not react under these conditions.
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Functional Groups
Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In the context of the Tollens test, the presence of an aldehyde functional group (-CHO) is crucial for a positive result, while other groups, such as alcohols or ethers, do not participate in the reaction, highlighting the importance of identifying functional groups in organic compounds.
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Related Practice
Textbook Question
Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound.
d. cyclodecyne
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Textbook Question
Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound.
e. 3-methylcyclodecyne
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Textbook Question
Which of the following compounds would give a positive Tollens test? (Remember that the Tollens test involves mild basic aqueous conditions.)
(a) CH3CH2CH2COCH3
(b) CH3CH2CH2CH2CHO
(c) CH3CH=CHCH=CHOH
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Textbook Question
Solving the following road-map problem depends on determining the structure of A, the key intermediate. Give structures for compounds A through K.
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Textbook Question
Within each set of structures, indicate which will react fastest, and which slowest, toward nucleophilic addition in basic conditions.
(b)
601
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