Textbook Question
Each of the following heterocycles includes one or more nitrogen atoms. Classify each nitrogen atom as strongly basic or weakly basic, according to the availability of its lone pair of electrons.
(d)
(e)
1420
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Ch. 16 - Aromatic Compounds
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 16, Problem 35(1)a,b,c
Some of the following compounds show aromatic properties, and others do not.
1. Predict which ones are likely to be aromatic, and explain why they are aromatic.
(a) 
(b) 
(c) 
Verified step by step guidance1
Step 1: Recall the criteria for aromaticity. A compound is aromatic if it satisfies the following conditions: (a) It is cyclic, (b) It is planar, (c) It has a conjugated π-electron system, and (d) It follows Huckel's rule, which states that the molecule must have (4n + 2) π-electrons, where n is a non-negative integer.
Step 2: Analyze compound (i). The structure is a six-membered ring with alternating double bonds (a conjugated π-electron system). The positive charge on the oxygen atom contributes to the delocalization of electrons, making the system planar and cyclic. Count the π-electrons to check if it satisfies Huckel's rule.
Step 3: Analyze compound (ii). The structure is a six-membered ring with alternating double bonds and a ketone group. The conjugated π-electron system is present, and the molecule appears cyclic and planar. Count the π-electrons to determine if it satisfies Huckel's rule.
Step 4: Analyze compound (iii). The structure is a six-membered ring with alternating double bonds and a ketone group. The conjugated π-electron system is present, and the molecule appears cyclic and planar. Count the π-electrons to determine if it satisfies Huckel's rule.
Step 5: Compare the π-electron counts for each compound to Huckel's rule (4n + 2). Determine which compounds satisfy all the criteria for aromaticity and explain why they are aromatic or not based on the analysis.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Aromaticity
Aromaticity refers to a property of cyclic compounds that exhibit enhanced stability due to the delocalization of π electrons across the ring structure. For a compound to be aromatic, it must be cyclic, planar, and follow Hückel's rule, which states that it should have (4n + 2) π electrons, where n is a non-negative integer.
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Intro to Aromaticity
Hückel's Rule
Hückel's rule is a criterion used to determine the aromaticity of a compound. It states that a planar, cyclic molecule is aromatic if it contains a total of (4n + 2) π electrons in its conjugated system. This rule helps predict the stability and reactivity of aromatic compounds compared to non-aromatic or anti-aromatic compounds.
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Conjugation
Conjugation occurs when p-orbitals overlap across adjacent bonds, allowing for the delocalization of π electrons. This delocalization contributes to the stability of aromatic compounds. In the context of the question, identifying conjugated systems within the given structures is essential for determining their aromatic properties.
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Related Practice
Textbook Question
Some of the following compounds show aromatic properties, and others do not.
1. Predict which ones are likely to be aromatic, and explain why they are aromatic.
2. Predict which nitrogen atoms are more basic than water and which are less basic.
(d)
675
views
Textbook Question
The following molecules and ions are grouped by similar structures. Classify each as aromatic, antiaromatic, or nonaromatic. For the aromatic and antiaromatic species, give the number of pi electrons in the ring.
(g)
522
views
Textbook Question
Some of the following compounds show aromatic properties, and others do not.
1. Predict which ones are likely to be aromatic, and explain why they are aromatic.
2. Predict which nitrogen atoms are more basic than water and which are less basic.
(e)
484
views
Textbook Question
Each of the following heterocycles includes one or more nitrogen atoms. Classify each nitrogen atom as strongly basic or weakly basic, according to the availability of its lone pair of electrons.
(a)
(b)
(c)
1425
views
Textbook Question
Some of the following compounds show aromatic properties, and others do not.
1. Predict which ones are likely to be aromatic, and explain why they are aromatic.
2. Predict which nitrogen atoms are more basic than water and which are less basic.
(f)
503
views