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Ch. 16 - Aromatic Compounds
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh. 16 - Aromatic CompoundsProblem 35n,o
Chapter 16, Problem 35n,o

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.
(n)
(o)

Verified step by step guidance
1
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 the first compound (image n). The structure is cyclic and contains alternating double bonds, indicating conjugation. The carbonyl group (C=O) does not contribute to the π-electron count directly. Count the π-electrons in the conjugated system to check if it satisfies Huckel's rule.
Step 3: Analyze the second compound (image o). This structure is also cyclic and contains alternating double bonds, indicating conjugation. Similar to the first compound, the carbonyl group does not contribute to the π-electron count directly. Count the π-electrons in the conjugated system to check if it satisfies Huckel's rule.
Step 4: Determine the planarity of each compound. Both compounds appear to be planar due to their cyclic conjugated systems, which allow for delocalization of π-electrons. Planarity is essential for aromaticity.
Step 5: Conclude aromaticity based on the π-electron count and Huckel's rule. If the π-electron count in the conjugated system of each compound satisfies the (4n + 2) rule, the compound is aromatic. Otherwise, it is not aromatic.

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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 considered aromatic, it must be cyclic, planar, and follow Hückel's rule, which states that it must have a total of 4n + 2 π electrons, where n is a non-negative integer.
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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 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 refers to the overlap of p-orbitals across adjacent atoms, allowing for the delocalization of π electrons. In aromatic compounds, conjugation is essential as it contributes to the stability and unique chemical properties of the molecule. The presence of conjugated double bonds in a cyclic structure is a key factor in determining aromaticity.
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Related Practice
Textbook Question

The benzene ring alters the reactivity of a neighboring group in the benzylic position much as a double bond alters the reactivity of groups in the allylic position.

Benzylic cations, anions, and radicals are all more stable than simple alkyl intermediates.

a. Use resonance forms to show the delocalization (over four carbon atoms) of the unpaired electron of the benzyl radical.

3
views
Textbook Question

The benzene ring alters the reactivity of a neighboring group in the benzylic position much as a double bond alters the reactivity of groups in the allylic position.


Benzylic cations, anions, and radicals are all more stable than simple alkyl intermediates.

a. Use resonance forms to show the delocalization (over four carbon atoms) of the positive charge of the benzyl cation.

5
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.

(m)

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)

1
views
Textbook Question

The benzene ring alters the reactivity of a neighboring group in the benzylic position much as a double bond alters the reactivity of groups in the allylic position.

Benzylic cations, anions, and radicals are all more stable than simple alkyl intermediates.

a. Use resonance forms to show the delocalization (over four carbon atoms) of the negative charge of the benzyl anion.

7
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)