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Ch. 2 - Acids and Bases; Functional Groups
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh. 2 - Acids and Bases; Functional GroupsProblem 22c,d
Chapter 2, Problem 22c,d

Choose the more basic member of each pair of isomers, and show why the base you chose is more basic.
c.
d.

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1
Identify the functional groups in each isomer. In the first pair, both structures contain a lactam and a lactone group, but differ in the position of the nitrogen and oxygen atoms. In the second pair, both structures contain a nitro group and a phenoxide ion, but differ in the position of the nitro group relative to the phenoxide ion.
For the first pair, consider the resonance stabilization of the negative charge on the oxygen atom. The structure where the negative charge is more delocalized will be less basic, as the charge is more stabilized.
In the first pair, analyze the resonance structures. The isomer with the nitrogen atom adjacent to the carbonyl group can delocalize the negative charge more effectively through resonance, making it less basic.
For the second pair, consider the electron-withdrawing effect of the nitro group. The nitro group is a strong electron-withdrawing group, and its position relative to the phenoxide ion will affect the basicity.
In the second pair, the isomer with the nitro group in the para position relative to the phenoxide ion will have a greater electron-withdrawing effect, stabilizing the negative charge more and making it less basic. Therefore, the ortho position isomer is more basic.

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Key Concepts

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

Basicity in Organic Chemistry

Basicity refers to the ability of a compound to accept protons. In organic chemistry, the basicity of a molecule is often influenced by the presence of electron-donating groups and the availability of lone pairs on atoms like nitrogen. A more basic compound will have a higher tendency to accept protons due to increased electron density or stabilization of the resulting cation.
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Resonance Stabilization

Resonance stabilization occurs when a molecule can distribute its electrons across multiple atoms, reducing the energy of the molecule. In the context of basicity, resonance can stabilize the negative charge on a conjugate base, making the original molecule less basic. The more resonance structures available, the more stable the molecule, often leading to decreased basicity.
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Inductive Effect

The inductive effect involves the transmission of charge through a chain of atoms in a molecule, affecting its acidity or basicity. Electron-withdrawing groups can decrease basicity by pulling electron density away from the basic site, while electron-donating groups can increase basicity by enhancing electron density. This effect is crucial in determining the relative basicity of isomers.
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Related Practice
Textbook Question

In the following acid–base reactions,

1. draw Lewis structures of the reactants and the products.

2. determine which species are acting as electrophiles (acids) and which are acting as nucleophiles (bases).

3. use the curved-arrow formalism to show the movement of electron pairs in these ­reactions, as well as the imaginary movement in the resonance hybrids of the products.

4. indicate which reactions are best termed Brønsted–Lowry acid–base reactions.

(a)

1499
views
Textbook Question

Choose the more basic member of each pair of isomers, and show why the base you chose is more basic.

e.

852
views
Textbook Question

In the following acid–base reactions,

1. draw Lewis structures of the reactants and the products.

2. determine which species are acting as electrophiles (acids) and which are acting as nucleophiles (bases).

3. use the curved-arrow formalism to show the movement of electron pairs in these ­reactions, as well as the imaginary movement in the resonance hybrids of the products.

4. indicate which reactions are best termed Brønsted–Lowry acid–base reactions.

(b)

1407
views
Textbook Question

Choose the more basic member of each pair of isomers, and show why the base you chose is more basic.

(a)

(b)

1168
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Textbook Question

Choose the more acidic member of each pair of isomers, and show why the acid you chose is more acidic.

(d)

(e)

764
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Textbook Question

Choose the more acidic member of each pair of isomers, and show why the acid you chose is more acidic.

(f)

(g)

601
views