Textbook Question
Show how the substituents containing the azo group (N=N) can facilitate both electrophilic and nucleophilic aromatic substitution.
(a)
1
views
Ch. 19 - Amines
Wade9th EditionOrganic ChemistryISBN: 9780135213728
Not the one you use?Change textbookSelect a different textbook
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 19, Problem 64b
Show how the substituents containing the azo group (N=N) can facilitate both electrophilic and nucleophilic aromatic substitution.
(b) 
Verified step by step guidance1
Step 1: Understand the role of the azo group (N=N) in aromatic substitution. The azo group is an electron-withdrawing group due to the resonance and inductive effects of the nitrogen atoms. This influences the reactivity of the aromatic ring in both electrophilic and nucleophilic aromatic substitution reactions.
Step 2: For electrophilic aromatic substitution, the azo group deactivates the aromatic ring by withdrawing electron density. This makes the ring less reactive toward electrophiles. However, the azo group can direct substitution to specific positions (meta-directing) due to its electron-withdrawing nature.
Step 3: For nucleophilic aromatic substitution, the electron-withdrawing nature of the azo group increases the susceptibility of the aromatic ring to attack by nucleophiles. This is particularly effective when there are additional electron-withdrawing groups (e.g., fluorine) on the ring, which stabilize the intermediate formed during the substitution process.
Step 4: Analyze the reaction provided in the image. The fluorine atom on the aromatic ring is an electron-withdrawing group, and the azo group further enhances the ring's susceptibility to nucleophilic attack. The diethylamine (Et2NH) acts as a nucleophile, replacing the fluorine atom via nucleophilic aromatic substitution.
Step 5: The product shows the diethylamino group (Et2N) attached to the aromatic ring, indicating successful nucleophilic substitution. The azo group remains intact, and the tert-butyl carbamate group (O-t-Bu) is unaffected, serving as a protecting group for the azo functionality.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
5mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Azo Group
The azo group (N=N) is a functional group characterized by a nitrogen-nitrogen double bond. It is commonly found in azo compounds, which are often brightly colored and used in dyes. The presence of the azo group can significantly influence the reactivity of aromatic compounds, making them more susceptible to both electrophilic and nucleophilic substitution reactions due to the resonance stabilization it provides.
Recommended video:
Guided course
04:42
Sequence Groups
Electrophilic Aromatic Substitution (EAS)
Electrophilic aromatic substitution is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. The presence of electron-donating groups, such as those attached to an azo group, can enhance the electron density of the aromatic system, making it more reactive towards electrophiles. This process is crucial for synthesizing various aromatic compounds and understanding the reactivity patterns of substituted aromatics.
Recommended video:
Guided course
03:07EAS Review
Nucleophilic Aromatic Substitution (NAS)
Nucleophilic aromatic substitution occurs when a nucleophile attacks an aromatic ring, typically at a carbon atom that is bonded to a leaving group. The presence of electron-withdrawing groups, such as the azo group, can stabilize the negative charge developed during the reaction, facilitating the substitution process. This reaction is particularly important in the synthesis of complex organic molecules and in understanding the behavior of aromatic systems under different conditions.
Recommended video:
Guided course
02:10NAS in the addition-elimination pathway
Related Practice
Textbook Question
Reductive amination of aldehydes and ketones is a versatile method for attaching alkyl groups to amines, but the alkyl group is restricted to a 1° or 2° carbon by this method. Prof. Phil Baran of Scripps Research Institute has reported (Science, 2015, 348 (6237), 886–891) a novel way to reduce an aromatic nitro group and add the resulting amine to an alkene so that the aromatic amine is bonded to a 3° carbon—all in a continuous sequence of reactions.
For example:
Predict the products using these starting materials, all of which are reported in this paper.
(c)
(d)
3
views
Textbook Question
Macrolide antibiotics all have large rings (macrocycle) in which an ester makes the ring; a cyclic ester is termed a lactone. One example is erythromycin A, first isolated from soil bacteria in the 1950s. Over time, some pathogenic bacteria have developed resistance to erythromycin by evolving an enzymatic mechanism to cleave the macrocycle at the ketone. To counter this resistance, chemists modified the erythromycin structure to replace the ketone with an amine that the bacteria could not detoxify. This modified antibiotic, azithromycin, trade name Zithromax®, is one of the most prescribed drugs in the world for respiratory infections.
(a) Identify the lactone group in each structure that merits the classification as macrolides.
(b) Two groups are circled. What type of functional group are they? Explain.
1
views
Textbook Question
Basicity depends on availability of an electron pair to bond a proton. Correlate structural effects in these amines with their basicities.
(c) The pKb of this compound is −2.3, making it not only a stronger base than a typical aniline, but even stronger than hydroxide ion. Explain its remarkable basicity.
1
views
Textbook Question
Macrolide antibiotics all have large rings (macrocycle) in which an ester makes the ring; a cyclic ester is termed a lactone. One example is erythromycin A, first isolated from soil bacteria in the 1950s. Over time, some pathogenic bacteria have developed resistance to erythromycin by evolving an enzymatic mechanism to cleave the macrocycle at the ketone. To counter this resistance, chemists modified the erythromycin structure to replace the ketone with an amine that the bacteria could not detoxify. This modified antibiotic, azithromycin, trade name Zithromax®, is one of the most prescribed drugs in the world for respiratory infections.
(c) Identify the ketone in erythromycin targeted by bacteria as the site for detoxification.
(d) Identify the amine in azithromycin. What type of amine is it?
5
views