Textbook Question
Tyramine is an alkaloid found in mistletoe and ripe cheese. Dopamine is a neurotransmitter involved in the regulation of the central nervous system.
a. How can tyramine be prepared from b-phenylethylamine?
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Ch. 18 - Reactions of Benzene and Substituted Benzenes
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
Chapter 19, Problem 99
Explain why hydroxide ion catalyzes the reaction of piperidine with 2,4-dinitroanisole but has no effect on the reaction of piperidine with 1-chloro-2,4-dinitrobenzene.
Verified step by step guidance1
Step 1: Understand the role of hydroxide ion in catalysis. Hydroxide ion (OH⁻) is a strong nucleophile and base, which can deprotonate certain compounds or participate in nucleophilic substitution reactions. Its catalytic effect depends on the chemical structure and reactivity of the substrate.
Step 2: Analyze the reaction of piperidine with 2,4-dinitroanisole. The methoxy group (-OCH₃) in 2,4-dinitroanisole is an electron-donating group, which makes the aromatic ring less electrophilic. However, the presence of two nitro groups (-NO₂) strongly activates the ring towards nucleophilic aromatic substitution (NAS). Hydroxide ion can enhance the reaction by deprotonating piperidine, increasing its nucleophilicity and facilitating the attack on the activated aromatic ring.
Step 3: Examine the reaction of piperidine with 1-chloro-2,4-dinitrobenzene. The chlorine atom (-Cl) is a good leaving group, and the two nitro groups (-NO₂) strongly activate the aromatic ring for nucleophilic aromatic substitution. Piperidine itself is sufficiently nucleophilic to react with 1-chloro-2,4-dinitrobenzene without requiring additional catalysis by hydroxide ion. Thus, hydroxide ion has no significant effect on this reaction.
Step 4: Compare the two reactions. In the case of 2,4-dinitroanisole, the methoxy group reduces the electrophilicity of the aromatic ring, making the reaction slower without hydroxide ion catalysis. In contrast, 1-chloro-2,4-dinitrobenzene has a highly activated ring due to the nitro groups and a good leaving group (chlorine), allowing the reaction to proceed efficiently without hydroxide ion.
Step 5: Conclude the explanation. Hydroxide ion catalyzes the reaction with 2,4-dinitroanisole by increasing the nucleophilicity of piperidine, overcoming the reduced electrophilicity caused by the methoxy group. However, it has no effect on the reaction with 1-chloro-2,4-dinitrobenzene because the substrate is already highly reactive due to the nitro groups and the presence of a good leaving group.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilicity
Nucleophilicity refers to the ability of a nucleophile, such as the hydroxide ion (OH-), to donate an electron pair to an electrophile. In the context of the reactions mentioned, piperidine acts as a nucleophile, and its reactivity can be influenced by the nature of the electrophile. The presence of electron-withdrawing groups, like the nitro groups in 2,4-dinitroanisole, enhances the electrophilicity of the substrate, making it more susceptible to nucleophilic attack.
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Nucleophilic Addition
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (EAS) is a fundamental reaction mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. In the case of 1-chloro-2,4-dinitrobenzene, the chlorine atom is a good leaving group, but the electron-withdrawing nitro groups stabilize the aromatic system, making it less reactive towards nucleophiles like hydroxide. This contrasts with 2,4-dinitroanisole, where the ether group can be protonated, facilitating nucleophilic attack.
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Base Catalysis
Base catalysis involves the acceleration of a reaction by a base, which can deprotonate a substrate or activate a nucleophile. In the reaction of piperidine with 2,4-dinitroanisole, hydroxide ion acts as a base, enhancing the nucleophilicity of piperidine. However, in the case of 1-chloro-2,4-dinitrobenzene, the reaction does not benefit from hydroxide catalysis due to the stability of the aromatic system and the nature of the leaving group, which does not require base assistance for the reaction to proceed.
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Related Practice
Textbook Question
Describe how 3-methyl-1-phenyl-3-pentanol can be prepared from benzene. You can use any inorganic reagents and solvents, and any organic reagents provided they contain no more than two carbons.
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Textbook Question
a. Explain why the following reaction leads to the products shown:
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Textbook Question
Propose a mechanism for each of the following reactions:
b.
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