Textbook Question
Draw a mechanism for the reaction of propanoyl chloride with 2 moles of phenylmagnesium bromide.
1241
views
Ch. 21 - Carboxylic Acid Derivatives
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 21, Problem 26
Draw a mechanism for the acidic hydrolysis of the magnesium salt shown below to acetophenone.
Verified step by step guidance1
Step 1: Identify the magnesium salt structure. The compound shown is a magnesium salt of an imine, where the nitrogen is bonded to magnesium iodide (MgI). The carbon-nitrogen double bond is polarized, with the nitrogen carrying a lone pair and partial negative charge.
Step 2: Protonation of the imine nitrogen. In acidic conditions, a proton (H⁺) from the acid will attack the lone pair on the nitrogen, leading to the formation of a positively charged iminium ion. This step increases the electrophilicity of the carbon atom in the C=N bond.
Step 3: Nucleophilic attack by water. Water, acting as a nucleophile, attacks the electrophilic carbon atom of the iminium ion. This results in the formation of a tetrahedral intermediate, where the carbon is bonded to both the nitrogen and a hydroxyl group.
Step 4: Elimination of the nitrogen group. The tetrahedral intermediate undergoes rearrangement, leading to the cleavage of the C-N bond. The nitrogen group is eliminated as ammonia (NH₃), and the carbon is left with a hydroxyl group.
Step 5: Formation of acetophenone. The hydroxyl group on the carbon undergoes tautomerization or dehydration, depending on the reaction conditions, to form the final product, acetophenone (C₆H₅COCH₃).
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
7mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acidic Hydrolysis
Acidic hydrolysis is a chemical reaction where a compound reacts with water in the presence of an acid, leading to the cleavage of bonds and the formation of new products. In this context, the magnesium salt undergoes hydrolysis to yield acetophenone, facilitated by the protonation of the imine nitrogen, which enhances its electrophilicity and promotes nucleophilic attack by water.
Recommended video:
0:55
Hydrolysis of Nucleosides Concept 1
Mechanism of Nucleophilic Attack
The mechanism of nucleophilic attack involves the interaction of a nucleophile with an electrophile, resulting in the formation of a new bond. In the case of the magnesium salt, water acts as the nucleophile, attacking the carbon atom of the imine group after the nitrogen is protonated, leading to the formation of an intermediate that eventually rearranges to produce acetophenone.
Recommended video:
Guided course
08:27Nucleophilic Addition
Role of Magnesium Salt
The magnesium salt in this reaction serves as a Lewis acid, facilitating the hydrolysis process. It stabilizes the imine structure and enhances the electrophilic character of the carbon-nitrogen double bond, making it more susceptible to nucleophilic attack by water. This role is crucial for the successful conversion of the magnesium salt to acetophenone.
Recommended video:
Guided course
02:32Synthesis of Amides
Related Practice
Textbook Question
Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(b) heptan-4-ol.
598
views
Textbook Question
In which step(s) of the hydride reduction of an ester does the compound undergo reduction? (Hint: Count the bonds to oxygen.)
995
views
Textbook Question
Propose a mechanism for the reduction of octanoyl chloride by lithium aluminum hydride.
857
views
Textbook Question
The mechanism for acidic hydrolysis of a nitrile resembles the basic hydrolysis, except that the nitrile is first protonated, activating it toward attack by a weak nucleophile (water). Under acidic conditions, the proton transfer (tautomerism) involves protonation on nitrogen followed by deprotonation on oxygen. Propose a mechanism for the acid-catalyzed hydrolysis of benzonitrile to benzamide.
778
views
Textbook Question
Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(a) 4-phenylheptan-4-ol.
1205
views