Textbook Question
Show how you would use a Suzuki reaction to synthesize the following biaryl compound. As starting materials, you may use the two indicated compounds, plus any additional reagents you need.
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Ch. 17 - Reactions of Aromatic Compounds
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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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 17, Problem 78a
Phenolphthalein, a common nonprescription laxative, is also an acid–base indicator that is colorless in acid and red in base. Phenolphthalein is synthesized by the acid-catalyzed reaction of phthalic anhydride with 2 equivalents of phenol.
a. Propose a mechanism for the synthesis of phenolphthalein.
Verified step by step guidance1
Step 1: Protonation of phthalic anhydride - The reaction begins with the acid catalyst (H⁺) protonating one of the carbonyl oxygen atoms in phthalic anhydride. This increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack.
Step 2: Nucleophilic attack by phenol - The phenol molecule acts as a nucleophile, attacking the electrophilic carbonyl carbon of the protonated phthalic anhydride. This forms a tetrahedral intermediate.
Step 3: Loss of water and formation of an ester bond - The tetrahedral intermediate collapses, expelling a molecule of water and forming an ester bond between the phenol and phthalic anhydride.
Step 4: Second nucleophilic attack by phenol - A second molecule of phenol attacks the remaining carbonyl group of the phthalic anhydride, forming another tetrahedral intermediate. This step is similar to the first nucleophilic attack.
Step 5: Cyclization and formation of phenolphthalein - The intermediate undergoes cyclization, where the aromatic ring of phenol attacks the carbonyl group, forming a new carbon-carbon bond. This results in the final structure of phenolphthalein, which is stabilized by resonance.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Catalyzed Reactions
Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In the synthesis of phenolphthalein, sulfuric acid acts as a catalyst, facilitating the reaction between phthalic anhydride and phenol. This process typically involves protonation of the reactants, making them more reactive and promoting the formation of the desired product.
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03:09
Acid Catalyzed
Phenol and Its Derivatives
Phenol is a simple aromatic compound with a hydroxyl (-OH) group attached to a benzene ring. In the synthesis of phenolphthalein, two equivalents of phenol react with phthalic anhydride to form a complex structure. Understanding the reactivity of phenol and its ability to undergo electrophilic substitution is crucial for grasping how phenolphthalein is formed.
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02:27Identify the most acidic phenol
Color Change in Acid-Base Indicators
Phenolphthalein is an acid-base indicator that exhibits a distinct color change depending on the pH of the solution. It is colorless in acidic conditions and turns red in basic conditions due to the formation of a red dianion. This property is essential for its use in titrations and pH testing, highlighting the relationship between molecular structure and colorimetric response.
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02:49The Lewis definition of acids and bases.
Related Practice
Textbook Question
The antioxidants BHA and BHT are commonly used as food preservatives. Show how BHA and BHT can be made from phenol and hydroquinone
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Textbook Question
Phenolphthalein, a common nonprescription laxative, is also an acid–base indicator that is colorless in acid and red in base. Phenolphthalein is synthesized by the acid-catalyzed reaction of phthalic anhydride with 2 equivalents of phenol.
b. Propose a mechanism for the conversion of phenolphthalein to its red dianion in base.
c. Use resonance structures to show that the two phenolic oxygen atoms are equivalent (each with half a negative charge) in the red phenolphthalein dianion.
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Textbook Question
A common illicit synthesis of methamphetamine involves an interesting variation of the Birch reduction. A solution of ephedrine in alcohol is added to liquid ammonia, followed by several pieces of lithium metal. The Birch reduction usually reduces the aromatic ring (Section 17-14C), but in this case it eliminates the hydroxy group of ephedrine to give methamphetamine. Propose a mechanism, similar to that for the Birch reduction, to explain this unusual course of the reaction.
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