Textbook Question
The structures of four useful polymers are shown, together with some of their best-known products. In each case,
(i) determine the kind of polymer (polyamide, polyester, etc.).
(c)
(d)
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Ch. 21 - Carboxylic Acid Derivatives
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 21, Problem 71a,b
Macrolide antibiotics, including erythromycin and azithromycin (Zithromax®), contain a large ring lactone. One of the largest ever reported is Gargantulide A, the structure of which was determined by the research group of Prof. William Gerwick of the Scripps Institution of Oceanography (Organic Letters, 2015, 17, 1377–1380). Isolated from a Streptomyces bacterium, it kills pathogenic bacteria like MRSA and Clostridium difficile, but it proved too toxic to the test animals to continue further testing.
(a) Identify the lactone that makes this a macrolide structure.
(b) How many rings does this structure contain? How many atoms are in the largest ring?
Verified step by step guidance1
Examine the structure of Gargantulide A provided in the image. A lactone is a cyclic ester, which contains a carbonyl group (C=O) bonded to an oxygen atom within a ring structure. Identify the lactone group in the molecule by locating the ester functional group within a ring.
The term 'macrolide' refers to a large ring lactone. In Gargantulide A, the largest ring containing a lactone group is the macrolide structure. Locate the largest ring in the molecule that contains the lactone functional group.
Count the number of rings present in the structure. Look for all cyclic structures, including the macrolide ring and any other smaller rings present in the molecule.
Determine the number of atoms in the largest ring. To do this, count all the atoms (carbon, oxygen, etc.) that form the perimeter of the macrolide ring.
Summarize the findings: Identify the lactone group that makes this a macrolide structure, state the total number of rings in the molecule, and specify the number of atoms in the largest ring.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Macrolide Structure
Macrolides are a class of antibiotics characterized by a large lactone ring, typically containing 14 to 16 atoms. The lactone is formed through the esterification of a hydroxy acid, which is crucial for the antibiotic's mechanism of action. Understanding the structure of macrolides, including the specific lactone present in Gargantulide A, is essential for identifying its properties and functions.
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Ring Structure in Organic Chemistry
In organic chemistry, the term 'ring structure' refers to a cyclic arrangement of atoms within a molecule. The number of rings and their sizes can significantly influence the chemical properties and biological activity of a compound. For Gargantulide A, determining the number of rings and the size of the largest ring is vital for understanding its structural complexity and potential interactions with biological targets.
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Antibiotic Mechanism of Action
Antibiotics like macrolides function by inhibiting bacterial growth through various mechanisms, such as blocking protein synthesis. Understanding how Gargantulide A interacts with bacterial cells, particularly its effectiveness against pathogens like MRSA, is crucial for evaluating its potential therapeutic applications. However, the toxicity observed in test animals highlights the importance of balancing efficacy with safety in drug development.
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Related Practice
Textbook Question
An unknown compound gives a mass spectrum with a weak molecular ion at m/z 113 and a prominent ion at m/z 68. Its NMR and IR spectra are shown here. Determine the structure, and show how it is consistent with the observed absorptions. Propose a favorable fragmentation to explain the prominent MS peak at m/z 68.
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Textbook Question
The structures of four useful polymers are shown, together with some of their best-known products. In each case,
(i) Determine the kind of polymer (polyamide, polyester, etc.).
(ii) Draw the structures of the monomers that would be released by complete hydrolysis.
(iii) Suggest what monomers or stable derivatives of the monomers might be used to make these polymers.
(b)
1
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