Textbook Question
When combining isoprene equivalents, IPP is never the electrophile. Why might this be? What is special about DPP that allows it to function better as an electrophile? [Draw the carbocation that each becomes.]
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Ch. 8 - Alkenes I: Properties and Electrophilic Additions
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 7, Problem 44
Suggest a mechanism for the synthesis of farnesol beginning with IPP and DPP.
Verified step by step guidance1
Step 1: Identify the starting materials. IPP (isopentenyl pyrophosphate) and DPP (dimethylallyl pyrophosphate) are both five-carbon isoprenoid units. Farnesol is a 15-carbon compound, so the synthesis involves combining three isoprenoid units.
Step 2: Perform the first coupling reaction. DPP acts as the electrophile, and IPP acts as the nucleophile. The pyrophosphate group of DPP is displaced, forming a 10-carbon intermediate called geranyl pyrophosphate (GPP). This reaction is catalyzed by geranyl pyrophosphate synthase.
Step 3: Perform the second coupling reaction. GPP now acts as the electrophile, and another molecule of IPP acts as the nucleophile. The pyrophosphate group of GPP is displaced, forming a 15-carbon intermediate called farnesyl pyrophosphate (FPP). This reaction is catalyzed by farnesyl pyrophosphate synthase.
Step 4: Hydrolyze the pyrophosphate group of FPP. The pyrophosphate group is removed, yielding farnesol. This step is typically catalyzed by a phosphatase enzyme.
Step 5: Verify the structure of farnesol. Farnesol contains three isoprenoid units, two double bonds in the trans configuration, and a terminal hydroxyl group. Ensure the stereochemistry and functional groups match the target molecule.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Isoprenoid Biosynthesis
Isoprenoid biosynthesis is a fundamental pathway in organic chemistry that involves the formation of isoprene units, which are the building blocks of many natural products. In this context, isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DPP) are key intermediates that undergo condensation reactions to form larger isoprenoid compounds, such as farnesol.
Condensation Reactions
Condensation reactions are chemical processes where two molecules combine to form a larger molecule, releasing a small molecule, often water. In the synthesis of farnesol, IPP and DPP undergo a series of condensation reactions, where they join together to create longer carbon chains, ultimately leading to the formation of farnesol through sequential addition of isoprene units.
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Farnesol Structure and Function
Farnesol is a sesquiterpene alcohol with a specific structure that includes three isoprene units. Understanding its structure is crucial for predicting its reactivity and potential applications, such as in fragrance and flavor industries. The synthesis of farnesol from IPP and DPP highlights the importance of structural features in organic compounds and their biological significance.
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Related Practice
Textbook Question
Ethers can be synthesized by substituting ethanol for water in the acid-catalyzed hydration reaction. Suggest an arrow-pushing mechanism which accounts for the formation of the ethyl ether under these conditions.
Textbook Question
Which of the following carbocations would you expect to rearrange? If you expect rearrangement, draw the carbocation you expect to form and the mechanism by which it will form.
(a)
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Textbook Question
Which of the following carbocations would you expect to rearrange? If you expect rearrangement, draw the carbocation you expect to form and the mechanism by which it will form.
(c)
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Textbook Question
Provide the alkene that would give the following alcohols under acid-catalyzed hydration conditions.
(a)
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Textbook Question
Which of the following carbocations would you expect to rearrange? If you expect rearrangement, draw the carbocation you expect to form and the mechanism by which it will form.
(b)
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