Textbook Question
Show how you would convert
a. oct-3-yne to cis-oct-3-ene.
b. pent-2-yne to trans-pent-2-ene.
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Ch.9 - Alkynes
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 9, Problem 13
The fragrance of (Z)-1-phenylhex-2-en-1-ol resembles that of roses, with a delicate citrus edge. Show how you would synthesize this compound from benzaldehyde (PhCHO) and any other reagents you need.
Verified step by step guidance1
Step 1: Begin by identifying the target molecule, (Z)-1-phenylhex-2-en-1-ol. This compound contains a phenyl group attached to a hex-2-en-1-ol backbone with a Z-configuration at the double bond. The starting material is benzaldehyde (PhCHO), which provides the phenyl group.
Step 2: Perform a Wittig reaction to introduce the alkene functionality. React benzaldehyde (PhCHO) with a Wittig reagent, such as hexylidene triphenylphosphorane, to form the hex-2-en-1-al intermediate. Ensure that the reaction conditions favor the Z-configuration of the double bond.
Step 3: Reduce the hex-2-en-1-al intermediate to the corresponding alcohol, hex-2-en-1-ol. Use a mild reducing agent such as sodium borohydride (NaBH₄) to selectively reduce the aldehyde group without affecting the double bond.
Step 4: Verify the stereochemistry of the product to ensure the Z-configuration of the double bond is retained. This can be confirmed using spectroscopic techniques such as NMR or IR.
Step 5: Purify the final product, (Z)-1-phenylhex-2-en-1-ol, using techniques such as column chromatography to remove any impurities and isolate the desired compound.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Aldol Condensation
Aldol condensation is a key reaction in organic chemistry where two carbonyl compounds, typically aldehydes or ketones, react in the presence of a base to form a β-hydroxy aldehyde or ketone. This reaction is crucial for synthesizing larger molecules and can lead to the formation of enones or enals upon dehydration. In the context of synthesizing (Z)-1-phenylhex-2-en-1-ol, an aldol reaction can be employed to create the necessary carbon skeleton from benzaldehyde.
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Stereochemistry
Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the synthesis of (Z)-1-phenylhex-2-en-1-ol, understanding stereochemistry is essential to ensure the correct geometric isomer is produced, as the 'Z' configuration indicates specific spatial arrangements of substituents around the double bond. This concept is vital for predicting the properties and reactivity of the synthesized compound.
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Reduction Reactions
Reduction reactions involve the gain of electrons or the decrease in oxidation state of a molecule, often through the addition of hydrogen or the removal of oxygen. In the synthesis of (Z)-1-phenylhex-2-en-1-ol, a reduction step may be necessary to convert an intermediate carbonyl compound into the corresponding alcohol. Understanding various reducing agents, such as lithium aluminum hydride or sodium borohydride, is important for selecting the appropriate method for achieving the desired product.
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Related Practice
Textbook Question
Show how you would convert
c. cis-cyclodecene to trans-cyclodecene.
1223
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Textbook Question
Show how you would convert
d. but-1-yne to cis-hex-3-ene.
1166
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Textbook Question
Propose a mechanism for the entire reaction of pent-1-yne with 2 moles of HBr. Show why Markovnikov's rule should be observed in both the first and second additions of HBr.
1345
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Textbook Question
In the addition of just 1 mole of bromine to 1 mole of hex-1-yne, should the hex-1-yne be added to a bromine solution or should the bromine be added to the hex-1-yne? Explain your answer.
1236
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Textbook Question
Predict the major product(s) of the following reactions:
a. phenylacetylene + 2 HBr
b. hex-1-yne + 2 HCl
1622
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