Textbook Question
Show how you would convert propan-1-ol to the following compounds using tosylate intermediates. You may use whatever additional reagents are needed.
c. CH3CH2CH2OCH2CH3, ethyl proyl ether
d. CH3CH2CH2CN, butyronitrile
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Ch.11 - Reactions of Alcohols
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 11, Problem 11a,b
Predict the products of the following reactions.
(a) cyclohexylmethanol + TsCl/pyridine
(b) product of (a) + LiAlH4
Verified step by step guidance1
Step 1: Analyze the reaction in part (a). Cyclohexylmethanol reacts with TsCl (tosyl chloride) in the presence of pyridine. Tosyl chloride is commonly used to convert alcohols into tosylates, which are excellent leaving groups. The hydroxyl group (-OH) of cyclohexylmethanol will be replaced by a tosyl group (-OTs). This occurs via nucleophilic substitution, where pyridine acts as a base to neutralize the HCl byproduct.
Step 2: Write the chemical transformation for part (a). Cyclohexylmethanol (C6H11CH2OH) reacts with TsCl to form cyclohexylmethyl tosylate (C6H11CH2OTs). The tosyl group is represented as -SO2C6H4CH3. This step involves the formation of a new bond between the oxygen atom of the alcohol and the sulfur atom of the tosyl group.
Step 3: Analyze the reaction in part (b). The product from part (a), cyclohexylmethyl tosylate, reacts with LiAlH4 (lithium aluminum hydride). LiAlH4 is a strong reducing agent that can reduce alkyl tosylates to alkanes. In this case, the tosyl group (-OTs) will be removed, and the hydrogen atoms from LiAlH4 will replace it, forming cyclohexylmethane.
Step 4: Write the chemical transformation for part (b). Cyclohexylmethyl tosylate (C6H11CH2OTs) reacts with LiAlH4 to form cyclohexylmethane (C6H11CH3). This reduction involves the cleavage of the C-O bond and the addition of hydrogen atoms.
Step 5: Summarize the overall reaction sequence. In part (a), cyclohexylmethanol is converted into cyclohexylmethyl tosylate via reaction with TsCl/pyridine. In part (b), cyclohexylmethyl tosylate is reduced by LiAlH4 to form cyclohexylmethane. These steps demonstrate the use of tosylation to activate an alcohol for subsequent reduction.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
TsCl and Pyridine Reaction
The reaction of alcohols with tosyl chloride (TsCl) in the presence of a base like pyridine converts the alcohol into a tosylate, which is a better leaving group. This transformation facilitates subsequent nucleophilic substitution reactions, allowing for the formation of more reactive intermediates that can undergo further reactions.
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Nucleophilic Substitution
Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the context of the reaction products, the tosylate formed from cyclohexylmethanol can undergo substitution with a nucleophile, such as hydride from LiAlH4, leading to the formation of an alcohol or alkane.
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LiAlH4 as a Reducing Agent
Lithium aluminum hydride (LiAlH4) is a strong reducing agent commonly used in organic chemistry to reduce carbonyl compounds and other electrophiles. In this case, it can reduce the tosylate product from the first reaction back to an alcohol, effectively restoring the hydroxyl group and completing the transformation of the original alcohol.
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Related Practice
Textbook Question
Show how you would convert propan-1-ol to the following compounds using tosylate intermediates. You may use whatever additional reagents are needed.
a. 1-bromopropane
b. propan-1-amine, CH3CH2CH2NH2
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Textbook Question
Predict the major products of the following reactions.
(d) the tosylate of cyclohexylmethanol + excess NH3
(e) n-butyl tosylate + sodium acetylide, H–C≡C:– +Na
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Textbook Question
Predict the products of the following reactions.
(c) 1-methylcyclohexanol + H2SO4, heat
(d) product of (c) + H2, Pt
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Textbook Question
Propose a mechanism for the reaction of
(a) 1-methylcyclohexanol with HBr to form 1-bromo-1-methylcyclohexane.
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Textbook Question
The reaction of tert-butyl alcohol with concentrated HCl goes by the SN1 mechanism. Write a mechanism for this reaction.
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