Ch. 14 - Ethers, Epoxides, and Thioethers

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch. 14 - Ethers, Epoxides, and Thioethers

Problem 8

Chapter 14, Problem 8

Propose a Williamson synthesis of 3-butoxy-1,1-dimethylcyclohexane from 3,3-dimethyl-cyclohexanol and butan-1-ol.

Verified step by step guidance

Identify the target ether product: The target compound is 3-butoxy-1,1-dimethylcyclohexane, which is an ether. Williamson synthesis involves the reaction of an alkoxide ion with an alkyl halide to form an ether.

Determine the two components needed for the Williamson synthesis: The ether can be formed by reacting an alkoxide derived from 3,3-dimethylcyclohexanol with an alkyl halide derived from butan-1-ol.

Convert 3,3-dimethylcyclohexanol into its alkoxide: React 3,3-dimethylcyclohexanol with a strong base such as sodium hydride (NaH) or sodium metal (Na) to deprotonate the alcohol and form the alkoxide ion \( \text{(3,3-dimethylcyclohexoxide)} \).

Prepare the alkyl halide from butan-1-ol: React butan-1-ol with a halogenating agent such as phosphorus tribromide (PBr₃) or thionyl chloride (SOCl₂) to convert it into 1-bromobutane or 1-chlorobutane.

Perform the Williamson synthesis: React the 3,3-dimethylcyclohexoxide ion with the alkyl halide (e.g., 1-bromobutane) in an aprotic solvent such as dimethyl sulfoxide (DMSO) or acetone. This reaction proceeds via an \( S_N2 \) mechanism, resulting in the formation of 3-butoxy-1,1-dimethylcyclohexane.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Williamson Ether Synthesis

The Williamson ether synthesis is a method for creating ethers through the reaction of an alkoxide ion with a primary alkyl halide. This reaction typically involves the nucleophilic substitution mechanism (SN2), where the alkoxide acts as a nucleophile, attacking the electrophilic carbon of the alkyl halide, resulting in the formation of an ether.

Nucleophilic Substitution Mechanism

Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the case of the Williamson synthesis, the nucleophile is the alkoxide ion, and the leaving group is typically a halide. The mechanism can be either SN1 or SN2, with SN2 being preferred for primary alkyl halides due to steric accessibility.

Sterics and Reactivity

Sterics refers to the spatial arrangement of atoms in a molecule and how this affects reactivity. In the Williamson synthesis, steric hindrance can influence the choice of alkyl halide; primary halides are more reactive in SN2 reactions than secondary or tertiary halides. Understanding sterics is crucial for predicting the outcome of the synthesis and ensuring successful ether formation.

Recommended video:

Guided course

02:53

Understanding steric effects.

Related Practice

Textbook Question

Show how the following ethers might be synthesized using (1) alkoxymercuration– demercuration and (2) the Williamson synthesis. (When one of these methods cannot be used for the given ether, point out why it will not work.)

(d) 1-methoxy-1-methylcyclopentane

views

Textbook Question

Show how you would use the Williamson ether synthesis to prepare the following ethers. You may use any alcohols or phenols as your organic starting materials.

(d) ethyl n-propyl ether (two ways)

(e) benzyl tert-butyl ether (benzyl = Ph–CH₂–)

views

Textbook Question

Give a common name (when possible) and a systematic name for each compound.

(d)

(e)

(f)

views

Textbook Question

Propose a fragmentation to account for each numbered peak in the mass spectrum of n-butyl isopropyl ether.

<IMAGE>