The major product which results when 2-chloro-2-methylpentane is heated in ethanol is an ether. What is the mechanism by which this ether forms?

1 Answer
Ernest Z.
May 20, 2015

The ether forms by an SN1 mechanism.

The overall reaction is

CH3CH2CH2C(CH3)2Cl+CH3CH2OH⇌CH3CH2CH2C(CH3)2(OCH2CH3)+HCl

The substrate is a 3° halide, and the ethanol is both a weak nucleophile and a polar protic solvent, so the reaction will go by an SN1 mechanism.

There will be no rearrangements, because the carbocation is already 3°.

THE MECHANISM

Step 1. Loss of Cl− to form a 3° carbocation.

CH3CH2CH2C(CH3)2Cl→CH3CH2CH2C(CH3)+2+Cl−

Step 2. Nucleophilic attack by ethanol

CH3CH2CH2C(CH3)+2+CH3CH2OH→CH3CH2CH2C(CH3)2-O+(H)CH2CH3

Step 3. Deprotonation of the oxonium ion

CH3CH2CH2C(CH3)2-+O(H)CH2CH3+CH3CH2-OH→CH3CH2CH2C(CH3)2-OCH2CH3+CH3CH2-OH+2

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