Further Reactions of Alcohols and the Chemistry of Ethers | Organic Chemistry 1

Strong bases are needed to deprotonate alcohols.
Common strong bases: LDA, Butyl Lithium (BuLi), Potassium Hydride (KH).

 Alkali metals can also deprotonate alcohols by reduction of H⁺.

One of the typical reactions of alcohols is the substitution of HO^- by another chemical group.
This can lead to the synthesis of alkyl halides:
 

However, HO^- is a bad leaving group.
We must modify it to favor SN reactions.

- Mesyl Chloride CH₃SO₂Cl as a good leaving group:

 

- Water as a good leaving group:

Rearrangement of the secondary carbocation into the more stable tertiary one.
The rearrangement is only observed during a SN1 reaction.
2 rearrangements are possible: hydride shift or alkyl shift.
 

- Hydride shift:

- Alkyl shift:

The more substituted alkenes are preferred.
The rearrangement is only observed during a E1 reaction.
2 rearrangements are possible: hydride shift or alkyl shift.
 

- Hydride shift (same process with alkyl shift):

Ether chemical function: R-O-R'.
Different synthesis methods depending on the desired ether (linear, cyclic or epoxide):

- Intramolecular SN reaction for linear and cyclic ethers

 - Williamson Synthesis for epoxides

Mechanism of acid catalyzed ring opening: