Further Reactions of Alcohols and the Chemistry of Ethers | Organic Chemistry 1
Typical Reactions of Alcohols
Deprotonation of Alcohols
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+.
Substitution of Alcohols
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:
Carbocation Rearrangements - SN Reactions
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:
Carbocation Rearrangements - E Reactions
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 Synthesis
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
Reactivity of Epoxides
Mechanism of acid catalyzed ring opening: