Further Reactions of Alcohols and the Chemistry of Ethers | Organic Chemistry 1
Typical Reactions of Alcohols
Deprotonation of Alcohols
pKa of alcohols ~ 16-18 ⇒ 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 and can be replaced with a better leaving group to favor SN reactions
Mesyl Chloride CH3SO2Cl as a better leaving group:
Water as a better leaving group:
Carbocation Rearrangements - SN Reactions
During a SN1 reaction, a rearrangement of the secondary carbocation into a more stable tertiary can be observed. 2 rearrangements are possible: hydride shift or alkyl shift
Hydride shift:
Alkyl (CH3) shift:
Carbocation Rearrangements - E Reactions
During an E1 reaction, a rearrangement of the carbocation can be observed to favor the Zaitsev product (the most substituted alkene). 2 rearrangements are possible: hydride shift or alkyl shift
Hydride shift:
Same process with an alkyl shift
Ether Synthesis
Ether:
Class of organic compounds that contain an oxygen atom connected to two alkyl or aryl groups
Epoxide: cyclic ether with a three-atom ring
Synthesis:
Linear and cyclic ethers by intramolecular SN reactions:
Epoxides by Williamson synthesis:
Reactivity of Epoxides
Mechanism of acid catalyzed ring opening:
