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The organic compounds containing two alkyl (or aryl) groups attached
to an oxygen atom are called ethers. They are the alkyl derivatives of
alcohols. They have the general formula R-O-R1.
Example: CH3 - O - CH3, dimethyl ether.
shown by Ethers
CH3 - O - CH2CH2CH2CH3
- O - CH2CH3
CH3 - O - CH2CH2CH3
CH3 - O - CH3
When sodium (or potassium) alkoxide is heated with an alkyl
halide, a corresponding ether is formed.
This reaction involves nucleophilic substitution of the halogen atom of
alkyl halide by the alkoxide group.
Williamson's synthesis is useful for the preparation of symmetrical and
unsymmetrical ethers. For the preparation of unsymmetrical ethers, a
primary alkyl halide is preferred. This is because, secondary and tertiary
alkyl halides on reacting with a sodium alkoxide form alkenes as a major
product instead of an ether.
continuous Etherification Process
When an alcohol is heated with a small quantity of concentrated
H2SO4 at a high temperature, a
corresponding ether is obtained.
This method is mainly used for dehydration of primary alcohols. As
secondary and tertiary alcohols give alkenes as their major product.
Dehydration of alcohols in the presence of a heated catalyst like alumina
(Al2O3) at about 525 K, also produce a corresponding ether.
This method is useful for preparing methyl ethers.
Alcohols react with diazomethane in the presence of fluoboric acid to
using Dry Silver Oxide:
When an alkyl halide is heated with dry silver oxide, a corresponding ether
of Hydriodic Acid (HI)
(i) With Simple Ethers:
With Mixed Ether:
With Mixed Ethers:
of Dilute H2SO4:
of Diethyl Ether