Ethers are organic compounds with an oxygen atom bonded to two alkyl or aryl groups. They can be symmetrical, with identical groups bonded to oxygen, or unsymmetrical. Ethers are named based on the groups attached to oxygen. Common methods for preparing ethers include the dehydration of alcohols and Williamson's synthesis using alkoxides and alkyl halides. Ethers have low boiling points, are inflammable, and act as good solvents. The C-O bond is stable but can react with acids or undergo halogenation.

2. ETHERS
ORGANIC CHEMISTRY -I
CHM- 260
BS CHEMISTRY
BY
DR. ASMA HANIF

3. Table of Contents
■ What are Ethers?
■ Nomenclature
■ Preparation of Ethers
■ Physical Properties
■ Reaction of Ethers

4. Ethers
■ Ethers are compounds having two alkyl or aryl groups bonded to an
oxygen atom.
R1–O–R2
■ Such linkage R1–O–R2 is called ether linkage.

5. Symmetrical and unsymmetrical ethers
Ethers are generally classified into two categories on the basis of substituent group
attached:
⮚ A symmetrical ether is an ether in the molecule of which the two ligands on
the ether group are identical.
CH3-CH2-O-CH2-CH3
⮚ An unsymmetrical ether is an ether in the molecule of which the two ligands on
the ether group are different.
CH3-CH2-O-CH3

6. Nomenclature of ethers
Common names:
■ By naming the two alkyl groups attached to the oxygen atoms ,in alphabetical order, followed by
the word ether.
■ If the groups are same, prefix di- is used with the group.
CH3-CH2-O-CH3 is called ethyl methyl ether or methoxyethane.
The smaller, shorter alkyl group becomes the alkoxy substituent. The larger,
longer alkyl group side becomes the alkane base name.
CH3-CH2-O-CH2-CH3
diethyl ether (sometimes referred to as just ether)
Example 1
Example 2

7. IUPAC system:
⮚ Ethers are named as Alkoxy alkanes.
Or
Compounds containing a functional group of higher priority than ether.
1-Methoxypropane Methoxycyclohexa
ne

8. Preparation of Ethers
■ Dehydration of alcohols
■ Williamson’s synthesis

9. Dehydration of alcohols
■ Symmetrical ethers are prepared by heating an excess of alcohol with conc.H2SO4
at 140 °C.
■ Dehydration of an alcohol to an alkene take place at a higher T than the
dehydration to an ether.

10. ■ This method is useful only for the preparation of symmetrical ethers.
■ This reaction cannot be employed to prepare unsymmetrical ethers. It is
because a mixture of products is likely to be obtained.
■ Formation of ether probably involves an SN2 mechanism in which one
molecule of the alcohol in protonated form act as the substrate, and the
other molecule (unprotonated) functions as the nucleophile.

12. Williamson’s synthesis
■ A very versatile and useful method for synthesizing symmetrical as well as unsymmetrical ethers.
■ The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and a
deprotonated alcohol (alkoxide).
■ This reaction was developed by Alexander Williamson in 1850. Typically it involves the reaction of an
alkoxide ion with a primary alkyl halide via an SN2 reaction.

13. Mechanism
The Williamson ether synthesis
is an SN2 reaction in which an
alkoxide ion is a nucleophile
that displaces a halide ion from
an alkyl halide to give an ether.
The leaving site must be a primary carbon, because secondary
and tertiary leaving sites generally prefer to proceed as
an elimination reaction.

14. Limitations
■ Tertiary alkyl halides or sterically hindered primary or secondary alkyl halides
tend to undergo E2 elimination in the presence of the alkoxide that in addition
to being a nucleophile also act as a base.
■ This process for preparing ethers is too limited to be of any practical value for
synthetic organic chemists.

15. Properties of Ether
1. Ethers are colorless, highly inflammable compounds of low boiling points.
1. Their chemical inactivity and their ability to dissolve fats, oil, gums and
many more other organic compound make them very good solvent.
1. Ethers are soluble in conc. sulfuric acid. This property is used as a
distinguishing test between ethers and saturated hydrocarbons.
1. Ethers are lighter than water.

16. Reactions of ethers
■ The ethereal O atom is a region of high electron density due to lone pairs.
■ The -OR group is a poor leaving group.
■ Ethers are quite stable compounds.
■ C-O bond does not cleave readily.
■ Used as solvents

17. Reaction with halogen acids

18. Mechanism

19. Halogenation

20. References
■ J. Mcmurry. 2000. Organic Chemistry. 5th Ed. Thomson Asia Ltd; Singapore.
■ W.H. Brown, C.S. Fotte, B.L. Inversion And E.V. Fryhle. 2012. Organic
Chemistry. 10th Ed. John Willey And Sons, Inc.