Ethers are organic compounds with functional group R-O-R

1. ETHERS
CHEMISTRY XII FDC
SIDRA JAVED
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2. NOMENCLATURE
COMMON SYSTEM OF NAMING:
◦ In common system of naming ethers (simple and mixed), ethers
are named by naming the two groups bonded to oxygen followed
by the word ether. For example:
◦ CH3-O-CH3 Dimethyl ether
◦ C2H5-O-CH3 Ethyl methyl ether
◦ C2H5-O-C2H5 Diethyl ether
◦ C6H5-O-CH3 Phenyl methyl ether
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3. NOMENCLATURE
IUPAC SYSTEM OF NAMING:
◦ In IUPAC system, large alkyl group is take as parent molecule and
given the last name (suffix) while the smaller alky group along with
oxygen is used as a prefix and given the name ALKOXY (e.g
methoxy, ethoxy, propoxy etc)
◦ CH3-O-CH3 Methoxy methane
◦ C2H5-O-CH3 Methoxy ethane
◦ C2H5-O-C2H5 Ethoxy ethane
◦ C6H5-O-CH3 Methoxy benzene
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4. PREPARATION OF ETHERS
1. WILLIAMSON’S SYNTHESIS (CONVERSION OF ALCOHOLS INTO ETHERS)
The reaction of primary alcohol with sodium gives an alkoxide
2CH3CH2OH + 2Na  2CH3CH2O-Na+
Alkoxide when treated with RCl forms ether
CH3CH2O-Na+ + CH3CH2Cl  CH3CH2-O-CH3CH2 + NaCl
2. REACTION OF ALKYL HALIDE WITH DRY SILVER OXIDE
when alkyl halides are heated with dry silver oxide, ethers are produced.
2C2H5Br + Ag2O  C2H5-O-C2H5 + 2AgBr
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5. PREPARATION OF ETHERS
3. DEHYDRATION OF ALCOHOLS
Ethers can be prepared by heating excess of alcohol with conc. H2SO4 at 140oC
2CH3CH2OH
𝐶𝑜𝑛𝑐.𝐻2 𝑆𝑂4 140 𝑜 𝐶
CH3CH2-O-CH3CH2 + H2O
When alcohols are of different types, then mixed ethers can be prepared.
CH3OH + CH3CH2OH
𝐶𝑜𝑛𝑐.𝐻2 𝑆𝑂4 140 𝑜 𝐶
CH3-O-CH3CH2 +CH3-O-CH3 +
CH3CH2-O-CH3CH2 + H2O
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6. PHYSICAL PROPERTIES OF ETHERS
1. Ethers are colorless, highly inflammable compounds of low boiling points
2. Their chemical inactivity and their ability to dissolve fats, oil, gums and many
more other organic compound make them very good solvent
3. Ethers are soluble in conc. sulfuric acid. This property is used as a
distinguishing test between ethers and saturated hydrocarbons.
4. Lower ethers act as anesthetics
5. Ethers are lighter than water
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7. CHEMICAL REACTIVITY OF ETHERS
The ethereal O atom is a region of high electron density due to lone pairs
Ether O atom are Lewis bases
Like an alcohol –OH group, the –OR group is a poor leaving group and needs to
be converted to a better leaving group before substitution can occur.
The most important reaction of ether is cleavage by acids such as HI and HBr
Resistance to Oxidations:
Ethers are resistant to attack by the usual chemical oxidizing agent. Reagents like
NH3, Na, alkali and acids have no action on ethers
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8. REACTION OF ETHER WITH HI AND HBr
Reaction with HBr:
The O atom of ether possess an unshared electron pair which accepts a proton
from HBr to form Oxonium ion. No further reaction takes place.
R2O + HBr  R2O+ -H + Br-
Reaction with HI:
The O atom of ether accepts a proton from HI to form oxonium ion, which reacts
with I- to form R-OH and RI
R2O + HI  R2O+-H + + I-
R2O+-H + + I-  R-OH + RI
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9. THE END
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