Ethers
R-O-R
or
R-O-R´
Nomenclature:
simple ethers are named:
“alkyl alkyl ether”
“dialkyl ether” if symmetric
CH3CH2-O-CH2CH3
diethyl ether
CH3 CH3
CH3CH-O-CHCH3
diisopropyl ether
CH3-O-C(CH3)3
tert-butyl methyl ether (MTBE)
If complex, the ether part is named as an “alkoxy” group:
CH3-O- = methoxy
CH3CH2-O- = ethoxy, etc.
CH3-O-CH2CH2CH2-O-CH3
1,3-dimethoxypropane
HO-CH2CH2-O-CH2CH3
2-ethoxyethanol
Physical properties:
R
: :
O
R'
oxygen is sp3 hybridized, bond angle ~ 109.5o
ethers are polar; no hydrogen bonding
mp/bp moderate
water insoluble
Diethyl ether = very important organic solvent, polar, water
insoluble, bp = 35o. Very flammable & forms explosive
peroxides.
Industrial synthesis for diethyl ether:
2 CH3CH2-OH + H2SO4, 140oC  CH3CH2-O-CH2CH3 + H2O
Not generally useful for syntheses of ethers in the lab:
a) Only symmetric ethers can be made this way.
b) Conditions are very compound specific
( at 180o ethanol would yield ethylene instead of the ether)
Synthesis of ethers
1. Williamson Synthesis.
R-O-Na+
+ R´-X

R´-X should be CH3 or 1o
SN2 mechanism
R-O-R´
+
NaX
Mechanism for the Williamson Synthesis = SN2
RDS
R O + R'
X
R´-X should be CH3 or 1o
R O R'
+
X
R-OH
+ Na 
R-O-Na+
 R-O-R´
R´-OH
+
HX
 R´-X
(CH3)2CH-OH + Na  (CH3)2CH-O-Na+
+
CH3CH2CH2-OH + HBr  CH3CH2CH2-Br
 CH3CH2CH2-O-CH(CH3)2
isopropyl n-propyl ether
note: the alkyl halide is primary! 
CH3CH2CH2-OH + Na  CH3CH2CH2-ONa
+
 CH3CH2CH2-O-CH(CH3)2
(CH3)2CH-OH + HBr  (CH3)2CH-Br
2o
 alkene
The product of this attempted Williamson Synthesis using a
secondary alkyl halide results not in the desired ether but in an
alkene!

The alkyl halide in a Williamson Synthesis must beCH3 or 1o!
Synthesis of di-tert-butyl ether?
CH3 CH3
CH3C-O-CCH3
CH3 CH3
Cannot be made via the Williamson
Synthesis. The alkyl halide would
be 3o.
2. Alkoxymercuration-demercuration
A way to make ethers that cannot be made via the Williamson
Synthesis. (later)
R-H
R-X
R-OH
Metals
NR
NR
NR
NR



 some


NR
NR
Oxid.
NR
NR

NR
Reduc.
NR

NR
NR
Halogens
NR
NR
NR
NR
Acids
Bases
R-O-R
Reactions, ethers:
1. Acid cleavage.
R-O-R´
+ (conc) HX, heat 
CH3CH2-O-CH2CH3
+
HBr, heat 
R-X
+ R´-X
2 CH3CH2-Br
Mechanism
1) CH3CH2 O CH2CH3 + HX
SN2
H
O CH2CH3
2)
X
3)
CH3CH2 OH + HX
+ CH3CH2
CH3CH2
CH3CH2 X + HO CH2CH3
CH3CH2 OH2
SN2
4)
CH3CH2 OH2 + X
H
O CH2CH3 + X
CH3CH2 X
+
X
+ H2O
Alkanes
Nomenclature
Syntheses
1.
2. reduction of an alkyl halide
a) hydrolysis of a Grignard reagent
b) with an active metal and acid
3. Corey-House Synthesis
Reactions
1. halogenation
2. combustion (oxidation)
3. pyrolysis (cracking)
Alkyl halides:
nomenclature
syntheses:
1. from alcohols
a) HX
b) PX3
2. halogenation of certain alkanes
3.
4.
5. halide exchange for iodide
reactions:
1. nucleophilic substitution
2.
3. formation of Grignard reagent
4. reduction
Alcohols:
nomenclature
syntheses
later
reactions
1. HX
2. PX3
3.
4. as acids
5. ester formation
6. oxidation
Ethers
nomenclature
syntheses
1. Williamson Synthesis
2.
reactions
1. acid cleavage
Mechanisms:
Free radical substitution
SN2
SN1
Memorize (all steps, curved arrow formalism, RDS) and know which
reactions go by these mechanisms!