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Chapter 14


Physical Properties of Ethers
o Fairly low boiling point because there is no hydrogen-bonding in pure ethers.
 Ethers can accept hydrogen bonds when in solution with hydrogenbonding compounds.
o Why ethers make good solvents
 Dissolve a wide range of solutes.
 Moderately polar
 Fairly nonreactive in a large variety of conditions
 Volatile (low-boiling): easily removed by evaporation
 Inexpensive
o Crown ethers
 Solvate specific cations based on the size of the cavity in the middle.
 Ex.
Nomenclature of ethers
o Common Names
 “alkyl alkyl ether”
 Name each alkyl piece separately, then say “ether”

o Ethyl isopropyl ether
“dialkyl ether” if it’s a symmetrical ether
o Diisopropyl ether
o IUPAC
 Name the smaller, less complex piece as “alkoxy”
 Ex. –OCH3 would be “methoxy”
 The ether has no priority.
OEt

 7-ethoxyoct-1-ene
To name epoxides, just say the number of the two carbons attached to
the oxygen, followed by “epoxy”
OH


7,8-epoxyoctan-2-ol
 Don’t worry about naming them as “oxiranes.”
Review of the Synthesis of Ethers
o Williamson Ether Synthesis – See Chapter 11 Notes
 Intramolecular Williamson Ether Syntheses
 Chemically, this is not any different, but sometimes it can be
difficult to figure out where substituents go on the product.
 To make this easy on yourself, number all the atoms!
7
-
8
2
3
1

6
4
5
Then, make your ring with the correct number of atoms
1
6
2
5
3
4

Now, add your substituents, making sure that they’re connected to the
same atoms as before.
1
7
2
6
5
3
4
8

o Alkoxymercuration-demercuration – See Chapter 8 Notes
o Industrial Synthesis of Symmetrical Ethers – See Chapter 11 Notes
Cleavage of Ethers of HBr and HI
o HCl doesn’t work because it isn’t acidic enough
o Step 1: Protonation of the oxygen to make a good leaving group (yawn)
H+
o Step 2: X- attacks in an SN1 or SN2 mechanism (SN1 is better so if you’re asked to
draw a mechanism of this, do the SN1 first if possible)


o Step 3: The resulting alcohol further reacts with the HBr or HI to give the
corresponding alkyl halide
 See Chapter 11 Notes for mechanism
Autoxidation of ethers
o Once ethers are exposed to oxygen, they can begin to slowly turn into peroxides.
o Peroxides are contact explosives, so if crystals get under the cap of a jar, when
you open the jar, it explodes.
o You don’t need to know more than that.
Sulfur-containing compounds
o You need to be able to draw and identify each of these types of compounds.
o If you just remember the names in this order, it’s easy because you add another
oxygen each time.
R
R
sulfide

R
R
R
R
R
R
R
R
sulfoxide
sulfone
sulfonate
Synthesis of epoxides
o Epoxidation of alkenes
 See Chapter 8 Notes
o Cyclization of Halohydrins
 Formation of halohydrins
 See Chapter 8 Notes
 Step 1: Hydroxide deprotonates the hydroxyl group
sulfate
-OH



This should look wrong because we’ve said before that you can’t
quantitatively deprotonate alcohols with hydroxide because it
isn’t strong enough.
 This action does go to completion, not because the base is so
strong, but because the next step is favorable.
o If you use the product of one step as a reagent in a
favorable subsequent step, you drive the equilibrium of
the first step forward. (LeChatelier just won’t leave us
alone!)
o This reaction is what made coupled reactions make sense
for me in biology, so maybe those of you who really like
biology will find that your understanding of coupled
reactions will make this make more sense.
Step 2: The negatively-charged oxygen kicks off the halogen in an
intramolecular SN2.
Ring opening of epoxides
o Acid-Catalyzed
 The nucleophile hits the more substituted side of the epoxide ring
 This is because the more substituted side has a larger partial
positive charge.
H+
CH3
CH3
CH3OH
o Base-Catalyzed
 The nucleophile hits the less substituted side of the epoxide ring.
 This is because of steric effects.
 This is true of all bases, not just hydroxide and alkoxides.
o There’s no point in treating Grignards and organolithiums
differently here because they’re just bases too!
 You will often see the conjugate acid of the base used as the
solvent.
o Don’t freak out!
o Use the strongest nucleophile present (the base)
H+
OCH3
CH3O-

Epoxy resins
o You don’t need to know anything about these, but they’re delightful (and
installing them as flooring in food-processing plants is a noble and glamorous
calling).
OCH3