Chapter 11 Notes

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Unformatted text preview: thesis
of
tert‐butyl
ethyl
ether
starting
with
compounds
of
four
 carbons
or
fewer.

You
may
use
any
reagents
in
the
transformation.
 Reactions
of
Ethers
 Acyclic
ethers
are
generally
unreactive,
except
for
cleavage
by
very
strong
acids
to
 form
the
corresponding
alkyl
halides.

Dialkyl
ethers
undergo
sequential
SN2
reactions
 with
HBr
to
form
2
equivalents
of
the
alkyl
bromide.
 Epoxides
 Epoxides
are
three‐membered
ring
cyclic
ethers.

These
groups
are
also
called
 oxiranes.
 Epoxides
are
usually
formed
by
reaction
of
alkenes
with
peroxy
acids.

This
process
is
 called
epoxidation
and
involves
syn
addition
of
oxygen.
 Magnesium
monoperoxyphthalate
(MMPP)
is
a
common
and
safe
peroxy
acid
for
 epoxidation.

 Epoxidation
is
stereospecfic:
Epoxidation
of
cis‐2‐butene
gives
the
meso
cis
oxirane.

 Epoxidation
of
trans‐2‐butene
gives
the
racemic
trans
oxirane.
 Reaction
of
Epoxides
 Epoxides
are
considerably
more
reactive
than
regular
ethers.

The
three‐membered
 ring
is
highly
strained
and
therefore
very
reactive.

Acid‐catalyzed
opening
of
an
 epoxide
occurs
by
initial
protonation
of
the
epoxide
oxygen,
making
the
epoxide
even
 more
reactive.

Acid‐catalyzed
hydrolysis
of
an
epoxide
leads
to
a
1,2‐diol.
 In
unsymmetrical
epoxides,
the
acid
catalyzed
ring...
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This note was uploaded on 06/19/2009 for the course CHEM 2311 taught by Professor Tyson during the Fall '07 term at Georgia Institute of Technology.

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