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transcript
cook.chem.ndsu.nodak.edu/chem341
©2012 Gregory R Cook
Chapter 06Addition Reactions of Alkenes
part 02
CHEM 341: Spring 2012
Prof. Greg Cook
cook.chem.ndsu.nodak.edu/chem341
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©2012 Gregory R Cook
• Le Chatlier’s principle
Addition-Elimination Equilibria
2
H2OH+ catalyst
+C C C COHH
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©2012 Gregory R Cook
H+ catalyst OHOHnot
R2B H
HBR2
OH-H2O2
Anti-Markovnikov Selectivity?
3
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©2012 Gregory R Cook
H
syn addition
HOH
H3C
H2O2 / NaOHH
BR2
anti-Markovnikovhydration
H
H BR2
H3C
H2O2 / NaOH
H
H OH
H3C
BR2H
Hydroboration/Oxidation Stereochemistry
4
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©2012 Gregory R Cook
Hydroboration Borohydride Sources
5
BH3•THF
B OH
HH
B2H6 in diglyme
BH
BH
H
H H
H
OO
O
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Mechanism of Hydroboration
6
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©2012 Gregory R Cook
Mechanism of Hydroboration
7
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©2012 Gregory R Cook
Halogenation of Alkenes
8
+C C C CX
XX X
+ Br BrBr
BrCHCl3
anti addition
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©2012 Gregory R Cook
Mechanism of Electrophilic Halogenation
9
Br Br
Br
Br
Br
Br
A bromonium ion
H
OH
O
Br
H
HOH
Br
-H+
a halohydrin
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©2012 Gregory R Cook
Regioselectivity of Halohydrin Formation
10
OH
OHnot
Br2H2O
Br
Br
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©2012 Gregory R Cook
Generalities of Electrophilic Addition
11
A+ B-
A
orA
A
B
A+ B-overall equivalent
reagents notes
HX H+ X- MarkovnikovX2 X+ X- bridged, anti addnX2/H2O X+ HO- bridged, anti addn, Markovnikov
H2O (H+ cat) H+ HO- MarkovnikovBH3 OH+ H- syn addn, anti-Markovnikovthen H2O2/OH-
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©2012 Gregory R Cook
Free Radical addition of HX - anti-Markovnikov
12
anti-Markovnikov
HBr
Br
H
90% yield
HBr
H
Br
95% yield
peroxides
Markovnikov
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©2012 Gregory R Cook
Free Radical addition of HX - Mechanism
13
anti-Markovnikov
HBr
Br
H
90% yield
HBr
H
Br
95% yield
peroxides
Markovnikov
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©2012 Gregory R Cook
Epoxides
14
water
HO
H RO
H RO
Ralcohol ether
C C
O
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©2012 Gregory R Cook
Expoxidation of Alkenes
15
peroxy acid
C C
O
+C C R O
OO
H
epoxide
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©2012 Gregory R Cook
Ozonolysis of Alkenes
16
ozone
OO
O
O3then Zn/HOAc
OO
+
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©2012 Gregory R Cook
Ozonolysis of Alkenes
17
O3then Zn/HOAc
OO
+
ozonide
O O
OO O
O
Zn/HOAc
O O
O
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©2012 Gregory R Cook
Multistep Synthesis Strategies
18
H H
OO? How would you prepare 1,5-pentandialdehyde starting from cyclopentane?
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Reactions of Alkenes with Alkenes - Polymers
19
monomer
265% H2SO4
+
dimer dimer
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©2012 Gregory R Cook
Polyethylene
20
polymerization
polyethylene
polymerization
polystyrene
Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph
Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph
Ph =
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