Sample Exam 4
Name __________________________
CHEM 210
1.
(48 pts) Complete the equations for the following reactions. Show all organic products – if two or more products form,
indicate the major product. Indicate proper stereochemistry where necessary.
a.
b.
c.
H 2O, H 2SO 4
d.
e.
f.
H2
Pt/C
g.
H2
Pd/CaCO 3
quinoline
h.
OsO4, NMO
i.
KMnO 4
KOH, H 2O, Δ
j.
NBS, peroxide
Δ
k.
NBS, hν
l.
Cl2
hν, 120 oC
2. (12 pts) Retrosynthesis
a.
from alkyne
b.
from alkene
c.
H
H
O
O
from alkene
3. (8 pts) Mechanism – Addition of Br2 to cyclohexene. Be sure to indicate any relevant stereochemistry!
Br 2
4. (8 pts) Mechanism – Addition of H2O to cyclohexene. Be sure to indicate any relevant stereochemistry!
H 2O
H 2SO 4
5. (5 pts) When the following cyclic ether is treated with methanol and a catalytic amount of H2SO4, one of the two
products shown is formed quantitatively with only a trace of the other. Which one is the major product? Propose a
reaction mechanism to illustrate why.
OCH3
CH3OH, H2SO 4
O
6.
+
O
OCH3
O
(5 pts) You have learned that symmetrical dihalides (X2, X=Cl, Br) add to alkenes to form vicinal dihalides.
Unsymmetrical dihalides such as iodine monochloride (ICl) also add to alkenes. For the following addition reaction of
ICl to styrene only one of the two indicated products is formed. Please indicate which one and briefly state why.
Score: ______/100
Projected Course Grade: _____
Sample Exam 4
Name _________KEY_______
CHEM 210
7.
(48 pts) Complete the equations for the following reactions. Show all organic products – if two or more products form,
indicate the major product. Indicate proper stereochemistry where necessary.
a.
OH
b.
O
c.
OH
H 2O, H 2SO 4
d.
Br
Br
Br
+
Br
e.
I
f.
H2
Pt/C
g.
H2
Pd/CaCO 3
quinoline
h.
OH
OsO4, NMO
OH
meso
i.
KMnO 4
HO
KOH, H 2O, Δ
OH
O
O
Br
j.
NBS, peroxide
Δ
k.
NBS, hν
Br
l.
Cl
Cl2
hν, 120 oC
Cl
Cl
Cl
major
8. (12 pts) Retrosynthesis
a.
Na, NH 3
from alkyne
CH2I 2/Zn(Cu)
from alkene
b.
c.
H
1) O3, -78 C
2) Me 2S
H
O
from alkene
O
9. (8 pts) Mechanism – Addition of Br2 to cyclohexene. Be sure to indicate any relevant stereochemistry!
Br 2
δ+
Br
δ−
Br
Br
Br
Br
Br
trans
10. (8 pts) Mechanism – Addition of H2O to cyclohexene. Be sure to indicate any relevant stereochemistry!
H 2O
H 2SO 4
H
H
O H
OH2
-H +
H
H
H
or
O H
H
O H
11. (5 pts) When the following cyclic ether is treated with methanol and a catalytic amount of H2SO4, one of the two
products shown is formed quantitatively with only a trace of the other. Which one is the major product? Propose a
reaction mechanism to illustrate why.
OCH3
CH3OH, H2SO 4
O
+
O
OCH3
O
o
The product on the left is the major one. Both carbocations are 2 , but the one that leads to the major product is
resonance stabilized by the lone pairs on the ether oxygen.
H
H
O
O
12. (5 pts) You have learned that symmetrical dihalides (X2, X=Cl, Br) add to alkenes to form vicinal dihalides.
Unsymmetrical dihalides such as iodine monochloride (ICl) also add to alkenes. For the following addition reaction of
ICl to styrene only one of the two indicated products is formed. Please indicate which one and briefly state why.
Chlorine is more electronegative than iodine. Therefore iodine would bear the partial positive charge in the mechanism
and add first. The cyclic iodonium ion would be broken by the chloride at the site that best handles positive charge – the
secondary site. So the product on the right is preferred.
δ+
δ−
I Cl
I
Cl
Score: ______/100
Projected Course Grade: _____