Download CHEMISTRY 212 EXAM 2 Friday, February 13, 2004 Answer Key 1

CHEMISTRY 212
EXAM 2
Friday, February 13, 2004
Answer Key
1. (12) State whether each of the following is aromatic or non-aromatic. In addition, give only the
following data which enabled you to arrive at your conclusion: fully conjugated - yes or no; # pi-electrons.
a)
b)
N
c)
N
O
N
aromatic; fully conjugated – yes
electrons
6 pi electrons
aromatic; fully conjugated – yes
non-aromatic; 6 pi
6 pi electrons
not fully conjugated
2. (7) In each example shown, circle the benzene ring most likely to react with an electrophile. You need not
explain your answer.
O
a)
b)
O2N
O
CH3
HN
3. (12) State whether each of the following molecules is activated or deactivated compared to benzene.
It is not necessary to explain why.
O
NH
a)
b)
activated
C
c)
CH 3
deactivated
O
activated
d)
OH
deactivated
4. (12) State whether further electrophilic substitution of each of the following molecules would occur in
the ortho / para or meta positions. It is not necessary to explain why.
O
O
H
a)
b)
c)
d)
S
N
Br
N
NH2
CH3
meta
ortho / para
ortho / para
meta
5. (8) Show the first step (complete) of the arrow-pushing mechanism for the reaction between each of
the following:
O
a)
OH
S
Cl
Cl
b)
6. (14) Synthesize the following starting from benzene or toluene. Show all steps and reagents.
Br
a)
NO2
1) Cl2 / FeCl3
2) HNO3 / H2 SO4 and
remove ortho
3) Br2 / FeBr 3
CH3
b)
Cl
COOH
1) CH3COCl / AlCl 3
2) remove ortho product
3) KMnO 4 / H2 O, heat
H3C
C
O
7. (3) One diagnostic feature in the NMR spectrum for alcohols is that on addition of D2O the signal
for the OH:
a) increases in strength
downfield
b) becomes a doublet
c) moves upfield
d) disappears
e) moves
8. (6) Classify the following reagents as oxidizing or reducing.
a)
KMnO4
oxidizing
b) PCC
oxidizing
c) NaBH4
reducing
9. (5) Draw a Grignard reagent and carbonyl compound that could be used to form the molecule shown:
OH
from
CH2
MgBr
and
O
10. (10) For the compound shown below, show all the resonance forms that illustrate the effect of the
group attached to the ring. In this case, you should show arrow-pushing to support your answer.
O
OH
O
OH
O
OH
O
OH
11. (4) Draw the carbonyl compound that could be reduced by NaBH4 to form the molecule shown:
OH
from
O
12. (32) Show reasonable products, or missing reactants, for the following reactions.
a)
H
OH
1) PhCH2
O
MgBr
2) H+
b)
O
1) LiAlH 4
OH
c)
OH
2) H+
OH
OH
CrO3, H2SO4
O
d)
H
PCC
OH
e)
O
H2SO4
+
cis
OH
Br
O
f)
Ph
H2
Ph
NBS
Ph
Pd
Ph
heat
Ph
Ph
13. (3) True or False? The molecule shown would react with NBS.
14. (3) True or False? In the Friedel-Crafts' alkylation shown, rearrangements would not be a problem.
+
Cl
AlCl3
15.
(3) Which one of the following compounds reacts most slowly with HNO3/H2SO4?
SO3 H
NH2
Cl
16. (4) Which of the following is the best method of preparing meta-nitrobenzoic acid from benzene?
a) CH3Cl with AlCl3; then KMnO4; then HNO3 / H2SO4
b) CH3Cl with AlCl3; then HNO3 / H2SO4; then KMnO4
c) HNO3 / H2SO4; then KMnO4; then CH3Cl with AlCl3
d) HNO3 / H2SO4; then CH3Cl with AlCl3; then KMnO4
17. (4) Which of the following sequences gives the compound shown at the left in the highest yield?
CO 2H
N O2
Br
a)
CO 2H
b)
CO 2 H
HN O3/H 2SO 4
Br2 /F eBr3
Br 2/FeBr 3
HN O3/H 2SO 4
c)
C H3
d)
C H3
Br 2 /FeBr 3
H NO 3/H2 SO 4
HNO 3/H2SO 4
Br 2/FeBr 3
KMnO 4 , 
KMnO 4, 
D would be the best choice
18.
(4) Which one of the following alcohols is oxidized to a ketone by Jones reagent?
CH3
OH
CH 2OH
OH
OH
19. (4) Which of the following reactions do not occur? More than one answer may be possible.
a. Benzene + Br2 in the presence of FeBr3; b. Nitrobenzene + 1-chlorobutane in the presence of AlCl3
c. PhCO2H + CH3COCl in the presence of AlCl3; d. Toluene + HNO3/H2SO4
Neither B nor C would occur