Final Exam Key

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CHEMISTRY 212
FINAL EXAM
March 14, 2002
Answer Key
1. (2.5) True or False. Reactions between amides and nucleophiles are typically carried out in the
presence of an acid catalyst to speed up the reaction.
2. (3) True or False. The first step of the reaction between a Grignard and an acyl halide involves loss of
the halide.
3. (8) Draw structures for:
a) 3-bromo-2,3-dimethylhexanoic acid
O
Br
OH
b) 2-isopropoxy-3-phenylheptane
O
4. (6) Indicate which spectral technique, infrared spectroscopy or proton-NMR, would most readily
allow differentiation between the 2 compounds shown. Explain in each case why one method would be
unsatisfactory and what would allow distinction with the other.
a)
CH3
H3 C C Cl
CH3
ClCH2 CH
CH3
CH3
I.R. would not be useful since both
compounds have essentially the same
make-up: CH stretch & C-Cl stretch.
Both H-NMR and C-NMR would be useful. Thus, for the molecule on the left: in its H-NMR
spectrum, it would show a singlet at ~1.75  For the molecule on the right: in its H-NMR
spectrum, it would show a doublet at ~3.75, a nonet at ~2, and a doublet at ~1. The C-NMR
of the molecule on the left would be 2 peaks, 1 at ~40, the other at ~60. The C-NMR of
the molecule on the right would be 3 peaks, 1 at ~60, 1 at ~40, and 1 at ~20.
b)
O
O
O
O
O
H- or C-NMR would not be useful since both
compounds have essentially the same
make-up: 1 single peak at ~3.75  or ~70ppm,
respectively.
I.R. would be useful since the molecule on the right would have a distinct peak at ~1700 cm
the C=O stretch. The molecule on the left would not have this peak.
-1
for
5. (7.5) For the compound shown below, show all the resonance forms that illustrate the effect of the
group attached to the ring. Arrow-pushing is required.
H
N
H
N
H
N
H
N
6. (21) From the list given, choose the best reagent for each transformation shown. Write the
appropriate letter above the reaction arrow. It is possible to use the same reagent more than once.
A. EtMgBr then H3O+
B. Me2CuLi then H+ C. Zn / Hg /HCl
D. CrO3 / H2SO4
+
+
E. H2 / Pd
F. NaBH4 then H3O
G. MeOH / H
H. Et2NH / H+
I. NEt3 / Me3SiCl
J. PCC
K. NaNH2 then EtI
L. EtNH2 / H+
O
N
L
O
O
B
O
OH
A
O
OH
A
O
O
O
G
H O
O
O
D
H O
O
C
O
H O
7. (7) In each of the following, show one other satisfactory resonance form.
a)
O
O
b)
NH
NH
8. (9) Show the first step (complete) of the arrow-pushing mechanism for the reaction between each of
the following:
a)
(CH3)3Si-Cl
HOCH 2CH3
b)
BH3
O
O
c)
O
H
O
O
H
H
9. (28) Show reasonable products from the following reactions.
a)
OH
1) NaNH2
O
Ph
2) PhCH2 Br
b)
O
+
Ph
O
c)
H
N
Ph
OH
MgBr
H
d)
O
Ph
+
N
H+ cat.
HO
+
H+ cat.
O
Ph
O
e)
1) CH3 COCl / AlCl 3
2) HNO3 / H2SO4
3) H2 / Pd
f)
Ph
H2SO4
HO
g)
Et2CuLi
O
then H
Cl
+
NO2
Ph
Ph
+
O
10. (3) The reaction between an amine and an acid chloride is often carried out in aqueous sodium
hydroxide since:
a) the amine has an acidic proton which has to be removed prior to reaction
b) hydroxide reacts well with acid chlorides to form the more reactive carboxylic acids
c) HCl is also formed and this must be neutralized
d) acid chlorides are more unstable in organic solvents
e) bonding to the OH anion helps the Cl to leave
11. (3) If the position for an aldehyde C=O str. in the IR spectrum is 1715 cm-1 then an
-unsaturated ketone C=O str. would be about:
a) 1725 cm-1
b) 1685 cm-1
c) 1560 cm-1
d) 1740 cm-1
e) 1715 cm-1
12. (10) Circle all compounds below which are predicted to be aromatic, draw a large X through those
which are not aromatic.
O
X
O
N
N
X
N
H
13. (9) For each of the following compounds, state whether or not the benzene rings are activated or
deactivated in comparison with benzene itself. In addition, state whether each compound would be an
ortho / para or meta director. You need not explain your answers.
S
a)
N
activated; ortho / para
b)
PMe3
deactivated; meta
c)
OH
deactivated; meta
14. (4) The molecule shown may be prepared by a Diels-Alder reaction . Write the structures of the
diene and dienophile necessary to do so.
CO2 Et
EtO2C
H
+
H
CO2 Et
CO2 Et
15. (3) Circle the major product from the reaction shown below.
CH 3
CH 3CH2 C CH3
Br
NaOCH2CH3
;
;
;
16. (3) Circle the major product from the reaction shown below.
H
Br
H 3C
CH 3CH2
KOCH3
CH3
CH2 CH3
;
;
;
17. (3) How many signals are present in the proton NMR spectrum of the following molecule?
(CH3)2CHOCH2CH2OCH(CH3)2
a) 2
b) 3 c) 4 d) 5 e) 6
18. (3) Which of the following compounds has two signals in its carbon NMR spectrum?
a) CH3CH(OH)CH3
b) CH3CH2CH(Br)CH3 c) HOCH2CH2OH d) (CH3)2CHCH2OH
19. (3) What splitting pattern (singlet, doublet, etc.) is observed in the 1H-NMR spectrum for the
indicated hydrogen?
ClCH2CH2CH2CH2Cl
a) singlet
d) quartet
b) doublet
e) quintet
c) triplet
20. (8) For each of the following molecules, indicate the number of different types of hydrogen and the number of
different types of carbon present.
a)
O
1 type of H
1 type of C
2 types of H
3 types of C
b)
O
21. (3) A rounded, medium strength peak at ~3300 cm-1 in an IR spectrum would indicate?
A. A carboxylic acid
E. An alcohol
B. An amine
C. An aromatic ring
D. A cyclohexene
22. (3) Classify the following reagents as oxidizing or reducing.
a) PCC
oxidizing
b) KMnO4
oxidizing
c) NaBH4
reducing
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