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CHEM 2312: Problem Set 1
Due on Wednesday, January 21, 2015, before class. Please provide your answers within the given
space, do not use separate or additional sheets.
Part I: Multistep Synthesis (15 points):
a) (9 points) Propose a three-step synthesis of compound M. Perform first a retrosynthetic analysis that
leads you to the indicated starting material cyclopentene. You should provide reagents and make sure
that you can perform each of the reactions in the synthetic pathway.
O
M
1. Step:
2. Step:
3. Step:
b) (3 points) How many stereoisomers of M exist?
c) (4 points) Draw the structure of the major stereoisomer(s) of M you would expect to be formed:
Part II: Problems related to topic 1 (30 points)
Please provide answers for all multiple choice questions on a Scantron card.
1. Select the structure(s) of the conjugated diene(s):
C
I
II
III
a. IV
d. I, III, and V
V
IV
b. I
e. I, II, and III
c. I and III
2. Arrange the following carbocations in the order of expected increasing stability:
I
II
a. IV < II < I < V < III
d. III < V < I < IV < II
III
V
IV
b. III < V < I < II < IV
e. II < IV < I < V < III
c. V < I < II < IV < III
3. Which hydrogen atom in the following compound is least susceptible towards abstraction by free
radicals?
I
IV
III
a. I
b. II
II
V
c. III
d. IV
e. V
d. 3
e. 4
4. Butadiene has how many electrons in π−bonding molecular orbital(s)?
a. 0
b. 1
c. 2
5. Which alkene would you expect to have the least exothermic heat of hydrogenation?
a.
b.
c.
d.
e.
6. Which of the following is not a proper resonance structure for 2,3-dimethyl-buta-1,3-diene?
a.
b.
c.
d.
e. all are correct
7. The diagram below describes the fate of intermediate K in a reversible reaction. Which of the
following conclusions is correct?
The less stable product forms more rapidly.
The more stable product forms more rapidly.
Product P2 will predominate at equilibrium.
The intermediate K has a short lifetime.
No conclusions can be drawn as to either reaction rate or
product stability.
potential energy
a.
b.
c.
d.
e.
K
P2
P1
reaction coordinate
8. Which diene and dienophile would you choose to synthesize compound Q?
Q
COOCH 3
COOCH 3
COOCH 3
a.
and
COOCH 3
b.
and
COOCH 3
COOCH 3
c.
and
e.
and
H 3COOC
COOCH 3
H 3COOC
d.
COOCH 3
and
COOCH 3
COOCH 3
9. Which of the following comounds is 4-bromo-2-nitroaniline?
Br
Br
NH 2
a.
Br
b.
NO 2
c.
NO 2
OCH3
Br
Br
H 3CO
d.
e.
H 2N
NH 2
NO 2
NO 2
NO 2
10. On the basis of molecular orbital theory and Hückelʼs rule, which of the following should be aromatic?
N
N
H
O
I
II
III
N
O
VI
a. IV, V, VII, X
d. V, VII, IX, X
VII
V
IV
VIII
b. II, IV, V, X
e. I, III, VI, VIII
IX
H
H
N
X
c. II, IV, V, VII, X
Part III: Review of CHEM 2311 (54 points):
11. Based on VSEPR theory, which of the following would not have a trigonal pyramidal shape?
a. SOCl2
b. BrF3
c. (H3C)2SO
d. PCl3
e. CH3
–
12. Which of the following molecules has not at least one sp hybridized atom?
a. I3
–
b. CO2
c. HCN
d. N2O
e. N3
–
13. Which of the following species is/are not a resonance form(s) of the species in the box?
SCH 3
a.
SCH 3
SCH 3
d.
SCH 3
b.
SCH 3
c.
e. more than two of these are incorrect
resonance forms
14. (2R,4S)-2,4–Dichloropentane and (2S,4R)-2,4-dichloropentane are:
a. enantiomers
b. diastereomers
e. conformational isomers
c. identical
d. constitutional isomers
15. Which staggered Newman projection(s), looking down the C-2—C-3 bond (C-2 in front and C-3 in
back), illustrates the following boxed compound?
H 3C
I
HO
OH
CH 3
H
H
IV
HO
a. I, II, and V
b. II and V
II
H
CH=CH2
HO
CH=CH2
H
H 3C
H
CH 3
CH 3
III
CH 3
V
H
CH=CH2
c. III and IV
H 3C
H
H
b. 2
c. 3
OH
CH=CH2
d. V
d. 4
OH
CH=CH2
CH 3
CH 3
e. none of these
16. How many alkanes of formula C7H16 possess a quaternary carbon atom?
a. 1
H
CH 3
H
e. 5
17. The drug Crixivan depcited below is an HIV protease inhibitor. Crixivan has how many stereogenic
centers?
N
OH
N
N
HN
a. 2
18.
c. 5
d. 6
e. 7
Which of the following molecules is a meso compound?
H
H
H
I
F
H
II
OH F
H
H
IV
III
F
a. I and II
19.
Crixivan
O
O
b. 4
OH
H
N
H
H
b. IV and V
F
H
c. II and III
d. I, II, and III
CH 3
F
CH 3
F
CH 3
V
CH 3
e. none of these
What are the correct stereochemical descriptors for (+)-camphor?
4
(+)-Camphor
1
O
a. 1R,4R
b. 1R,4S
c. 1S,4S
d. 1S,4R
e. the molecule is not chiral
20. Which of the following molecules are not chiral?
H 3C
CH 3
C
H
H
H
HO
HO
H
I
a. I and IV
CH 3
OH
H
H
OH
CH 3
II
b. IV and V
Cl
OH
H 3C
O
H
H
CH 3
III
c. II and IV
Ph
Ph
OH
Cl
IV
V
d. I, II, and IV
e. all of these are chiral
d. PF5
e. all of these are Lewis acids
21. Which of the following is not a Lewis acid?
a. SO3
b. TiCl4
c. CO
22. Which of the following compounds is not polar?
a.
b.
CO2
c. CO
PCl 3
d.
CHCl 3
e. tetrahydrofurane
23. Which of the following will likely not act as a nucleophile?
a.
H 2N
b.
H
Al
H
H
H
c.
N
d.
e. CH 3I
24. In the structure shown below, rank the hydrogen atoms from highest to lowest in acidity.
O
Hc
O
N
Ha
a) Ha>Hb>Hc>Hd
b) Ha>Hc>Hd>Hb
Hd
c) Hc>Hd>Ha>Hb
d) Hd>Ha>Hc>Hb
e) Hc>Ha>Hd>Hb
Hb
25. Which of these might be used as a protic solvent?
O
O
a.
OCH3
b.
c.
H 2N
d.
N
CHO
e.
O
26. What is the major product for the following reaction?
1. nBuLi, THF
N
H
a.
N
Bu
b.
N
Li
c.
?
2. D 2O
d.
N
D
D
N
H
e.
N
D
27. You want to synthesize 3-methyl-2-pentene from 2-chloro-3-methylpentane. Which reagent would you
use?
a. HCl, heat
d. EtONa, EtOH
b. NH3(aq)
e. CH3OH, heat
c. CH3CO2Na, CH3CO2H, heat
28. Which would be the best choice of reagents to accomplish the following transformation?
Br
a. HBr, peroxides
c. PBr3
e. NBS, H2O
b. HBr (no peroxides)
d. Br2 in CCl4