Exam-III
November 16, 2010
BOO#
This exam is divided up into two parts, multiple choice and short answer questions. All work
must be shown in order to receive full credit. Please turn off all electronic communication
devices.
Multiple choice questions: Choose the correct answer and record it on the scantron provided.
/_
L-r" (2 points each)
1. What is the characteristic of a radical chain termination step?
(a). radicals are formed
(b). substitution products are formed as radicals
(c). a radical reaets with a molecule to give a new radical and a new molecule
(d). two radicals combine to give a molecule
2. The reaction of tert-butyl chloride, (CH3):CCI, with water in an inert solvent gives tert-butyl
alcohol, (CHI)ICOH. What is the effect of doubling thb concentration of water on the rate of
the reaction?
(b). the rate decreases by a factor of 2
(a). the rate remains the same
(d). the rate increases by a factor of 4
(c). the rate increases by a factor of 2
3. Which of the following energy diagrams represents the course of an exothermic SNI reaction?
(t
P
L
o
o
c
C
o
o
reaction
coordinate
4.
reaction
coordinate
reaction
reaction
coordinate
coordinate
Which of the following alkyl halides undergoes the fastest Sy2 reaction with sodium azide,
NaNg?
(a). l -fluorohexane
(c). 1-bromohexane
(b). l -chlorohexane
(d). 1-iodohexane
5. Which of the following solvents is the best choice for the reaction of l-chlorohexane with
sodium hydroxide?
(a). dimethyl sulfoxide
6.
(b).
water
(c). hexane
(d). Methanol
Which of the following statements is not lrue regarding the Sy2 reaction of (R)-2bromobutane with sodium cyanide?
(a). the reaction proceeds with inversion of configuration
(b). the rate is proportional to the concentration of sodium cyanide
(c). the rate is proportional to the concentration of (R)-2-bromobutane
(d). the rate of the reaction is independent of the identt'ty of the solvent
I
t
7.
What is the IUPAC name of the following compound?
"\.s
{(
-a"N
Hrc/
(a).
(c).
8.
(R)-4-methyl-2-hexyne (b). (S)-4-methyl-2-hexyne
(R)-3-methyl-4-hexyne (d). (^f)-3-methyl-4-hexyne
Which sequence of reactions can be used to convert 1-pentene to 1-pentyne
(a). Treatment with HBr; followed by treatment with NaOH
(b). Treatment with Brz; followed by treatment with KOH
(c). Treatment with Brz; followed by treatment with HzSOc
(d). Treatment with HzO; followed by treatment with NaOH
What is the major organic product obtained from the following reaction?
1. NaNH2
2. CH3CH2CH2BT
(a). 2-methyl-3 -hexene
O). 2-methyl-3 -heptyne
(c). 2-bromo-3-methylbutane' (d). 2-methyl-2-butene
10. What is the major organic product obtained from the following reaction?
ooH
I
ill
\,A--
/^\//
ab
cH3cH2c':cH
+
Hzo
HgSO+
H2soa
OH
OH
I
'//\-/
I
|
,OH
cl,.d\
11.
-/-A-\:.
What is the major organic product obtained from the following reaction?
/
/-/
-.
Hac..
\H2ab
cH-c-c-cHs #
-,/
Lindlar catalyst
HgC
2
\:/
/
---\
-r/
-/
\
12. What is the best choice of
-+
H3C-C_C-H
reagent(s) to perform the following transformation?
BrH
?
"ll ll
HaC-C
BrH
(b). 2 moles of Brz
(d). 2 moles of HBr
(a). 1 mole of Brz
(c). I mole of H
following sets consists of only polar protic solvents?
(b). acetic acid, methanol, water
(a). water, DMF, DMSO
(c). DMSO, ethanol, acetonitrile (d). DMF, acetonitrile, DMSO
13. Which of the
14. Which of the
followingbonds (circled) gives the weakest absorbance in the IR spectrum?
H.c-@cn.
ril
H.cAcH.
c
15. Which of the following compounds gives an infrared spectrum with apeak in the range of
(strong peaki, but does not have peaks at3200-3650 c*-'?
1700- 1725
"*-t
OH
I
l-
./\V
c
Short answer questions
1. How could you synthesize trans-3-octene starting from acetylene. Use any organic and
inorganic reagents and solvents as necessary (12',points).
,
-{ l0
H
acetylene
+
trans-3-octene
2. Five compounds
(1-5) and five IR spectra are shown below. Match each compound with the
coffesponding IR spectrum (15 points).
#
d*dry'Dw"'
-i
E
E
=
tsD
E
,O
E
B
F
2563 l3
2S35 2t
2€"5
2686
?67t
t?lo
t 459
26
62
53
4,,
.t4
0
llf,YEHUtlE EF I -r 1
100
-i
U
E
=
r50
E
{t
E
=
B
F
34 3,t
3092
3064
?0
?q
17
?o
3047
3920
't7
t934
E6
s25
s6
l9z0
ls94
88
t
1509
1494
4
7
tl
llflvEHUillER| -rI
4
-i
E
!sD
E
E
3088
3064
30 30
66
2900
a6
47
2A2E
r
E"
44
2SSO 12
z'724 E3
1954 8t
lg?E 6l
-t724 4
1602 s2
l5E5 'tE
lE4S 8E
500
-{
E
3342 lE
2929 .4
2A5E lO
2686 64
1693 84
t 461 2l
1448 26
E50
r
D
llSlvEHUhSEF|
-rI
t0D
3106 t6
3291 tZ
30sI
E
3058
62
82
=
Es0
30
6E
1022
12
?4
84
-{
E
E
-r
v,
E
F
34
zu.o
l9s4
ls00
l8s6
1808
I?5?
gE
84
gE
6E
lEss lD
1674 68
t488 15
t444 3l
llf,vEllUlllEF| -tI
5
3.
t4
What are the products formed in the following allylic bromination reaction? Draw the
mechanism for the formation of the products (13 points).
NBS, light
ccl4
,,
II/ t 4. The compound below has a chiral center (16 points).
lo
.\rWhat is the absolute configuration of the chiral center?
(a)
'v
(b) Predict the product resulting from the SN2 reaction of this halide with the nucleophile,
CH:S-in DMF.
(c) What is the absolute configuration of the product formed?
(d Expalin the reasons for the observed stereochemical outcome of the reaction.
H:Q
cH3sDMF
Hrc
'i'
\ \il
+\\
5.
Give the structure ofthe principal organic product(s) in the following reactions indicating
both regiochemistry and stereochemistry when appropriate (14 points)?
(a) Hrcf
t. BH3
\_
2. NaOH,HzOz
(b)
cHr
Hgc
H2
Lindlar catalyst
HBr
................................*
(c)
peroxides
+ HCI
(d)
ether
OH
(e)
W
SOCIr
I
pyridine
-->
(0
N
+ PBrr
I
ether
I
OH
Hrc
CHr
Br2 excess
cHCl3
8