Key

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Practice Exam-III
Key -
Name
(Last)
BOO#
'
{a5iaYlO
(First)
_
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
(2 points each).
1. Which of the following compounds gives a carbonyl bond absorption at the highest
frequency?
o
(d)
2. Which of the following is the best set of conditions for the preparation of tert-butyl methyl
ether?
a)
tert-butyl fluoride and NaOCH3 in CH30H
(b) methang] and sodium tert-butoxide in tert-butanol
c) ~methane
and sodium tert-butoxide in tert-butanol
~
@ tert-butyl bromide and CH30H
5N)...
f(J('
~
/{!Jab,,][tl1Jt7
r. ]
:J
K L1. J).,]
~ .1 K
3. The reaction of methyl iodide with sodium azide, NaN3, proceeds by an SN2 mechanism·I'Clfc=
What is the effect of doubling the concentration of Nabl, on the rate of the reaction?
f.e(a) the rate remains the same
(b) the rate decreases by a factor of2
('(); (§) the rate increases by a factor of 2
(d) the rate increases by a factor of 4
!'ale
4. What is the equation for the rate of formation of tert-butyl alcohol from the reaction of tertbutyl bromide (t-BuBr) with water by an SN1 mechanism?
@Rate = k [t-BuBr]
(b) Rate = k [t-BuBr]DH20]
(c) Rate = k [H20]
(d) Rate = k [t-BuBr]~
5. Which
(a) the
(b) the
(c) the
the
@
of the following is not a characteristic of SN2 reactions?
electrophilic carbon undergoes inversion of stereochemistry
rate is proportional to the concentration of substrate v
rate is proportional to the concentration of nucleophile Y
rate is independent of the solvent
V
rate ~ )) ., K'r,;: , ·.I[
1
L?N7
- L5uPfimft.J
J
]
nu ~
.
carj;()-CIt/tfJll
6. Which of the following is most likely to undergo rearrangement
methanol?
during reaction with
7.J:m:~~~~~:~~J:d
X:lo;;:n~B'
N6,,- tfiJl.t"/{;{lAI/(,y-
(a)
@ Br
Br (b)
(d)
8. What is the ~dij&tftr~duct formed upon treatment of (R) 2-bromohexane
cyanide by SN2 mechanism?
W (R) 2-cyanohexane l'd~1II-Iw?~ (5) 2-cyanohexane/'nveI"$NI"/
(b).1-hexene ejlmln,.H~
~ 2-hexene e/l',n-Jrz4~
with sodium
. 8Vv
a/
9. In which of the following solvents would the reaction of l-bromobutane
NaN3, proceed the fastest?
(a) CH3COOH
(b) CH3CH20H
(c) H20
rITe
t""He.
I;t(}Hc
10. Which of the following is the most nucleophilic?
(§) sodiu~, ethoxide C/wy-c
(b) acetic
€¥V
-',O(H1CH3
~f
eN
•.
J
with sodium azide,
[of)
C#}
i1I6f JI1fIr/
'()H
(d) water
(c) methanol
I'lu:
OH
I~~
11. Which of the following energy diagrams represents the course of an exothermic El reaction?
t;)
,/
/uJ _
~
.~
&? \
rB r.g rft, rF
reaction
coordinate
reaction
coordinate
reaction
coordinate
f~ .>k/
reaction
coordinate
12. Which of the following processes takes place upon absorption of infrared radiation?
@ bond vibration (b) electron excitation
(c) nuclear spin flip (d) electron spin flip
13. Which of the following bonds gives rise to a strong, broad, absorbance at approximately
3200-3650 cm-1 in the infrared spectrum?
)a(C=O
@O-H
~C=C
;arC-H
/\. / fr!O
-1715
A/t?f- }~
14. Which of the following compounds gives an infrared spectrum with peaks at 3300 cm-1
(sharp peak) and 2150 cm-1 (sharp peak)?
~p l.
f
C£C
H
//C'-...,
CH3CH2C==CH
>,P - Hr"t''!~t1
Alb
~f-H yd~ftfJ
f5YJ1lrtJeft','C4{ trtrre
v:
~CH2
H2C"")Cl ~
@!
7rr~'II4(
Hc=cH
2
I
I
~/1la(
H-C Sf
H2C~r2
I
~PndfVllft(Jlecu/evfl/l
rcqd,'t1j at' J.J5"()cm'" (
15. Which of the following compounds gives an infrared spectrum with peaks at 3000-3500 em-I
and ~1720 em-I?
Jbr
17/~
Short answer questions.
1. Propose a mechanism for the formation of these products in the solvolysis of this
bromoalkane (12 points).
+
H~
.
. . 0 ,t- ·PT.
3
+
HBr
2.
l-Chloro-2-butene undergoes hydrolysis in warm water to give a mixture of these allylic
alcohols. Propose a mechanism for their formation (12 points).
r
~Cl
OH
.f~I
H20
.fDIM- I'fYJh'c
l-Chloro-2-butene
+
~OH
2-butene-l-ol
[H3
I
~
/J/
f//l-.qH ~ H-LZ/
CH:J
4
N
3-butene- 2-01
4. How would you use IR spectroscopy to determine if this reaction went to completion (10
points)?
d~H
A stroll! ,br'Uad
,rc~c.e
~f
A
C4V5(JrpHOf}
frf)q1
'J5rY()- 3Jf)Ocl11-r
aYJ a/{'tJh~/. Thl.r Wtmfd
/1j,f
W
fC~/J
~kld
I~
fhe
inti/calc the
de~/~c/
abfJve 5(JiJtJCM-t w~uld Ilut/cafe C{J1
5pl [-H pfltIj ,11 fhltnduc~ and a rwtdfIJ aTfJUtld "-/flte", wouLd
l~d,'Clttc lit (-c. ~ph ~.f f-he5e rY;ltdfrtf~ wbttld bR SUn ,'f f-he «Ciellen
w~n+- +0 Q;m~leHorl.
!fOdtuf:
re~d/Ilf
f/lfhrl),
~I
5. Show the stereochemistry (R and S) of the two stereoisomeric products formed in the
following SN 1reaction. Indicate which the major product is and explain why that is the case?
(12 points).
6. MATCH a structure from the list below to the following IR spectra. Place the letter of the
structure in the blank to the left of the spectrum (12 points).
~
C()
0
I
~
0
II
III
()OH
HOxy
H
0
0
IV
V
VI
LOO
VI
/'
50
sp! C··-H-
P\2?~P
>
I~O
.
c'Z.c
. '.~B'SO p"'t'r ~K>
(lUt!
.
L
S'r}C-q
rthJ
fo C-H.
in '" dt 11,;)(
t-rn9P!/l'tlvr
I
h1
/7:J.b .
0
~uoo
3000
2000
HAVENunB EflI-11
LOO
·
T
50
•..
MAl'ENUMD EFi!I-11
[continued
in next page
]
6
".
1000
'"0
(fMIC
100
fOOIl
•••••••
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.•
7
15DQ
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