PRACTICE QUESTIONS FOR FINAL EXAM — CEM 252 SUMMER...PRACTICE QUESTIONS FOR FINAL EXAM — CEM 252...
Transcript of PRACTICE QUESTIONS FOR FINAL EXAM — CEM 252 SUMMER...PRACTICE QUESTIONS FOR FINAL EXAM — CEM 252...
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PRACTICE QUESTIONS FOR FINAL EXAM — CEM 252 SUMMER
1. (25 pts) Simple syntheses: In the boxes provided, draw the major organic products for each
of the following reactions (5 pts each).
OH 1) H2SO4/
Na2Cr2O72) Zn(Hg)/HCl
i.
OH
ii.
iii.
iv.
O
OH 1) SOCl22) Et2CuLi3) H3O+
v.
O
NH2
NaBH3CN
Acetic acid
O O
Opyridine
CH3COCl/AlCl3NH
O
Gord o
aEI EITEL
demyeenasey Pandit 5
iii ex EeoIHn.EeEIi so.IS
e imine 3pt amine
Etjn
Ior EEIII
Tea T.IEIterate00 toEst't off't't
T 9
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2. (35 pts) Reactions and mechanisms of amines:
(a) (5 pts) In the box, draw the intermediate in this two-step amine synthesis:
(b) (6 pts) In the boxes, draw simple examples of the requested compound types:
(c) (24 pts) Draw the intermediates (3 pt each) in the dotted boxes below and add arrows to show the mechanism for the imine-forming reaction of cyclohexanone with ethylamine. Be sure to include arrows (1 pt each) to move electrons. Ethylamine is the nucleophilic reagent, while EtNH3+/EtNH2 is the acid/base set for proton transfer.
Br NaCNEthanolsolvent
H2/Ptor1. LiAlH4/ether2. H2O
NH2
A secondary amine A tertiary alcoholA quaternary ammonium ion
O H2N
Protonation
HO NH
Loss of Leaving group
–H2O
N
H3N+ H2OH2N+
Nucleophilicattack
H2NH
DeprotonationH2N
Protonation
H2NH
N
DeprotonationH2N
Product Imine
Cyclohexanone Ethylamine N-ethylcyclohexanimine
ctivated
g.at nEz ea 50pA
TE E Is
en f w
E'Eign E 2I 2Magento
a 43 EEF
to
zky.oHit Hgtftp.t it't aIt
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(a) (6 pts) Consider the three pairs of structures below. Are they resonance structures, tautomers or different formulas (circle your answer), 2 pts each.
2. (10 pts) Extra credit: Igor's Errors: Igor, your clumsy lab assistant, attempts to earn your favor by running extra reactions at night, without your advice. In each case, the reactions fail. Shown below are five of his failures, showing reagents, conditions, and the product he had intended to form. For each case, write just one or two sentences to explain what went wrong in the box at right. If you can identify a problem intermediate or product that formed instead of the desired material, draw it along with your explanation.
OH O
N
O
N
O
H HResonance structuresTautomersDifferent formulas
Resonance structuresTautomersDifferent formulas
NH2
O
N
O
HResonance structuresTautomersDifferent formulas
CN
CN
+ FAIL!Heat(Diels-Alder)
CN
CN
FAIL!1)HNO3/H2SO42) NaOH/H2O
NH2 NH2
NO2
FAIL!Ether
NH + xs CH3I NCH3CH3
I
FAIL!1) Mg/ether2) H3O+
HO
OBr
O
FAIL!SN2 Williamsonethersynthesis
Cl
+ EtO Na
OEt
I Tfo low IH HH H
for fveA 0 If itµ SE e
w r Mit O
gOA
KYAH
endb v
Evs trans diene cannot
4k be in S cis dieselst feet
eledwnwiearao.byt8YTnzsefedMmetadonatt IND eThe line pairs ofelation0 is in Thearomatic8188kmso not available for gµz
No reef
Is EEEn9Br g atwoPka E µSPI can'tdo SN2 an an 0
spa cartons Br
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3. (10 pts, 1 pt. each) For the following transformations (i-x), choose the appropriate letter from
the "reagent shelf" below. Each box only gets one letter. If needed, you may use the same reagent more than once.
PPh3
NH2
O
N
H H
OH
N
OH
N
OO S S
OH
EtO OEt
C)
1. LiAlH42. H2O
HSSH
A)[H+]
B)
HOOH
D)H+
NH2OH
[H+]G)
1. H2N-NH2 / H+
2. KOH/H2O/heat
E)H+
F)
H)
RCO3H
MgBr
HN
K)
NaCr2O7H2SO4/H2O
I)H+
J)
L)2. H2O
EtOH
[H+]
1.
iii
iii
iv
vi
viii
x
ix
v
vii
I
is acIenami
aµ Il GiViii F dH E I fX L
dO r p
I