Sp2010 Org II Exam #1
Ch 14-17
(100 points)
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1-15) are True or False (15pts)
1)
Benzene is a 6π aromatic compound.
2)
Acylium ions are resonance stabilized.
3)
Pericyclic reactions are ones that take place through a closed loop of
interacting orbitals.
4)
The rate determining step in an electrophilic aromatic substitution is
the endothermic addition of the electrophile.
5)
Fluorobenzene undergoes nitration and bromination reactions slower
than benzene.
6)
During a nucleophilic aromatic substitution via the
addition/elimination pathway, the aromatic compound loses its
aromaticity in the first step, but then regains it in the last step of the
reaction.
7)
Para substitution means a 1,4 arrangement on a benzene ring.
8)
The amino group (-NH2) is a deactivating substituent for electrophilic
aromatic substitution because of its lone pair.
9)
During an electrophilic aromatic substitution, the aromatic substrate
produces a resonance stabilized, non-aromatic cationic intermediate.
10)
11)
Oxetanes are 4 membered rings.
Molecular Orbital theory provides an accurate description of
delocalized π bonding.
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12)
Symmetric di-alkyl ethers undergo acidic cleavage and oxidation
reactions.
13)
The polygon rule is a way to predict π electronic configurations for
aromatic and anti aromatic systems.
14)
Woodward and Hoffman created rules that predicted whether
pericyclic reactions would proceed thermally or photochemical.
15)
Quinones are formed via oxidation of phenols.
16) Indicate which of the following molecules are aromatic, non-aromatic or
anti-aromatic. (Assume all the molecules are planar). (12pts)
CH3
Al
F
B
N
+
CH3
S
+
N
N
H
H
N
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17) Predict the products in the following reactions, paying attention to
regio/stereochemistry where applicable. (24pts)
CH3
Br2, FeBr3
CH3
O
heat
CH3
CO, HCl
CuCl, AlCl3
CO2H
H
Br
H
heat
Br
H3C
OH
1) NaOH
2) CH3CH2I
Excess HBr
O
O
CF3
SO3, H2SO4
Br
Cl2, AlCl3
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18) In each pair, circle the molecule that is more easily protonated. (8pts)
or
or
H
P
S
or
H
N
N
or
N
19) State a piece of experimental evidence that benzene does NOT contain
alternating single and double bonds. (2pts)
20) State the Hammond Postulate. (2pts)
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21) For the following reaction: (12pts)
Br
H-Br
Br
a) label the 1,4 addition product
b) which product is more stable ?
c) which product is the kinetic product ?
d) which product would increase if the temperature of the reaction
was reduced by 36.9oC ?
e) write the mechanism for this reaction.
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22) (5pts) Write the mechanism for the reaction of sulphuric acid and nitric
acid, which produces (+NO2) the Nitronium ion.
O
HO
S
O
O
OH
+
HO
N
O
N
O
O
23) (5pts) Provide reagents for this multistep conversion.
O
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24) Give reagents for the following multistep transformations.
(4+3+4+4 = 15pts)
CH2CH3
CH2CH3
NH2
NH2
in a 1:1 ratio
CO2H
CH2CH3
Cl
Br
NO2
Br
NO2
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BONUS Points (up to 3 points)
Explain the safety lesson learned from the “Whipper Reaction’ story I told in
class.
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