Chemistry 213
Clark College
Homework 2: Benzene and Aromatic Compounds II
Due Wednesday, April 23, 2008, by 4 pm, in my mailbox in APH 203.
1. HW#1, problem 4.
Starting from benzene or toluene, give the reagents necessary to make the following molecules. (Some
may take more than one step)
Cl
AlCl3
NBS
h!
NBS
h!
H2SO4
Br2
FeBr3
O
Br
Br
O
Br
Mg0
O
HO3S
O
OH
1)
2)
O
H
3) H+
Cl
AlCl3
HNO3
H2SO4
NO2
Br2
FeBr3
Br
O
O
NH2
H2
Ni
Cl
HCl
Zn(Hg)
AlCl3
Cl
AlCl3
Homework 2
Spring 2008
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Chemistry 213
Clark College
2. HW#1, problem 5.
Predict the products for the following reactions. If more than one major product can form, give all major
products.
O
O
O
HNO3
OH
OH
H2SO4
NO2 O2N
O
Cl
OH
O
Cl
Cl
Cl
Cl
AlCl3
NO2
O
NO2 O
NO2
NO2
This one may not form
due to steric hinderance!
1) KMnO4, !
CH3CH2Cl
AlCl3
NH2
2)
H+,
OH
H2O
NH2
H2SO4
O
NH2
SO3H
SO3H
Homework 2
Spring 2008
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Chemistry 213
Clark College
3. HW#1, problem 8.
3-Nitrofuran reacts with bromine in the presence of iron (III) bromide to form a mixture of three
monobrominated products.
NO2
Br2
FeBr3
O
three monobrominated products
a. Propose structures for the three possible products.
NO2
O
Br
Br
NO2
NO2
Br
O
O
b. Draw resonance forms for the cationic intermediates leading to each of your three
products.
O
N O
H
Br
O
O
N O
H
Br
O
O
N O
H
Br
O
O
Br H N O
Three resonance structures, but one is very badit puts two positive charges next to each other!
O
Br H N O
Only two resonance structures.
O
O
O
N O
Br
H
O
Br
O
N O
O
N O
H
O
Br
H
O
Three reasonable, non-offensive
resonance structures
c. Based on your resonance forms, predict which of the three products will be the major
product. Explain your choice.
Homework 2
Spring 2008
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Chemistry 213
Clark College
4. For each set of benzene derivatives below, circle the compound that will be more reactive toward
electrophilic aromatic substitution. Give brief explanations for your choices.
A
B
CH3
CH3
O
O
CH3
O
C
CH3
O
NH2
H
N
H
O
O
O
A: When an amide is bonded through the carbonyl group, the partially-positive carbonyl carbon is
bonded to the ring, and is an electron withdrawing group. This group destabilizes the carbocation
intermediate formed during electrophilic aromatic substitution, making the reaction harder. When
the amide is bonded through the nitrogen, the lone pair on the nitrogen can be donated into the
carbocation intermediate, further delocalizing the charge and stabilizing the intermediate.
B: The ester oxygen can donate electron density into the ring, but the carbonyl carbon next to it
pulls electron density away, which decreases the electron-donating potential of the group. The
oxygen of the ether can freely donate electron density into the ring, without any competing effects.
5. Road Map. Provide the products in the following synthetic scheme.
OH
SOCl2
pyridine
A
Cl
AlCl3
1) BH3
2) OH-, H2O2,
H2O
B
C10H12
Cl
SOCl2
pyridine
AlCl3
E
D
HO
C
C10H12
(or this, with C+ rearrangement!)
Homework 2
Spring 2008
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Chemistry 213
Clark College
6. Road Map II. Provide the reagents for the following synthetic scheme.
Br
Br2
FeBr3
O
Br
Cl
1) Mg
2) O
OH
3) H+
AlCl3
O
O
PBr3
Pyr
NH2
Br
NH3
DMSO
O
O
7. Benzene reacts with an acid chloride, in the presence of AlCl3, to yield compound F.
a. From the NMR data provided for compound F, determine the structure of the acid chloride.
NMR for compound F (C10H12O):
8.0 ppm, m, 2H; 7.5 ppm, m, 3H; 3.5 ppm, m, 1H; 1.2 ppm, d, 6H.
O
O
Cl
1) AlCl3
2) H2O
b. What is the product formed when compound F reacts with hot, fuming sulfuric acid?
Homework 2
Spring 2008
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Chemistry 213
Clark College
O
SO3H
Homework 2
Spring 2008
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