Problem Set 4
1.
Complete the following sequences of reactions. Assume the para product is
formed when a mixture of ortho/para is predicted.
CH3
Br2
HNO3
Br2
FeBr3
H2SO4
FeBr3
CH3
HNO3
Cl
Br2
H2SO4
AlCl3
FeBr3
Na2Cr2O7
HNO3
Br2
H2SO4
H2SO4
FeBr3
KMnO4
Br2
H2O
FeBr3
CH3
O
CH3
Cl
Ph
AlCl3
2. (a) Furan (C4H4O) is a common oxygen-containing heterocyclic aromatic compound.
Experiments show that under electrophilic conditions, furan is preferentially activated
adjacent to the ring oxygen (2-position). Explain, based on your knowledge of the
intermediate in the reaction, why substitution occurs in the 2-position rather than the
3-position. I highly suggest you use resonance forms!
Br2
O
O
FeBr3
Br
O
not
Br
(b) The solvolysis reaction of 2-chloro-2-phenylpropane in aqueous acetone is an
SN1 carbocation process that yields 2-phenyl-2-propanol as the principle product.
Substituents affect the rate of this process. Indicate whether the two compounds on
the right below undergo solvolysis in aqueous acetone faster or slower than 2chloro-2-phenylpropane.
Cl
2-chloro-2-phenylpropane
Cl
Cl
OMe
NO2
Briefly, but clearly, explain your ordering from above. I highly suggest you use
resonance forms.
3. Provide the missing compounds and reagents in the reaction scheme below.
Indicate stereochemistry where appropriate.
1. Mg, ether
HBr
2. H3O+
Cl
1.
Mg
ether
POCl3
H3O+
HB
r
Cl/AlCl3
pyridine
KOtBu
NBS
O
2. H3O+
HNO3 H2SO4
Cl
1. NaNO2
NH2
O
2. CuCN
–CN
NaOH
1.
1. Br2
OH
Br
2.
2. SnCl2
HCl
O
KMnO4
4. Provide the missing compounds and reagents in the reaction scheme below.
Indicate stereochemistry where appropriate.
Br
HNO3
NaOH
H2SO4
1. Cl2
2. SnCl2
HCl
O
Cl/AlCl3
Br
H2N
1. NaNO2
2. Cu2O
H2O
1.
2. H3O+
1. Mg, ether
NBS
2.
OH
Cl
O
KMnO4