Electrophilic Aromatic Substitution Worksheet - ChemConnections

Adapted from PLTL
Names: ___________________
Chem 227/ Dr. Rusay
Electrophilic Aromatic Substitution
Sec. ______
1. Each of the following reactions is classified as occurring by an electrophilic substitution
mechanism. Complete the following table showing the respective electrophile, the
electrophilic substitution intermediate and provide a two-step mechanistic scheme (use
curved arrows to show the movement of electron pairs) for each of the reactions.
Cl
a.
+ Cl 2
FeCl 3
NO 2
b.
+ HNO 3
H 2 SO 4
SO 3 H
c.
SO 3 , H 2 SO 4
CH 2 CH 3
d.
+ CH 3 CH 2 Cl
AlCl 3
e.
+
HF
f.
+
OH
BF 3
O
g.
+
H 3 C
C
O
AlCl 3
C
CH3
Cl

Electrophile Intermediate Mechanism
a.
b.
c.
d.
e.
f.
g.

2. Consider the following reactions; a) explain the differences in reactivity between A, B, and C. b)
Which reaction is faster C or D Circle one. Explain your answer, and why B does not react.
A
.
B
.
C
.
D
.
H 3 C
H
H
C
C
H
H
+ Br 2
CH 2 Cl 2
BrCH 2 CH 2 Br
+ Br 2
CH 2 Cl 2
no reaction
Br
+ Br 2
FeBr 3
CH 2 Cl 2
Br
CH 3
H 3 C
+ HBr
CH 3
+ HBr
CH 3
CH 3
a)
b) C or D. Circle one.
Explanation:

3. A DVC Chem 227 team of students ran the following two reactions and obtained the products
noted. Which reacts faster Circle your choice. Explain the reasons for your choice and why
the products differ in their respective substitution patterns.
NH 2
NH 2
A
.
H 2 SO 4
versus
SO 3 H
(major product)
O
NHCCH 3
O
NHCCH 3
B
.
H 2 SO 4
SO 3 H

4. Consider the products of the following reactions.
OCH 3
OCH 3
A
.
HNO 3 , H 2 SO 4
versus
NO 2
B
.
OCH
OCH 3 3
HNO 3 , H 2 SO 4
O 2 N
Show a detailed mechanism for each reaction taking care to show all important resonance
structures. Provide energy diagrams (reaction coordinate diagrams) for the two mechanisms.
A: B:

5. Complete the table that follows with reactions & reagents for preparing each of the following
compounds from benzene. (More than one reaction step may be needed to prepare a product.)
CH 2 CN
Br
A
.
COOH
SO 3 H
Br
H
.
B
.
COOH
G
.
C
.
Br
D
.
O
C
O
H C H
CH 3
E
.
NO 2
CO 2 H
F
.
SO 3 H

A
B
C
D
E
F
G
H