OWLS: Electrophilic Aromatic Substitution Solutions - UCLA

β-Elimination: Found in E2.
H OCH 3
I
+ HOCH 3 + I
Electrophilic addition to pi bond: Found in some carbon-carbon pi bond addition
reactions and EAS.
H OH 2
+ H 2O
Resonance: Not really a mechanism step because the resonance contributors have no
lifetime (only the resonance hybrid really exists). Included because it is common in
reaction mechanisms.
2. (a) Cl Cl AlCl 3 Cl Cl AlCl 3
O
O CH 3
Cl Cl AlCl 3
O
O CH 3
Cl H Cl AlCl 3
O
O CH 3
Cl H
O CH 3
Cl
O
O CH 3
Cl H
OWLS: Electrophilic Aromatic Substitution Solutions 2
O
O
O CH 3
Cl H
O
O CH 3
Cl H
The ester group is large enough to cause the para isomer to be formed in greater
amount than the ortho isomer.
(b) To determine which reaction is faster, compare the rate-determining steps of the
two reactions. For any EAS mechanism, the rds is the step in which the aromatic