COOCH3
HNO3, H2SO4
COOCH3
NO2
COOCH3COOHCH3OH
H2SO4
Nitration of Methyl Benzoate
A B C50% 50%
Yield =
25%
Multistep Synthesis
X Ortho
Meta
Para
Ortho Meta Para
X 2
3
4
5
6
Number Ring
(CH3)3COH (CH3)3CClHCl
Nucleophilic Aliphatic Substitution
NO2
++
H NO2
Electrophilic Aromatic Substitution
E
E+
+ H+
The electrophile REPLACES H+
ARENE SUBSTITUTION
H E - Y
H E
+
H E
+
H E
+
E
+ H+
Mechanism
NO2
HNO3
H2SO4
Nitrobenzene
Nitration of Benzene
Nitronium Ion
HONO2 + 2 H2SO4 NO2+ + H3O+ + 2 HSO4
-
Nitration Reagent
HNO2
+ H NO2
+
NO2
+ H+
Nitration Mechanism
G
G G
G
Second Group. Where go? How fast?
Multiple Substituents
CH3
CH3
NO2
CH3
NO2
CH3
NO2
HNO3
63% 3% 34%
Nitration of Toluene
CH3NO2
H
CH3NO2
H+
+ +
CH3
NO2
H
CH3
NO2
H
CH3
NO2
H
CH3
NO2H
CH3
NO2H
+
+
+
+ ++
ORTHO
META
PARA
Compare o, m, p
G
Favor: ORTHO and PARA.
Electron Donating
Ortho
Para
Electron Donating Groups
CF3
HNO3
H2SO4
CF3
NO2
CF3
NO2
CF3
NO2
6% 91% 3%
Nitration of trifluoromethylbenzene
CF3 + charge here bad
Electron Withdrawing Groups
CF3H
NO2
CF3H
NO2
CF3H
NO2
CF3
H
NO2
CF3
H
NO2
Ortho
Meta
Para
++ +
+
+
+
+ ++
Compare o, m, p
Z
Meta Directors and DEACTIVATING
ElectronWithdrawing Group
Meta Product
Electron Withdrawing Groups
-NH2
-OH
-NHR
-OR
-OCR
-NHCR
O
O
Very Activating
Ortho-Para Directors
-R
-Ar
-Halogens
Activating
Activating
Deactivating
Ortho-Para Directors
-CR
O
-COHO
-CN
-SO3H
-NO2
Meta Directors
COOCH3
HNO3, H2SO4
COOCH3
NO2
Side Products
meta
COOCH3
NO2
NO2
COOCH3 COOCH3
NO2O2N
Main Reaction
1. Dissolve methyl benzoate in H2SO4
2. Mix HNO3 and H2SO4 at 0oC
3. Add HNO3 / H2SO4
dropwise to methyl benzoate at 0oC
Procedure
4. Let stand at roomtemperature 10 minutes
5. Pour onto ice
Procedure
Recrystallize frommethanol
Dry
Weigh
m.p.
Wash