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

Mechanism

H E - Y

H E

+

H E

+

H E

+

E

+ H+

Mechanism

Charge o and p

Energy Diagram

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

Filter

Recrystallize frommethanol

Dry

Weigh

m.p.

Wash