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Reactions of arenes

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Reactions of arenes. L.O.: Outline the mechanism of nitration. Outline the mechanism of of acylation. Identify the reactive intermediates involved in nitration and acylation. Name the mechanisms of both reactions. STRUCTURE OF BENZENE. STRUCTURE OF BENZENE. STRUCTURE OF BENZENE. NITRATION. - PowerPoint PPT Presentation
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Reactions of arenes L.O.: Outline the mechanism of nitration. Outline the mechanism of of acylation. Identify the reactive intermediates involved in nitration and acylation. Name the mechanisms of both reactions.
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Page 1: Reactions of arenes

Reactions of arenes

L.O.:

Outline the mechanism of nitration. Outline the mechanism of of acylation. Identify the reactive intermediates involved

in nitration and acylation. Name the mechanisms of both reactions.

Page 2: Reactions of arenes

C C

C

CC

C HH

H H

H H

STRUCTURE OF BENZENE

Page 3: Reactions of arenes

STRUCTURE OF BENZENE

Page 4: Reactions of arenes

STRUCTURE OF BENZENE

Page 5: Reactions of arenes

NITRATION

+ HNO3 + H2O

NO2

nitrobenzene

Conditions conc HNO3

conc H2SO4 catalyst

50ºC

Page 6: Reactions of arenes

-H+

Formation of electrophile

HNO3

+ 2 H2SO4 + 2 HSO4-

+ H3O+

NO2

+

Reaction of electrophile with aromatic compound

NO2

NO2+ NO2

+H

nitronium ion

NITRATION – ELECTROPHILIC SUBSTITUTION

Page 7: Reactions of arenes

NITRATION

Equation (name product)

Conditions

Mechanism

CH3CH3

NO2

Page 8: Reactions of arenes

NITRATION

2-methylnitrobenzene

Conditions conc HNO3

conc H2SO4 catalyst

50ºC

CH3

+ HNO3 + H2O

CH3

NO2

Page 9: Reactions of arenes

NITRATION

Uses of nitro compounds:

1) as explosives

2) to make aromatic amines (used to make dyes)

CH3

NO2

NO2

O2N

1,3,5-trinitrotolueneTNT

Page 10: Reactions of arenes

Name the mechanism for this reaction.

Electrophilic substitution

Page 11: Reactions of arenes
Page 12: Reactions of arenes
Page 13: Reactions of arenes

Draw the electron arrangement (dot-cross diagram) of aluminium chloride.

Page 14: Reactions of arenes

FRIEDEL-CRAFTS ACYLATION

aromatic ketone

Conditions AlCl3 catalyst

R C

O

Cl+

CR O

+ HCl

+

CR O

+ R C

O

O C

O

R R C

O

OH

Page 15: Reactions of arenes

FRIEDEL-CRAFTS ACYLATION

WARNING! - do not mix

Friedel-Crafts acylation & other acylations

(needs AlCl3)

Swap H on benzene ring

for acyl group

H H N

H

R

H O R

Swap H on O/N

for acyl group

Page 16: Reactions of arenes

FRIEDEL-CRAFTS ACYLATION

WARNING! - Classic question to test this

NH2 NHCOCH3

CH3COCl

H replaced is on N not benzene ring.

This is NOT Friedel-Crafts acylation!

Page 17: Reactions of arenes

Formation of electrophile

AlCl3

+ RCOCl +

AlCl4–+

C

O

R

acylium ion

OR

AlCl3

+ R-C-O-C-R +

+

C

O

R

acylium ion

O

O R-C-O-AlCl3

O

FRIEDEL-CRAFTS ACYLATION – ELECTROPHILIC SUBSTITUTION

Page 18: Reactions of arenes

-H+

Reaction of electrophile with aromatic compound

CC

+H+

C

O

R

O

RO

R

FRIEDEL-CRAFTS ACYLATION – ELECTROPHILIC SUBSTITUTION

AlCl4– + H+ AlCl3 + HCl

+ H+ + AlCl3– R-C-O-AlCl3

O

R-C-OH

O

or

Regeneration of catalyst

Page 19: Reactions of arenes

Equation

Conditions

Mechanism

FRIEDEL-CRAFTS ACYLATION

CH3CH3

CO CH2CH3

Page 20: Reactions of arenes

Conditions AlCl3 catalyst

FRIEDEL-CRAFTS ACYLATION

CH3

CO CH2CH3

CH3

+ CH3CH2 C

O

Cl+ HCl


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