The document discusses electrophilic aromatic substitution reactions. It describes the nitration of aromatic compounds using concentrated nitric and sulfuric acids at 50°C to add nitro groups. Nitroaromatic compounds are used to make explosives like TNT and primary amines used in azo dyes. The document also describes Friedel-Crafts acylation where an acyl group is added to an aromatic ring using an acyl chloride or anhydride and aluminum chloride catalyst. Examples of both nitration and acylation of various methylbenzene derivatives are shown.

1. © www.chemsheets.co.uk A2 1026 21-Dec-2021

2. + HNO3
+ H2O
conc HNO3
conc H2SO4
50C
NITRATION – Electrophilic substitution
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3. Aromatic NITRO compounds - USES
TNT (trinitrotoluene)

4. Aromatic NITRO compounds - USES
Making primary amines
(used to make azo dyes)
e.g. a yellow azo dye

5. electrophile = NO2
+ (nitronium ion)
HNO3 + 2H2SO4  NO2
+ + 2HSO4
– + H3O+
- H+
NO2
NITRATION – Electrophilic substitution
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6. e.g. 1 methylbenzene + conc HNO3 & conc H2SO4 at 50C to make 2-nitromethylbenzene
Electrophilic
substitution
+ HNO3
+ H2
O
HNO3 + 2H2SO4  NO2
+ + 2HSO4
– + H3O+
- H+
NO2
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7. e.g. 2 methylbenzene + conc HNO3 & conc H2SO4 at 50C to make 4-nitromethylbenzene
Electrophilic
substitution
HNO3 + 2H2SO4  NO2
+ + 2HSO4
– + H3O+
+ HNO3
+ H2
O
- H+
NO2
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8. e.g. 3 1,3-dimethylbenzene + conc HNO3 & conc H2SO4 at 50C to make 2-nitro-1,3-dimethylbenzene
Electrophilic
substitution
HNO3 + 2H2SO4  NO2
+ + 2HSO4
– + H3O+
+ HNO3
+ H2
O
- H+
NO2
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9. AlCl3
Acyl chloride /
acid anhydride
FRIEDEL-CRAFTS ACYLATION –
Electrophilic substitution
+ HCl
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10. USES of Friedel-Crafts reactions
VERY useful in organic synthesis as it is a way
of adding C atoms onto an aromatic ring.
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11. electrophile = RCO+ (acylium ion)
FRIEDEL-CRAFTS ACYLATION
Electrophilic substitution
+ AlCl3
+ AlCl4
-
- H+
AlCl4
– + H+  AlCl3 + HCl
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12. electrophile = RCO+ (acylium ion)
FRIEDEL-CRAFTS ACYLATION
Electrophilic substitution
Cl3
Al
_
+ AlCl3
_
- H+
AlCl3
Cl3
Al
_
+ H+
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13. e.g. 4 methylbenzene with ethanoic anhydride and AlCl3 to make 2-methylphenylethanone
Electrophilic substitution
Cl3
Al
_
+ AlCl3
- H+
AlCl3
Cl3
Al
_
+ H+
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14. e.g. 5 methylbenzene with propanoyl chloride and AlCl3
Electrophilic substitution
+ HCl
+ AlCl3
+ AlCl4
-
- H+
AlCl4
– + H+  AlCl3 + HCl
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15. e.g. 6 nitrobenzene with ethanoyl chloride and AlCl3
Electrophilic substitution
AlCl4
– + H+  AlCl3 + HCl
+ HCl
+ AlCl3 + AlCl4
-
- H+
© www.chemsheets.co.uk A2 1026 21-Dec-2021

16. e.g. 7 1,3-dimethylbenzene with ethanoic anhydride and AlCl3
Electrophilic substitution
Cl3
Al
_
+ AlCl3
- H+
AlCl3
Cl3
Al
_
+ H+
© www.chemsheets.co.uk A2 1026 21-Dec-2021

17. 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
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