POC-II UNIT 1

1. 1
UNIT I: Benzene and its
derivatives
1. Reactions of benzene - nitration,
sulphonation, halogenation reactivity,
2. Friedel crafts alkylation- reactivity,
limitations,
3. Friedel crafts acylation

2. 2

3. 3

4. 4

5. 5

6. 6

7. 7

8. 8

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10. 10

11. 11

12. 12

13. 13

14. 14

15. 15

16. 16

17. 17

18. https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/intro1.htm#contnt
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19. 19

20. Electrophilic Aromatic Substitution
20

21. Reaction
Type
Typical Equation
Electrophile
E(+)
Halogenation
:
C6H6
+ Cl2 & heat
FeCl3 catalyst
——>
C6H5Cl + HCl
Chlorobenzene
Cl(+) or Br(+)
Nitration: C6H6
+ HNO3 & heat
H2SO4 catalyst
——>
C6H5NO2 + H2O
Nitrobenzene
NO2
(+)
Sulfonation: C6H6
+ H2SO4 + SO3
& heat
——>
C6H5SO3H + H2O
Benzenesulfonic
acid
SO3H(+)
Alkylation:
Friedel-
Crafts
C6H6
+ R-Cl & heat
AlCl3 catalyst
——>
C6H5-R + HCl
An Arene
R(+)
Acylation:
Friedel-
Crafts
C6H6
+ RCOCl & heat
AlCl3 catalyst
——>
C6H5COR + HCl
An Aryl Ketone
RCO(+)
21

22. 22

23. Two-step mechanism has been proposed for these
electrophilic substitution reactions.
In the first, slow or rate-determining, step the
electrophile forms a sigma-bond to the benzene
ring, generating a positively
charged benzenonium intermediate.
In the second, fast step, a proton is removed from
this intermediate, yielding a substituted benzene
ring.
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25. 25

26. https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/benzrx1.
htm
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