Química Orgânica

1. Mechanisms in Organic
Chemistry
Alkenes Aldehydes
or ketones
Halogenoalkanes Arenes Alkanes
Electrophilic
Addition
HBr, Br2,Br2(aq)
Free Radical
Polymerisation
Nucleophilic
Addition
Nucleophilic
Substitution
SN1
SN2
Electrophilic
Substitution
Free Radical
Substitution

2. Electrophilic Addition 1 – Ethene + HBr
H
Br
d
_
d+
C
C
H
H
H
H H
+
:Br
_
C
C
H
Br H
H
H H
C C
H
H H
H
home

3. Electrophilic Addition 2 – Ethene + Br2(hexane)
Br
Br
d
_
d+
C
C
H
Br
H
H H
+
:Br
_
C
C
H
Br Br
H
H H
C C
H
H H
H
home

4. Electrophilic Addition 3 – Ethene + Br2(aq)
Br
Br
d
_
d+
C
C
H
Br
H
H H
+
:OH2
C
C
H
OH Br
H
H H
C C
H
H H
H
home
:Br
_
HBr

5. Nucleophilic Addition – Reaction of HCN with Carbonyls
C
O
H3C H
C
:O
_
H3C H
CN
C
:OH
H3C H
CN
H+
:CN
_
d+
d
_
home

6. C CH3
CH3
H3C
OH
C CH3
CH3
H3C
Br
C CH3
CH3
H3C
+
:Br-
d+
d- :OH-
Nucleophilic Substitution – SN1 Mechanism
Rate = k[C4H9Br]
home

7. C
C
H
H H
H
H Br C
C
H
H H
H
H OH
:OH-
Nucleophilic Substitution – SN2 Mechanism
Rate = k[C2H5Br][:OH-]
:Br-
home
d+ d
_
(NB Transition state)

8. Electrophilic Substitution 1 – Nitration of benzene
H2SO4 + HNO3 NO2
+ + HSO4
- + H2O
home
+
NO2
H
+NO2
NO2
H+

9. Electrophilic Substitution 2 – Bromination of benzene
Br2 + AlCl3 Br+ + AlBrCl3
-
home
+
Br
H
+Br Br
HBr
AlCl3

10. Electrophilic Substitution 3 – Alkylation of benzene
CH3Cl + AlCl3 CH3
+ + AlCl4
-
home
+
CH3
H
+CH3
CH3
HCl
AlCl3

11. Electrophilic Substitution 4 – Acylation of benzene
CH3COCl + AlCl3 CH3CO+ + AlCl4
-
home
+
CH3
C
O
H
CH3
+C
O
CH3
C
O
HCl
AlCl3

12. Br+
Bromination of methylbenzene – ring substitution
AlBr3
HBr
Br2 + AlBr3 Br+ + AlBr4
-
CH3
Br
home
CH3 CH3
+
H
Br

13. Free Radical Substitution 1 – Methane + Cl2
Initiation Cl Cl
u.v. light
2Cl
.
Propagation CH4 + Cl
. . CH3 + HCl
. CH3 + Cl2 CH3Cl + Cl
.
Termination . CH3 +
. CH3
C2H6
. CH3 +
. Cl CH3Cl
home

14. Free Radical Addition Polymerisation of Ethene
home
R
C C
H
H H
H
C C
H
H H
H
C
C
H
H H
H
R
C
C
H
H H
H
R
C
C
H
H H
H
R C
C
H
H H
H
Propagation
Initiation
R R
heat
2R
.