Mechanisms in Organic Chemistry
Alkenes Aldehydes or ketones
Halogenoalkanes Arenes Alkanes
Electrophilic
AdditionHBr, Br2,Br2(aq)
Free Radical
Polymerisation
Nucleophilic Addition
Nucleophilic Substitution
SN1
SN2
Electrophilic Substitution
Free Radical Substitution
Electrophilic Addition 2 – Ethene + Br2(hexane)
Br
Br _
+
CC
H
Br
H
H H+
:Br_
CC
H
Br Br
H
H HC C
H
H H
H
home
Electrophilic Addition 3 – Ethene + Br2(aq)
Br
Br _
+
CC
H
Br
H
H H+
:OH2
CC
H
OH Br
H
H HC C
H
H H
H
home:Br_
HBr
Nucleophilic Addition – Reaction of HCN with Carbonyls
C
O
H3C H
C
:O_
H3C H
CN
C
:OH
H3C H
CN
H+
:CN_
+
_
home
C CH3
CH3
H3C
OH
C CH3
CH3
H3C
Br
C CH3
CH3
H3C +
:Br-
+
- :OH-
Nucleophilic Substitution – SN1 Mechanism
Rate = k[C4H9Br]home
CC
H
H H
H
H Br CC
H
H H
H
H OH
:OH-
Nucleophilic Substitution – SN2 Mechanism
Rate = k[C2H5Br][:OH-]
:Br-
home
+ _
(NB Transition state)
Electrophilic Substitution 1 – Nitration of benzene
H2SO4 + HNO3 NO2+ + HSO4
- + H2O
home
+
NO2H+NO2NO2
H+
Electrophilic Substitution 2 – Bromination of benzene
Br2 + AlCl3 Br+ + AlBrCl3-
home
+
BrH+Br Br
HBr
AlCl3
Electrophilic Substitution 3 – Alkylation of benzene
CH3Cl + AlCl3 CH3+ + AlCl4
-
home
+
CH3H+CH3CH3
HCl
AlCl3
Electrophilic Substitution 4 – Acylation of benzene
CH3COCl + AlCl3 CH3CO+ + AlCl4-
home
+
CH3C
O
HCH3+C
OCH3C
O
HCl
AlCl3
Br+
Bromination of methylbenzene – ring substitution
AlBr3
HBr
Br2 + AlBr3 Br+ + AlBr4-
CH3
Br
home
CH3CH3
+
H
Br
Free Radical Substitution 1 – Methane + Cl2
Initiation Cl Clu.v. light
2Cl.
PropagationCH4 + Cl
.
. CH3 + HCl
. CH3 + Cl2 CH3Cl + Cl
.
Termination . CH3 +
. CH3
C2H6
. CH3 +
. Cl
CH3Cl home