Edexcel organic reaction mechanisms

1
Edexcel organic reaction mechanisms
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Homolytic
Free Radical Substitution
Free Radical Addition
Heterolytic
Electrophilic Addition
SN1
SN2
Nucleophilic Substitution
Electrophilic Substitution
Alkylation
Nitration
Br2
Acylation
Nucleophilic Addition
2
Free radical substitution
chlorination of methane
i.e. homolytic breaking of covalent bonds
Overall reaction equation
CH4 Cl2
CH3Cl HCl
Conditions
ultra violet light
excess methane
to reduce further substitution
3
Free radical substitution mechanism
ultra-violet
initiation step
two propagation steps
termination step
minor termination step
4
Further free radical substitutions
Overall reaction equations
CH3Cl Cl2
CH2Cl2 HCl
CH2Cl2 Cl2
CHCl3 HCl
CHCl3 Cl2
CCl4 HCl
Conditions
ultra-violet light
excess chlorine
5
Free radical addition
addition polymerisation of ethene
i.e. homolytic breaking of covalent bonds
Overall reaction equation
n H2CCH2
polyethene
ethene
Conditions
free radical source
(a species that generates free radicals that
allow the polymerisation of ethene molecules)
6
Free radical addition mechanism
initiation step
chain propagation steps
Addition of H2CCH2 repeats the same way until
termination step
polyethene
7
Electrophilic addition
bromine with propene
mechanism
CH3CHCH2
Br2
CH3CHBrCH2Br
1,2-dibromopropane
hydrogen bromide with but-2-ene
mechanism
CH3CHCHCH3
HBr
CH3CH2CHBrCH3
2-bromobutane
8
bromine with propene
Electrophilic addition mechanism
reaction equation
carbocation
1,2-dibromopropane
9
hydrogen bromide with trans but-2-ene
Electrophilic addition mechanism
reaction equation
carbocation
2-bromobutane
10
Nucleophilic substitution
hydroxide ion with bromoethane
mechanism
CH3CH2Br
OH-
CH3CH2OH Br-
(aqueous)
ethanol
hydroxide ion with 2-bromo,2-methylpropane
mechanism
(CH3)3CBr
OH-
(CH3)3COH Br-
(aqueous)
2-methylpropan-2-ol
11
hydroxide ion with bromoethane (SN2)
Nucleophilic substitution mechanism
ethanol
SN2
reaction equation
2(species reacting in the slowest step)
S (substitution)
N(nucleophilic)
12
OH- ion with 2-bromo,2-methylpropane (SN1)
Nucleophilic substitution mechanism
2-methylpropan-2-ol
SN1
reaction equation
1(species reactingin the slowest step)
S (substitution)
N(nucleophilic)
13
Nucleophilic substitution
cyanide ion with iodoethane
mechanism
CH3CH2I (ethanol)
CN-(aq)
CH3CH2CN I-
propanenitrile
cyanide ion with 2-bromo,2-methylpropane
mechanism
(CH3)3CBr
(ethanol) CN-
(aqueous)
(CH3)3CCN Br-
2,2-dimethylpropanenitrile
14
cyanide ion with iodoethane (SN2)
Nucleophilic substitution mechanism
propanenitrile
SN2
2(species reacting in the slowest step)
S (substitution)
N(nucleophilic)
reaction equation
15
CN- ion with 2-bromo,2-methylpropane (SN1)
Nucleophilic substitution mechanism
SN1
2,2-dimethylpropanenitrile
1(species reactingin the slowest step)
S (substitution)
N(nucleophilic)
reaction equation