1. Original slide prepared for the Free Radical Substitution Edexcel organic reaction mechanisms Click a box below to go to the mechanism Electrophilic Addition Nucleophilic Substitution Electrophilic Substitution Nucleophilic Addition Alkylation Acylation Click here for advice Heterolytic Nitration Free Radical Addition Homolytic Br 2 SN1SN1SN2SN2

2. Original slide prepared for the CH 4 + Cl 2 CH 3 Cl + HCl Overall reaction equation Conditions ultra violet light excess methane i.e. homolytic breaking of covalent bonds to reduce further substitution Free radical substitution chlorination of methane

3. Original slide prepared for the H3CH3C initiation step two propagation steps termination step ultra-violet CH 3 minor termination step Free radical substitution mechanism Cl H 3 C H Cl H Cl Cl H3CH3C H 3 C Cl Cl H3CH3C H 3 C Cl H3CH3C H 3 C CH 3

4. Original slide prepared for the CH 3 Cl + Cl 2 CH 2 Cl 2 + HCl Overall reaction equations Conditionsultra-violet light CH 2 Cl 2 + Cl 2 CHCl 3 + HCl CHCl 3 + Cl 2 CCl 4 + HCl excess chlorine Further free radical substitutions

5. Original slide prepared for the n H 2 C=CH 2 Overall reaction equation polyethene free radical source i.e. homolytic breaking of covalent bonds (a species that generates free radicals that allow the polymerisation of ethene molecules) Free radical addition addition polymerisation of ethene [ CH 2 CH 2 ] n Conditions ethene

6. Original slide prepared for the initiation step Addition of H 2 C=CH 2 repeats the same way until: polyethene Free radical addition mechanism R R R RH 2 C CH 2 H 2 C CH 2 R H 2 C CH 2 H 2 C CH 2 R H 2 C CH 2 CH 2 CH 2 R R(CH 2 ) n CH 2 R(CH 2 ) n CH 2 CH 2 (CH 2 ) m R H 2 C(CH 2 ) m R chain propagation steps termination step

7. Original slide prepared for the Electrophilic addition CH 3 CH=CH 2 + Br 2 CH 3 CHBrCH 2 Br bromine with propene hydrogen bromide with but-2-ene CH 3 CH=CHCH 3 + HBrCH 3 CH 2 CHBrCH 3 2-bromobutane 1,2-dibromopropane mechanism

8. Original slide prepared for the Br Electrophilic addition mechanism CH 3 H H H C C ++ -- H H H C C Br + - carbocation CH 3 H H H C C Br 1,2-dibromopropane bromine with propene reaction equation

9. Original slide prepared for the Electrophilic addition mechanism CH 3 H H C C H H C C H + carbocation CH 3 H H C C BrH 2-bromobutane hydrogen bromide with trans but-2-ene -- ++ Br H reaction equation Br -

10. Original slide prepared for the hydroxide ion with bromoethane ethanol CH 3 CH 2 Br+ OH - CH 3 CH 2 OH + Br - ( aqueous ) Nucleophilic substitution mechanism hydroxide ion with 2-bromo,2-methylpropane 2-methylpropan-2-ol (CH 3 ) 3 CBr+ OH - (CH 3 ) 3 COH + Br - ( aqueous ) mechanism

11. Original slide prepared for the ++ -- CH 3 H Br C H - OH CH 3 H OH C H Br - hydroxide ion with bromoethane (S N 2) Nucleophilic substitution mechanism ethanol reaction equation 2 (species reacting in the slowest step) SN2SN2 S (substitution) N (nucleophilic)

12. Original slide prepared for the ++ -- CH 3 Br C CH 3 - OH Br - OH - ion with 2-bromo,2-methylpropane (S N 1) Nucleophilic substitution mechanism 2-methylpropan-2-ol reaction equation 1 (species reacting in the slowest step) SN1SN1 S (substitution) N (nucleophilic) Br - CH 3 C + OH C CH 3

13. Original slide prepared for the Nucleophilic substitution propanenitrile CH 3 CH 2 I (ethanol)+ CN - (aq)CH 3 CH 2 CN + I - cyanide ion with iodoethane mechanism cyanide ion with 2-bromo,2-methylpropane 2,2-dimethylpropanenitrile (CH 3 ) 3 CBr (ethanol) + CN - (CH 3 ) 3 CCN + Br - ( aqueous ) mechanism

14. Original slide prepared for the ++ -- CH 3 H I C H CN - CH 3 H CN C H I - cyanide ion with iodoethane (S N 2) Nucleophilic substitution mechanism propanenitrile reaction equation 2 (species reacting in the slowest step) SN2SN2 S (substitution) N (nucleophilic)

15. Original slide prepared for the ++ -- CH 3 Br C CH 3 Br - CN - ion with 2-bromo,2-methylpropane (S N 1) Nucleophilic substitution mechanism 2,2-dimethyl propanenitrile 1 (species reacting in the slowest step) SN1SN1 S (substitution) N (nucleophilic) Br - CH 3 C + CN C CH 3 CN - reaction equation