1. Substitution reactions of benzene L.O.:  Outline the mechanism for mononitration and monohalogenation of benzene.

2. Homework Q: 1&3 Extension: Q2

3. Recap questions What are the three sources of evidence which led to the delocalised electron model of benzene? Why is benzene less reactive than alkenes?

4. Starter activity What is the name for the reaction between bromine and ethene? Draw the mechanism for it Define the term “nucleophile”

5. Reactions involving benzene Benzene is more stable than alkenes, therefore less reactive Won’t react with halogens at RTP without a catalyst Will usually undergo electrophilic substitution reactions

6. STRUCTURE OF BENZENE

9. NITRATION nitrobenzene Conditionsconc HNO 3 conc H 2 SO 4 catalyst 50ºC

10. Electrophile curly arrow

11. -H + Formation of electrophile HNO 3 + H 2 SO 4 + HSO 4 - + H 2 O NO 2 + Reaction of electrophile with aromatic compound NO 2 + + H nitronium ion NITRATION – ELECTROPHILIC SUBSTITUTION H + + HSO 4 - → H 2 SO 4

12. NITRATION Equation (name product) Conditions Mechanism

13. NITRATION 2-methylnitrobenzene Conditionsconc HNO 3 conc H 2 SO 4 catalyst 50ºC

14. NITRATION Uses of nitro compounds: 1)as explosives 2)to make aromatic amines (used to make dyes) 1,3,5-trinitrotoluene TNT

15. Name the mechanism for this reaction. Electrophilic substitution

18. Reactions with halogens React in the presence of a catalyst called a halogen carrier Benzene + Chlorine  Chlorobenzene + Hydrochloric acid Common halogen carriers are FeCl 3, AlCl 3 and AlBr 3

19. Reactions with halogens –mechanism of reaction Electrophilic substitution Br 2 + FeBr 3 → Br + + FeBr 4 - The halogen carrier reacts with the halogen molecule to produce the halide ion which then goes on to react with the benzene

20. o OCR past paper Q

21. Reactivity of cyclohexene vs benzene (4 marks)

22. Comparing benzene with alkenes o benzene is more stable (1) o benzene π electrons are delocalised (1) o benzene has lower electron density (1) o so bromine is less polarised /attracted to it / benzene is less susceptible to electrophiles (1)

23. Finishing off Draw the complete mechanism for the nitration of benzene. Include the reaction conditions and catalyst Draw the complete reaction for the chlorination of benzene