1. Arenes : compounds containing both aliphatic and aromatic parts. Alkylbenzenes Alkenylbenzenes Alkynylbenzenes Etc. Emphasis on the effect that one part has on the chemistry of the other half. Reactivity & orientation

2. Example: ethylbenzene EAS in the aromatic part -CH 2 CH 3 activates and directs ortho- & para- Free radical halogenation in the side chain -C 6 H 5 activates and directs benzyl

3. Alkylbenzenes, nomenclature: Special names

4. others named as “alkylbenzenes”:

5. Use of phenylC 6 H 5 - = “phenyl” do not confuse phenyl (C 6 H 5 -) with benzyl (C 6 H 5 CH 2 -)

6. Alkenylbenzenes, nomenclature:

7. Alkynylbenzenes, nomenclature:

8. Alcohols, etc., nomenclature:

9. Alkylbenzenes, syntheses: 1.Friedel-Crafts alkylation 2.Modification of a side chain: a) addition of hydrogen to an alkene b) reduction of an alkylhalide i) hydrolysis of Grignard reagent ii) active metal and acid c) Corey-House synthesis

10. Modification of side chain:

11. Friedel-Crafts: Ar-H + R-X, AlCl 3  Ar-R + HX Ar-H + R-OH, H +  Ar-R + H 2 O Ar-H + alkene, H +  Ar-R

14. Friedel-Crafts limitations: a)Polyalkylation b)Possible rearrangement c)R-X cannot be Ar-X d)NR when the benzene ring is less reactive than bromobenzene e)NR with -NH 2, -NHR, -NR 2 groups

15. polyalkylation The alkyl group activates the ring making the products more reactive that the reactants leading to polyalkylation. Use of excess aromatic compound minimizes polyalkylation in the lab.

16. The electrophile in Friedel Crafts alkylation is a carbocation: R-X + AlX 3  R+ R-OH + H +  R+ | | — C = C — + H +  R+ Carbocations can rearrange! 

17. rearrangement

19. R-X cannot be Ar-X

20. NR with rings less reactive than bromobenzene -CHO, -COR -SO 3 H -COOH, -COOR -CN -NR 3 + -NO 2

21. NR with –NH 2, -NHR, -NR 2

22. Friedel-Crafts limitations: a)Polyalkylation b)Possible rearrangement c)R-X cannot be Ar-X d)NR when the benzene ring is less reactive than bromobenzene e)NR with -NH 2, -NHR, -NR 2 groups In syntheses it is often best to do Friedel-Crafts alkylation in the first step!

23. Alkylbenzenes, reactions: 1.Reduction 2.Oxidation 3.EAS a) nitration b) sulfonation c) halogenation d) Friedel-Crafts alkylation 4.Side chain free radical halogenation

24. Alkylbenezenes, reduction: NR H 2, Ni 300 o C, 100 atm. CH 3

25. Alkylbenezenes, oxidation: NR KMnO 4 heat CH 3

27. Oxidation of alkylbenzenes. 1) Syn 2) identification C 8 H 10 :

28. Alkylbenzenes, EAS -R is electron releasing. Activates to EAS and directs ortho/para

29. Alkylbenzenes, free radical halogenation in side chain: benzyl free radical

31. Alkenylbenzenes, syntheses: 1.Modification of side chain: a) dehydrohalogenation of alkyl halide b) dehydration of alcohol c) dehalogenation of vicinal dihalide d) reduction of alkyne (2. Friedel-Crafts alkylation)

32. Alkenylbenzenes, synthesis modification of side chain

33. Alkenylbenzenes, synthesis Friedel-Crafts alkylation not normally used for alkenylbenzenes. an exception:

35. Alkenylbenzenes, reactions: 1.Reduction 2.Oxidation 3.EAS 4.Side chain a) add’n of H 2 j) oxymercuration b) add’n of X 2 k) hydroboration c) add’n of HXl) addition of free rad. d) add’n of H 2 SO 4 m) add’n of carbenes e) add’n of H 2 On) epoxidation f) add’n of X 2 & H 2 Oo) hydroxylation g) dimerizationp) allylic halogenation h) alkylationq) ozonolysis i) dimerizationr) vigorous oxidation

36. Alkenylbenzenes, reactions : reduction

37. Alkenylbenzenes, reactions oxidation

38. Alkenylbenzenes, reactions EAS?

40. Alkenylbenzenes, reactions s ide chain :

41. Benzyl carbocation

44. 100 syn-oxidation; make a model!

45. Alkynylbenzenes, syntheses: Dehydrohalogenation of vicinal dihalides

46. Alkynylbenzenes, reactions: 1.Reduction 2.Oxidation 3.EAS 4.Side chain a) reductione) as acids b) add’n of X 2 f) with Ag + c) add’n of HXg) oxidation d) add’n of H 2 O, H +

47. Alkynylbenzenes, reactions: reduction anti- syn-

48. Alkynylbenzenes, reactions: oxidation

49. Alkynylbenzenes, reactions EAS?

50. Alkynylbenzenes, reactions: side chain:

52. Arenes: alkylbenzenes alkenylbenzenes alkynylbenzenes As expected, but remember that you cannot do EAS on alkenyl- or alkynylbenzenes.