1. Polynuclear Aromatics

2. Napthalene

3. Naphthalene: nomenclature: Mono substituted:α-1- β- 2- Special names:

4. Heat of hydrogenation is –61 Kcal/mole lower than predicted (resonance stabilization energy). Benzene is –36 Kcal/mole lower than predicted. - 61 = - 36 - 25  the second aromatic ring is less stable.

5. Naphthalene, reactions: 1) oxidation:

6. Note: Because naphthalene is sensitive to oxidation, you cannot make naphthoic acids via oxidation of a side chain.

7. 2. Reduction:

8. 3. Electrophilic Aromatic Substitution:

9. Electrophilic aromatic substitution (cont.)

10. Why is EAS in naphthalene mostly to the alpha-position?

11. EAS in syntheses of substituted naphthalenes: Alpha-substitution via halogenation or nitration.

12. Beta-substitution via high temp sulfonation or Friedel-Crafts acylation in nitrobenzene.

13. EAS in substituted naphthalenes: a)With an activating group to EAS in the alpha position  4- plus a little 2- in the beta position  1- b)With a deactivating group to EAS  the other ring, usually alpha ( 5- & 8- )

16. Haworth Synthesis of naphthalene

17. Substituted naphthalenes via Haworth synthesis:

21. Oxidation:

22. Reduction:

23. EAS in anthracene or phenanthrene yields mixtures and is not generally useful. For example, in sulfonation:

25. Haworth synthesis of anthracene

26. Haworth synthesis of phenanthrene