Anthracene

It deals with preparation and reaction of anthracene

1. Anthracene

2. Structure of Anthracene

3. Introduction It is obtained from oil fraction of coal tar. The crude anthracene contains Phenanthrene and carbazole Phenanthrene Carbazole

4. Purification of anthracene Anthracene is washed with Solvent naphtha which dissolve phenanthrene and remaining solid is then washed with pyridine which dissolve the Carbazole .

5. Solvent naphtha A flammable liquid distillate containing mainly xylene and aromatic hydrocarbon. It has high boiling point than ligroin. It is obtained by cracking of petroleum. It is used as solvent.

6. Structure Xylene Ligroin Light ligroin; Light petroleum; pether

7. Isomers of xylene

8. Ligroin  is the petroleum fraction consisting mostly of C 7  and C 8  hydrocarbons and boiling in the range 90‒140 ℃ (194–284 °F). The fraction is also called heavy naphtha .  Ligroin is used as a laboratory solvent. Products under the name ligroin can have boiling ranges as low as 60‒80 ℃ and may be called light naphtha . Petroleum ether  is the  petroleum fraction consisting of aliphatic hydrocarbons and boiling in the range 35‒60 °C, and commonly used as a laboratory  solvent .  Despite the name, petroleum ether is not classified as an ether; the term is used only figuratively, signifying extreme lightness and volatility.

9. Ligroin is assigned the CAS Registry Number 8032-32-4, which is also applied to many other products, particularly the lower boiling ones, called petroleum spirit, petroleum ether, and petroleum benzine . "Naphtha" has the CAS Registry Number 8030-30-6, which also covers petroleum benzine and petroleum ether: that is, the lower boiling point non-aromatic hydrocarbon solvents .

10. Structure of Anthracene When a nthracene react with bromine gives bromo anthracene

11. Structure of Anthracene

12. This reactions suggest that anthracene contain two benzene ring. The presence of two benzene ring is confirmed by the fact that on fusion with KOH at 250C. It forms anthroquinone On oxidation gives two molecules of benzoic acid Structure of Anthracene

13. It contain 14 carbon and 10 hydrogen atom,the middle ring must be closed to retain the quadrivalency of carbon. The structure of anthracene is three benzene rings are fused in a linear manner. Structure of Anthracene

14. Synthesis of Anthracene

15. Friedel craft reaction Two molecules of benzyl chloride in the presence of AlCl3 from 9:10dihydroanthracene, readily eliminates two hydrogen atom under the condition of the experiment to form anthracene

16. Friedel craft condensation Anthracene is formed by condensation between benzene and methylene bromide

17. Friedel craft condensation Anthracene is formed by condensation between benzene and Acetylene tetra bromide

18. By heating ortho bromo benzyl bromide with sodium; the product dihydro anthracene is converted into anthracene by mild oxidation.

19. Elbs reaction

20. It is prepared by refluxing ketone under 400-450C. The yield is low. But Elb’s reaction is often used to prepare polynuclear hydrocarbon. Elbs reaction

21. Diel’s alder reaction

22. Anthraquinone Anthracene 1:4Naphtha Quinone 1,4 butadiene

23. Position of double bond

24. Structure I was accepted by may because synthesis of anthracene by treating benzene with acetylene tetra bromide.

25. Synthesis of naphthalene from anthracene ondicates the absence of para bond

26. Anthracene adds on maleic anhydride, the addition occur in the middle ring[because it behave as diene ]

27. X ray analysis revealed that all the carbons are lying in a same plane. Anthracene is resonance hybrid of four structure

28. Anthracene is an alternate hydrocarbon Pie-electron densities are unity at all position. The self polarisability order is 9<1<2 Position 9 will be more reactive.

29. Isomerism of anthracene

30. Isomerism of anthracene Three possible mono substitution product α , β and ϒ [ meso ]. There are 15 possible disubstitution product if both the substituents are similar. If the substituents are not similar than large number of isomers are possible.

31. Properties of anthracene Colorless solid Melting point 216 C It gives blue fluorescence. It is insoluble in water and sparingly soluble in organic solvent. It is very reactive in 9: 10 position A saturated solution of anthracene in xylene on exposure to light forms crystals of the dimer [ dianthracene – paranthracene ]

32. Xray analysis revealed that two anthracene molecule are linked in 9 th and 10 th position

33. It adds on one molecule of oxygen to form peroxide

34. It forms a red picrate . It undergoes diels alder reaction It reduced in sodium ethanol forms 9:10 dihydroanthracene .

35. Anthracene treated with chlorine forms dichloro anthracene.when it is treated with alkali or HCl it gives 9 chloro anthracene

36. Anthracene treated with nitric acid underwent oxidation to anthroquinone

37. Synthesis of phenanthrene

38. This is trans annular tautomerism Hydrogen atom migrates across X ray reveals that solid anthrone does not exist in anthranol [ enol form]