1. INTRODUCTION & CLASSIFICATION 2. NAPTHALENE 3. ANTHRACENE 4. PHENANTHRENES 5. DIPHENYL METHANE 6. STILBENE 7. TRIPHENYLMETHANE THANK YOU

1. POLY AROMATIC
HYDROCARBONS
Made by- PRIYANSHA SINGH
Roll No.- 1738
UNIVERSITY INSTITUTE OF PHARMACEUTICAL SCIENCES
PANJAB UNIVERSITY

2. Isolated
Linear
Polynuclear Hydrocarbons
Benzenoid Non- Benzenoid
Fused rings
Angular
Poly-nuclear aromatic hydrocarbons are composed
by two or more benzene rings

3.  Benzenoid: Similar to benzene in structure or
linkage; having an aromatic ring system.
 Fused or condensed ring system: When
two rings share a pair of carbon atoms, the
rings are said to be fused rings.
2
1
3
4
6
6
5
4
2
1
5
3
Isolated ring
Biphenyl or diphenyl
o m
m
o
p
o
m o
m
p

4. NAPTHALENE (C10H8)
Shows aromatic properties
Satisfy Huckel’s rule (4n+2)
=(4*2+2)=10

5. All C=C are not same (X-ray diffraction study)
C1=C2=1.36 Å
C2=C3=1.40 Å
Resonance energy of naphthalene is 61 Kcal/mol
Benzene, 36 Kcal/mol
 2nd aromatic ring is less stable (61-36)=25
Kcal/mol
 Naphthalene is less aromatic (more reactive) than
benzene because it has less resonance stabilizing
energy as compared to 2 individual benzene
molecules.

6. Structure elucidation of naphthalene
1. Molecular Formula: C10H8
2.
So naphthalene contains the skeleton

7.  So nitro group is present in benzene ring.
Nitration basically means reaction with
HNO3/H2SO4
3.
4.
 The benzene ring in phthalic acid
produced by oxidation of amino-
naphthalene is not the same ring is
that obtained by oxidation of nitro
naphthalene.

8.  i.e. Naphthalene contains two benzene rings
and we can explain this by this equation

9. The structure of naphthalene is confirmed by
method of its synthesis
Howarth method

10. Other way of cyclization

11.  The reaction occurs if R is o- or p- directing
group such as NH2, NHR, OH, OR, R, halogen.
 If R is m- directing group (e.g. NO2, CN, COOH,
COCH3, SO3H) no reaction occur.
 The above reaction gives -substituted
naphthalene.

12. Synthesis of 1-alkyl naphthalene

13. From -benzylidene – propenoic acid

14. Reduction

15. Oxidation

16. Addition of Cl2 / Br2

17. Naphthalene undergoes ES mostly at alpha-position
Resonance forms determine higher reactivity at C-1
 C-1 attack has 2 resonance structures with benzene rings
 C-2 attack has only 1 resonance structure with a benzene ring
 The most stable intermediate (C-1 attack) gives faster reaction
Attack at C-2
Attack at C-1
Electrophilic substitution reaction

18. At position 1; carbocation intermediate stabilize by two
resonance within one benzene ring.
So carbocation is more stable position 1 than 2

20.  The lower stability of 1-S is attributed to the steric
interaction between the sulfonic group and the
hydrogen atom in the 8-position.
Sulfonation

21. Summary of naphthalene reactions

22. Medicinal uses of Naphthalene
 Preparation of beta blocker drugs.
 To synthesize synthetic dyes.
 Useful insecticide.
 Veterinary medicine – dusting powder.
 Polyethylene naphthalene to prepare plastic bottles.
 Naphthalene sulfonic acids are used to prepare plasticizers,
natural rubbers etc.
 Naphthalene drugs to cure cough, urine infection, eye
trouble etc.

23. Anthracene (C14H10)
2
1
3
4
7
5
6
8 9
10



24. Anthracene (C14H10)
2
1
3
4
7
5
6
8
9
10


 monosubstitution (C14H9X) = 3 isomers
 Disubstitution (C14H8X2) = 15 isomers

25. Anthracene (C14H10)
 C1-C2 bond to have more double bond character
(shorter bond length)
 C2-C3 bond to have more single bond character
(longer bond length)
 From X-ray diffraction study: C1-C2 bond = 1.37 Å
C2-C3 bond = 1.42 Å
 Resonance energy 84 kcal mol-1, average 28, less
aromatic than benzene

26. Synthesis of Anthracene
(i) By Friedel Crafts reaction
(a)

27. Synthesis of Anthracene
(b)
(c)

28. Synthesis of Anthracene
(ii) By Haworth synthesis

29. Synthesis of anthracene
(iii) By Diels-Alder reaction

30. Chemical reactions
Leaves naphthalene intact
Loss of RE=84-61=23 kcal
Attack at C-1
Attack at C-2

31. Chemical reactions
Attack at C-9
Leaves two benzene intact
Loss of RE=84-72 =12 kcal
Substitution product
Addition product
Reactions preferentially occur at C-9 & C-10

32. Chemical reactions
Diels Alder reaction
Addition of one molecule of O2

33. [HNO3+H2SO4 is not used, leads formation
of 9,10 anthraqunone by oxidation]

34. Medicinal uses of Anthracene
 Anthracene glycosides are oxygenated derivatives of
pharmacological importance that are used as laxatives or
cathartics, antineoplastic agent, polycystic kidney.
 Anti-inflammatory, antibacterial, antifungal and anti-
proliferative activity.
 As natural dyes.
 Hepato-protective, nephron-protrctive, antioxidant.

35. Phenanthrene C14H10
2
1
3
4
7
5
6
8
9
10

36. Phenanthrene C14H10
2
1
3
4
7
5
6
8 9
10
2
1
3
4
7
5
6
10
8
9
monosubstitution
(C14H9X) = 5 isomers
Disubstitution
(C14H8X2) = 25 isomers

37. Position of double bond
2
1
3
4
7
5
6
8
9
10
 C9-C10 bond to have more double bond character
 RE 92 kcal/mole, 92-72=20 Kcal/mole to remove the
aromaticity of the middle ring

38. Preparation of phenanthrene
1) Howrth method

39. 2) Posher synthesis

40. Preparation of 2- alkyl phenanthrene:
Preparation of 1- alkyl phenanthrene:

41. Oxidation:
Reduction:

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

44. Medicinal uses of
Phenanthrene
 Steroid moiety contain phenanthrene nucleus which is
present in sex hormones
 Codeine has phenanthrene moiety
44

45. 2
1
3
4
6
6
5
4
2
1
5
3
Biphenyl methane or diphenyl methane
o m
m
o
p
o
m o
m
p
Diphenyl methane (C13H12)
7

46. 1. Friedel- Crafte
Methods of preparation
2. From benzophenone

47. Nitration

48. Halogenation
Oxidation

49. Stilbene
Trans-stilbebe
stable
Cis-stilbebe
unstable
(C6H5-CH=CH-C6H5)

50. C6H5CHOHCH2C6H5
Syntheis of trans-stilbene
(I)

51. Syntheis of trans-stilbene
C6H5CHOHCOC6H5
(II)
(III)
-Phenylcinnamic acid

52. Reactions of trans-stilbene
C6H5CH2CH2C6H5
Stilbebe dibromide
bibenzyl
Dphenyl acetylene

53. Synthesis of cis-stilbene
Cis-stilbebe is readily converted into trans-
stilbebe under the catalytic influence of traces of
hydrogen bromide and peroxides

54. Triphenylmethane
 Triphenylmethane (C6H6)3CH is the chromogen of a large
number of dyes. The common chromophore is the p-
quinoid structure and the auxochromes are OH,NH2 and
NR2.
 Triphenylmethane dyes are very brilliant intense colors but
fade quickly in light. Therefore, they are no longer much
used on textiles. However, they are used in large quantities
for coloring paper and typewriter ribbons.
 Synthesis:-
 Derivatives examples- crystal violet, malachite green
54