Introduction of poly-cyclic compounds, resonance, molecular orbital structure, physical properties, preparation, reaction and uses of napthalene, anthracene, phenanthrene, napthaquinone, napthol, napthylamine, 9,10 anthraquinone and phenanthrequinone.

1. Polynuclear hydrocarbons
Mr.Mote G.D.
Assistant Professor
Annasaheb Dange college of
B.Pharmacy, Ashta

2. CONTENTS
• INTRODUCTION
• MOLECULAR ORBITAL STRUCTURE
• RESONANCE STRUCTURE
• REACTIVITY
• SYNTHESIS
• REACTIONS
• USES

3. Polynuclear Aromatics
Phenanthrene
AnthraceneNaphthalene

4. Molecular orbital structure of naphthalene

5. 5
 Resonance energy of A = 61 kcal mol-1
 Resonance energy of B = 84 kcal mol-1
 Resonance energy of C = 92 kcal mol-1
 Resonance energy of benzene = 36 kcal mol-1
Aromatic character of naphthalene, anthracene
and phenanthrene

6. 6
Resonance structures and bond lengths of
naphthalene, anthracene and phenanthrene
There are n+1 principal resonance structures for polynuclear
aromatic hydrocarbon containing n benzene rings fused
together in a linear manner.
Bond length
Double bond character
The different carbon-carbon bond lengths reveal the
decreased aromaticity of fused polynuclear aromatic
hydrocarbons.
Phenanthrene is an angular polynuclear aromatic
hydrocarbon.

7. Resonance Forms of Naphthalene
Resonance Forms of Anthracene
Resonance Forms of Phenanthrene

8. E
H E
H E
C-1 Attack
Reactivity of Anthracene
At C-1 and C-2 attack napthalene system will retained &
get less stable product

9. E
H
E
C-2 Attack
E
H E
H
E
Nu
E
H
H NU
C-9 Attack= more susceptibility at c-9 is preferable .
Hence electrophilic substitution observed at C-9
Reactivity of Anthracene

10. Conclusion on reactivity
• Naphthalene undergoes electrophilic
substitution at C-1 position
• Anthracene and phenanthrene are
undergoes electrophilic substitution at C-9
position.

11. Why is EAS in naphthalene mostly to the alpha-position?
α
β

12. 1
2
3
45
6
7
8
9
10
Napthalene

13. Naphthalene: nomenclature:
Mono substituted: α- 1-
β- 2-
Special names:
NO2
2-nitronaphthalene
-nitronaphthaleneβ
OH NH2 SO3H
-naphthol -naphthylamine -naphthalenesulfonic acidα α α
also β−

14. flat, sp2
4i + 2 = 10 e-
aromatic
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.

15. Synthesis of napthalene
1. From petroleum: extracton with copper at 680°c.
2. From 4-phenyl -1-butene: 4-phenyl -1-butene is passed over red hot
calcium oxide to form napthalene
1-(but-3-enyl)benzene
red hot CaO H2

16. 3. Synthesis of napthalene from
4-Phenyl 3-butenoic acid
C
O
HO
H -H2O
H2SO4
O
H
Rearrangement
OH
Zn
ZnO

17. 4. Haworth Synthesis of naphthalene
O
O
O
O
HO2C
AlCl3
+
Zn(Hg)
HCl
HO2C
HF or
PPA
O
Zn(Hg)
HCl
Pd
CO2, heat

18. Benzene
H2C
H2C
C
C
O
O
AlCl3
C
O
CH2
CH2
C
O
HO
Benzoylpropionic acid
Zn/HgHCl
CH
H
CH2
CH2
C
O
HO
H
Phenyl butyric acid
H2SO4
O
Tetralone
Zn/HgHCl
Tetralin
Pd
O
HO
H
4-Phenyl -3- Butenoic acid
H2SO4
-H2O
Petroleum
Cu
680°C
H2
C
CH2
CH
H2C
4-Phenyl -1- butene
CaO
Synthesis methods
Of napthalene

19. Benzene
C
C
O
O
Phthalic anhydride
C
O
OH
H
Benzoyl benzoic acid
H2SO4
O
O
9 10 anthraquinone
Zn
Distill
Anthracene
Zn
O
O
9,10 anthraquinone
CrO3
O
O
H
H adduct
O
O
Napthaquinone
H2C
CH
CH
H2C
1,3 Butadiene
CH2 Cl
H
Benzyl chloride
H
H2CCl
Benzyl chloride
Freidal Craft alkylation
AlCl3
C
O
CH3
o-methyl benzophenone
Elbe synthesis
450°C
Diels alder reaction
Synthesis methods of Anthracene
Haworth

20. Benzene
H2C
H2C
C
C
O
O
AlCl3
C
O
CH2
CH2
C
O
HO
Benzoylpropionic acid
Zn/HgHCl
CH
H
CH2
CH2
C
O
HO
H
Phenyl butyric acid
H2SO4
O
Tetralone
Zn/HgHCl
Tetralin
Pd
H2C
H2C
C
C
O
O
CO CH2 CH2 COOH
CH2 CH2 CH2
C
OHO
H
Zn/Hg
H2SO4-H2O
O
Zn/HgHCl
Pd
Phenanthrene
C
C
O
O
O
Phthalic anhydride
C
O
OH
H
Benzoyl benzoic acid
AlCl3
O
O
9 10 anthraquinone
ZnDistil
Anthracene
H2SO4-H2O
Haworth synthesis

21. H2
C
CH2
CH
H2C
4-Phenyl -1- butene
CaO
O
HO
H
4-Phenyl -3- Butenoic acid
H2SO4
-H2O
H2C
H2C
C
C
O
O
Benzene
Petroleum
Cu
680°C
AlCl3
C
O
CH2
CH2
C
O
HO
Zn/HgHCl
CH
H
CH2
CH2
C
O
HO
H
H2SO4
O
Pd
Zn/HgHCl
Tetralone
Tetralin
Benzoylpropionic acid
Synthesis of napthalene

22. O
O
H2C
CH
CH
H2C
O
O
H
H
CrO3
O
O
Zn
1,3 Butadiene
Napthaquinone
CH2 Cl
H
Benzyl chloride
H
H2CCl
Benzyl chloride
Anthracene
9,10 anthraquinone
adduct
C
O
CH3
o-methyl benzophenone
450°CAlCl3
Benzene
C
C
O
O
O
Phthalic anhydride
C
O
OH
H
Benzoyl benzoic acid
H2SO4
O
O
9 10 anthraquinone
Zn
Distill
Synthesis of anthracene
Freidal Craft alkylation
Haworth synthesis
Elbe synthesis
Diels- alder synthesis

23. Properties of napthalene
• It is colorless crystaline solid. Melts at 82°c
• It is insoluble in water
• It has mouth ball like odour

24. Uses of Napthalene
• Napthalene as moth balls has been used to protect woolen
goods from moths.
• It is also used for increasing illuminating power of coal
gas.
• Napthalene is used in the manufacturing of phthaleic
anhydride, carbaryl for insectiside, 2-napthol, dyes, some
medicinal products.
• Propranolol,-antihypertensive drugs.
• Tolnapthate-Antifungal
• Menadione-Vitamin-K
• Naphazoline- Vasoconstrictor for rhinitis and sinusitis

25. Substituted naphthalenes via Haworth synthesis:
CH3
O
O
O
+
AlCl3
CH3
C
O
COOH
CH3
beta-
O
+ RMgX
OHR
H+
Pd, CO2
heat
a) use a substituted benzene G = -R, -X, -OCH3
b) Grignard
RR
alpha-

26. O
HO2C
R'OH, H+
O
R'O2C
RMgX H2O
R OH
R'O2C
H+, heat
R
HO2C
R
alpha-

27. Naphthalene, reactions:
1) oxidation:
O
O
O
O
O
CrO3
HOAc, 25o
O2, V2O5
460-480o
1,4-naphthoquinone
phthalic anhydride

28. 28
(1) Oxidation
 Oxidation by V2O5 is important industrial process (naphthalene is
available from coal tar).
 Vitamins K1 and K2 are derivatives of 1,4-naphthoquinone.
 Because of this tendency to form quinones, it is not always feasible
to prepare naphthalenecarboxylic acids by oxidation of methyl side
chains.

29. Note: Because naphthalene is sensitive to oxidation, you cannot
make naphthoic acids via oxidation of a side chain.
[oxid.]
CH3 CH3
O
O
CCH3
O
NaOI
COOH

30. 2. Reduction:
Na, EtOH
78o
Na, i-PeOH
132o
(xs) H2, Pt
heat, pressure
1,4-dihydronaphthalene
tetrahydronaphthalene
(tetralin)
decalin

31. 31
(3) Electrophilic susbstitution reactions
Reactions of naphthaleneReactions of naphthalene
1-Substitution versus 2-substitution
Number of resonance structures Aromatic sextet is retained
(benzene has large R. E.)
Fries rule: The most stable arrangement of a polynuclear
compound is that form which has the maximum number
of rings in the benzenoid condition.
Carbocation and T.S. resulting from attack at the 1-position
are much more stable than those resulting from attack
at the 2-position . Therefore, 1-susbstitution will be
preferred.

32. 3. Electrophilic Aromatic Substitution:
a) nitration
HNO3
NO2
b) sulfonation
H2SO4
H2SO4
80o
1600
SO3H
SO3H
c) halogenation
Br2
CCl4
Br
nocatalyst required

33. Electrophilic aromatic substitution (cont.)
d) Friedel-Crafts alkylation
e) Friedel-Crafts acylation
polyalkylation!
CH3COCl, AlCl3
non-polar solvent
CH3COCl, AlCl3
nitrobenzene
C
C
O CH3
CH3
O

34. EAS in syntheses of substituted naphthalenes:
Alpha-substitution via halogenation or nitration.
Br MgBr
NO2
NH2
Br2
CCl4
HNO3
Mg
H2/Ni

35. Beta-substitution via high temp sulfonation or Friedel-Crafts
acylation in nitrobenzene.
SO3H ONa
OHNH2
C
CH3
O
COOH
C
NH2
O
NH2
OH-, 3000
H+
NH3
heat,pressure
OI- SOCl2; then NH3
OBr-

36. 36
Summary of naphthalene reactionsSummary of naphthalene reactions

37. 2
3
4
1
10
9
5
6
7
8
anthracene
Heat of hydrogenation is
-84 Kcal lower than expected.
2 x -36 = -72
-86 - (-72) = -12 Kcal/mole to
remove the middle ring's
aromaticity.

38. 3
2
1
4
10
9
8
7
6
5
3
2
1
4
109
8
7
6 5
Phenanthrene
14 pi e-
, total
of five resonace
structures
Heat of hydrogenation is -92 Kcal/mole lower than
predicted.
2 x -36 = -72
-92 -(-72) = -20 Kcal/mole to remove the aromaticity
of the middle ring.

39. 1. Elbe synthesis
• The conversion of a diaryl ketone containing a methyl or methylene group ortho to the
carbonyl function is known as the Elbs Reaction.
• when o-methylbenzophenone is heated at 450°C, anthracene is formed.
C
O
CH3
o-methyl benzophenone
450°C
H2O

40. 2. Friedel-Crafts Reactions
• Benzyl chloride reacts with itself to form
9,10-dihydroanthracene,which readily loses
two hydrogen atoms to yield anthracene.
CH2 Cl
H
Benzyl chloride
H
H2CCl
Benzyl chloride
AlCl3
-2HCl
H H
H H

41. 3. Diels alder reaction
O
O
H2C
CH
CH
H2C
O
O
H
H
CrO3
O
O
Zn
1,3 Butadiene
Napthaquinone

42. 4. Haworth synthesis of anthracene
O
O
HO2C
O
O
O
O
+
AlCl3
H2SO4
Zn(Hg)
HCl
Pd, CO2, heat
phthalic anhydride
benzene
2-benzoylbenzoic acid
anthracene-9,10-dione
9,10-dihydroanthracene
anthracene

43. Haworth synthesis of phenanthrene
O
O
COOH
O
O
+
AlCl3
succinic anhydride Zn(Hg), HCl
HOOC
naphthalene 5-(naphthalen-1-yl)-5-oxopentanoic acid
O
H2SO4
Zn(Hg)
Pd
CO2
phenanthrene
2,3-dihydrophenanthren-4(1H)-one
4-(naphthalen-2-yl)butanoic acid1,2,3,4-tetrahydrophenanthrene

44. K2Cr2O7
H+
K2Cr2O7
H+
O
O
OO
9,10-antraquinone
9,10-penanthrone
Oxidation:

45. Na, heat
EtOH
Na,heat
i-PeOH
9,10-dihyroanthracene
9,10-dihydrophenanthrene
Reduction:

46. 3HC C
O
Cl
C
O
Cl
NO2
Cl2 IN CCl4
Cl
HNO3
9-CHLORO ANTHRACENE
9-NITRO ANTHRACENE
9-ACETYL ANTHRACENE
H2SO4
SO3H
1-ANTHRACENE SULPHONIC ACID
Electrophilic substitution reactio n of Anthracene

47. 3HC C
O
Cl
C
NO2 Cl
O
CH3
SO3H
2-PHENANTHRENE SULPHONIC ACID
9-CHLORO PHENANTHRENE
9-NITRO PHENANTHRENE
9-ACETYL PHENANTHRENE
Electrophilic substitution of Phenanthrene

48. Cl2
CCl4
Cl
AlCl3H3C
C
O
Cl
C
O
CH3
HNO3
(CH3CO)2O
NO2
H2SO4
SO3HNa/C2H5OH
O
Na2Cr2O7
H2SO4
CH3CH2Cl/2Na
CH2CH3
CH2CH3
HC
HC
C
C
O
O
O
HC
HC
C
C
O
O
O
REACTIONS OF ANTHRACENE

49. Cl2
CCl4
AlCl3H3C
C
O
Cl
HNO3
(CH3CO)2O
H2SO4
Na/C2H5OH
Na2Cr2O7
H2SO4
Cl
CO
CH3
O2N
CH3
O O
Reactions of Phenanthrene

50. H2C
H2C
C
C
O
O
Benzene
AlCl3
C
O
CH2
CH2
C
O
HO
Zn/HgHCl
CH
H
CH2
CH2
C
O
HO
H
H2SO4
O
Pd
Zn/HgHCl
Tetralone
Tetralin
Phenyl butyric acid
Benzoylpropionic acid
Napthalene
H2C
H2C
C
C
O
O
CO CH2 CH2 COOH CH2 CH2 CH2
C
OHO
H
H2SO4-H2O
O
Zn/HgHCl
Pd
C
C
O
O
O
AlCl3
C
O
OH
H
O
O
H2SO4
ZnDistil
Phthalic anhydride
Benzene
Benzoyl benzoic acid 9 10 anthraquinone
Anthracene
Phenanthrene
Howorth Synthesis

51. Uses of anthracene and
Phenanthrene
• A. Anthracene-Synthesis of anthrquinone
• Anthraquinone is used in the manufacture of alizarin and
several other dyes.
• Purgative drugs-Senna, Rhubarb, Cascara
• Dithrol-Antifungal
• B. phenanthrene is used as carcinogenic
• Steroid moiety contain phenanthrene nucleus.
• Sex hormones, Bile acids.
• Steroid used as oral contraceptive and antiinflamatory
agent
• Cardiac glycosides, Morphine , codeine

52. Synthesis of diphenyl methane
Synthesis of triphenyl methane

53. Derivatives of diphenyl methane
C
H
OH
benzhydrol
C
O
Benzophenone
Uses of diphenyl metahne and triphenyl methane
Diphenyl methane
1. Polymer
2. Synthesis of acetaminophen
3. Dye
4. Synthetic steroid
5. Benzophenone
6. Diphenyl carbinol
7. Fluorene
Triphenyl methane
1.Malachite green
2.Crystal violet
3.Other dyes.

54. Reactions of Diphenyl Methane
CH2
HNO3
CH2
NO2
Cl2
CH2
Cl
450°c
Red hot
tube
C
O
KMnO4
benzophenone
1-benzyl-4-nitrobenzene
1-benzyl-4-chlorobenzene

55. CH
Cl2
CH
CH
HNO3
NO2
NO2
O2N
Cl
Cl
Cl
tris(4-nitrophenyl)methane
(3-chlorophenyl)bis(4-chlorophenyl)methane
Reactions of triphenyl methane