The document discusses several polynuclear hydrocarbons including naphthalene, anthracene, phenanthrene, and diphenylmethane. It provides their structures, classification, synthesis methods, chemical reactions, and uses. Naphthalene contains two fused benzene rings and can be prepared from coal tar or through Diels-Alder reactions. Anthracene and phenanthrene both contain three fused benzene rings and can undergo halogenation, nitration, oxidation, and Diels-Alder reactions. Diphenylmethane consists of a methane molecule with two phenyl groups and can be synthesized through Friedel-Crafts condensations. These compounds are used in dyes, plastics

1. POLYNUCLEAR
HYDROCARBONS
GROUP 10 ( ROLL NO. 73 TO 80 )

2. Roll no and
Names

3. • Polynuclear hydrocarbons are
hydrocarbons, organic compound
containing only carbon and hydrogen, that
are composed of multiple aromatic rings.
Polynuclear hydrocarbons are uncharged,
non polar molecules found in coal and tar
deposits.
• They are also produced by in
complete combustion of organic matter.
• Polynuclear hydrocarbons are lipophilic and
larger polynuclear hydrocarbons are
insoluble in water. And they are abundant.
• Polynuclear hydrocarbons are consider as
possible starting material for abiologic
syntheses of materials.
• The class of polynuclear hydrocarbons are
further classified as as- the simplest are
Napthalene , having two aromatic rings and
the three ring compounds Anthracene and
Phenanthrene. 3
Introduction

4. Classification
4

5. Isolated
Linear Angular
Benzenoid
Non Benzenoid
5
Classification

6. Napthalene Anthracene Phenanthrene Diphenylmethane Triphenylmethane
6
ExamplesofSomePolynuclearhydrocarbons

7. Structure of naphthalene can be explained on
the basis of Kekule formula, orbital model,
resonance model
(1)Kekule-Type Formula: The structure of
naphthalene is given on the basis of Kekule
formula as follows:
(i) Aromatic Nature: Determination of
elemental analysis and molecular weight
shows that naphthalene has the molecular
formula CoHg. The formula of naphthalene
shows its extreme unsaturation state and
can also be expected to be very reactive.
However, naphthalene is a very stable
compound and undergoes substitution
reactions. It does not undergo addition
reaction and Phenanthrene. On complete
hydrogenation (under drastic conditions), it
gives decahydronapthalene having
molecular formula C10H18 (decalin). These
properties show that naphathalene is an
aromatic compound with five double
bonds
7
Naphthalene

8. 8
Naphthalene
(ii) Presence of a Benzene Ring with Two Side-Chains: Oxidation
of naphthalene gives phthalic acid, thus, indicating that
naphthalene contains a benzene ring having two ortho side-
chains
(iii) Presence Two Fused Benzene Rings: Erlenmeyer proposed the
structure of naphthalene from the conclusion of Kekule-type
formulas and showed the presence of two fused rings at ortho
positions
(iv) Existence of Two Monosubstituted Derivatives Confirms
Kekule-Type Formula: The Kekule-type formula shows
symmetry and allows only two isomeric monosubstituted
derivatives to be formed. The H atoms present at marked
positions (X) and (~) remain identical

9. 9
Naphthalene
Resonance Model: According to the resonance
model, structure of naphthalene can
be described as follows
i) Resonance Hybrid of Three Forms: Naphthalene
is a resonance hybrid of three canonical forms,
hence the re-electron system of naphthalene
shows a continuous delocalisation on ring system
(ii)Not All C-C Bond Lengths are Equal: Bond
length of C2-C3 bond is longer than that of C1-
C2 bond (1.36 Å) due to double bond character
i.e., shorter length of C1-C2 as it is double in
two resonance forms (I and II). However, C2-C3
bond is single in two forms (I and II) and double
in only one hence making longer length

10. Synthesis
10
Naphthalene can be prepared by the following methods
• From Coal Tar: Coal tar is the main source of naphthalene. Decalin (decahydronapthalene) in the presence of a metallic
catalyst at 180°C undergoes dehydrogenation reaction to form naphthalene.

11. Synthesis
11
• From Diel's-Alder Reaction: Furan and benzyne reacts to form the Diels-Alder adduct. However, the reactions
of Diels-Alder adduct of furan and benzyne in the presence of H/Ni produces naphthalene.
• Haworth's Synthesis: Haworth's synthesis of naphthalene involves
• Friedel-Crafts acylation of benzene

12. Synthesis
12
• From 4-Phenylbut-1-ene: A compound 4-phenylbut-1-ene when passed over redhot calcium oxide yields
naphthalene
• From 4-Phenylbut-3-enoic Acid: Heating of 4-phenylbut-3-enoic acid with sulphuric acid results in the
formation of 1-naphthol, which on further distillation with zinc dust yields naphthalene.

13. • A:- Physical Properties:-
Naphthalene is colourless, crystalline solid, m.p. 80°C, b.p. 218°C with a characteristic strong odour.
It is insoluble in water but is soluble in organic solvents, e.g. ether, benzene etc.
It is volatile and sublimes on warming.
It is also steam volatile.
It burns with sooty flame
• B:- Chemical Properties:-
Naphthalene having similar chemical properties as that of benzene, though it is less aromatic than benzene and reacts
more rapidly.
Naphthalene is having 61 kcal/mole resonance energy, in benzene which is less than twice of 36 Kcal/mole
Properties
13

14. (A)Oxidation Reactions of Naphthalene:-
When naphthalene undergoes oxidation in the presence of chromic acid, it gives 1,4-naphthoquinone. Also when it
undergoes oxidation in the presence of vanadium pentoxide
ChemicalReactions
14

15. (B) Halogenation
Bromination or chlorination of naphthalene takes place readily and does not require any Lewis acid catalyst (as in case of
benzene). Halogenation of naphthalene occurs exclusively at position-1. Substitution at 1position of naphthalene can be
explained on the basis of resonance stabilisation of the intermediate carbonation, i.e., when the halogenating agent
attack on naphthalene at 1-position, the intermediate ion formed remains more stable apparently
ChemicalReactions
15

16. (C) Friedel-Craft
While, Friedel-Craft methylation of naphthalene leads to the product mixture of the β-methyl derivatives; the Friedel-
Craft ethylation though slightly less yielding, offers on β-ethylnaphthalene
ChemicalReactions
16

17. (D) Friedel-Craft Alkylation
While, Friedel-Craft methylation of naphthalene leads to the product mixture of the β-methyl derivatives; the Friedel-
Craft ethylation though slightly less yielding, offers on β-ethylnaphthalene
ChemicalReactions
17

18. (E) Friedel-Craft Acylation
Friedel-Crafts acylation of naphtahelne depends upon nature of solvent used. If the reaction is carried out in presence of
non polar solvent such as carbon disulfide then 1-substituted product is obtained while in presence of polar solvent such
as nitrobenzene then 2-substituted product is obtained
ChemicalReactions
18

19. (F) REDUCTION:
Napthalene can be reduced partially to completely to corresponding dehydro, tetrahydro
and decahydro derivatives under a reaction conditions.
ChemicalReactions
19

20. (G) NITRATION
Napthalene undergo nitration and produces 1-nitro naphthalene which further leads to 1,5-and 1,8-dinitronapthalene
ChemicalReactions
20

21. (H) SULPHONATION:
Napthalene with sulfuric acid at lower temperature undergo sulphonation.
ChemicalReactions
21

22. (I) CHLOROMETHYLATION:
Under classical formulating condition, 1-chloromethyl Napthalene is obtain from Napthalene
ChemicalReactions
22

23. 1. As a fumigant = Napthalene has been used as a household fumigant. In a sealed
Container containing Napthlene destroy all forms of moths that attack textiles. The other
fumigant include fumigant pesticide, that repeal insect and protect the contents.
2. Laboratory uses = Molten naphthalene provides an excellent solubilizing medium
For poorly soluble aromatic compounds. It is used in industrial production of phthalic
Anhydride.
3. Wetting agent and surfactant = Alkyl naphthalene sulfonates are used as nondetergent wetting agent. Also in
agricultural chemical industries, in textile and fabric
industries.
4. Napthalene – Sulfonate polymer plasticizers are used to produce concrete and plaster
boards. Also used as dispersants in synthetic and natural rubbers, as tanning agent in
leather industries.
5. Use to produce dyes, explosive and synthetic resins.
Uses
23

24. 24
Anthracene
• Anthracene also called paranaphthalene or green
oil is a solid , aromatic and colourless
hydrocarbon
compound .
• Its molecular formula is C14H10 and it consist of
3 fused rings derived from coal ,tar or other
residues of Thermal Pyrolysis. Anthracene is a
constituent of insecticides, wood preservatives,
coating material and is also used in the synthesis
of ALIZARIN (red dye).

25. Structures
25

26. Structures
26

27. Synthesis
27

28. Synthesis
28

29. Synthesis
29

30. (A) Halogenation: Anthracene forms anthracene dihalide by reacting
with chlorine or bromine in the absence of a catalyst. Anthracene
dihalide further decomposes on heating to form 9-chloro or 9-
bromoanthracene
ChemicalReactions
30

31. B) Nitration: Anthracene forms 9-nitroanthracene and 9,10-
dinitroanthracene on treatment with conc. HNO3 in the presence of
acetic anhydride
ChemicalReactions
31

32. C) Sulphonation: Sulphonation of anthracene with concentrated
sulphuric acid at high temperature gives 2-anthracenesulphonic acid
and at low temperature gives 1anthracenesulphonic acid
ChemicalReactions
32

33. (D) Oxidation: In the presence of a strong oxidising agent (like
potassium dichromate under acidic conditions, anthracene gets
oxidised into 9,10-anthraquinone
ChemicalReactions
33

34. (E) Diels-Alder Reaction: The 9,10-positions of anthracene are highly
reactive and therefore undergo the Diels-Alder reaction with maleic
anhydride. Anthracene acts like a diene and forms
ChemicalReactions
34

35. (F) Reduction: Anthracene is reduced to 9,10-dihydroanthracene
sodium and ethanol or on catalytic hydrogenation (H2/Pd)
ChemicalReactions
35

36. Uses
36

37. • Molecular formula : C14H10
• Molar mass: 178.234 g·mol−1
• Phenanthrene a polycyclic aromatic
hydrocarbon (PAH) with formula C14H10,
consisting of three fused benzene rings.
• It is a colorless, crystal-like solid, but can
also appear yellow.
• Phenanthrene is used to make dyes, plastics
and pesticides, explosives and drugs.
• It has also been used to make bile acids,
cholesterol and steroids.
• All the fourteen carbon atom are sp2
hybridized. It occurs in coal tar in anthracene
oil fraction.
37
Phenanthrene

38. Haworth Synthesis
Synthesis
38
 Step 1: naphthalene react with succinic anhydride
in the presence of aluminium chloride to form
naphthoylpropionic acid.
 Step 2: naphthoylpropionic acid reduces to form
Naphthylbutyric acid in the presence of Zn and
HCl.
 Step 3: Naphthylbutyric acid heated with H2SO4
to give 1-keto,1,2,3,4-tetrahydrophenathrene.
 Step 4: 1-keto,1,2,3,4-tetrahydrophenathrene
reduces with Zn and HCl to form 1,2,3,4-
tetrahydrophenathrene.
 Step 5: 1,2,3,4-tetrahydrophenathrene heated
with Selenium to form Phenathrene.

39. Bardhan Sengupta Phenathrene Synthesis
Synthesis
39
• Step 1: 2-β-Phenylethylcyclohexanol reacts with
diphosphorus pentoxide to give 1,2,3,4,9,10,11,12-
Octahydrophenathrene.
• Step 2: 1,2,3,4,9,10,11,12-Octahydrophenathrene reacts
with Selenium to form Phenathrene.

40. From Dibenzyl
Synthesis
40
• Phenathrene can be obtained by passing dibenzyl through a
red hot tube.

41. From 2,2-Dimethyl-diphenyl
Synthesis
41
• Phenathrene can also be obtained by cyclohydrogenation of
2,2-Dimethyl-diphenyl using Sulphur.

42. ChemicalReaction
42

43. ChemicalReaction
43

44. ChemicalReaction
44

45. Uses
45
• Phenanthrene ring is present in various chemical compounds, which have the following medical uses
1. It is used as anticancer
2.It is used as antimalarial
3.It is used as antioxidant
4.It is used as antimicrobial
• It can be used in the manufacture of pesticides.
• After conversion processing it can be used to produce dyes and Drugs
• It is used as a stablizer of high effciency and low toxicity pesticides and smokeless powder expolsives.
• Phenanthrene quinone can be used as dyes, fungicides and polymerization inhibitors.

46. 46
Diphenylmethane
• Diphenylmethane is an organic
compound with the formula (C6H5)2CH22).
The compound consists of methane wherein
two hydrogen atoms are replaced by
two phenyl groups
• Appearance colourless oilMelting point 22 to
24 °C (72 to 75 °F; 295 to 297 K)Boiling
point264 °C (507 °F; 537 K)
The 2D chemical structure of diphenylmethane (also called
skeletal formula) is the standard notation for organic
molecules. The carbon atoms in the chemical structure of
diphenylmethane's are present at the corner(s) and
hydrogen atoms attached to the carbon atoms are not
shown. Each carbon atom is associated with hydrogen atoms
in order to provide its four bonds
The 3D chemical structure of diphenylmethane can be
explained with the ball-and-stick model displaying the 3D
position of the atoms as well as the bonds present between
them. The radius of the spheres is smaller than the rod
lengths so that a clearer view of the atoms and bonds
throughout the chemical structure model of
diphenylmethane can be obtained

47. Synthesis
47
Diphenylmethane is prepared by the following methods
1) Friedel-Crafts condensation between benzyl chloride and benzene yields diphenylmethane
2)Condensation between a molecule of formaldehyde and two molecules of benzene in the presence of
concentrated sulphuric acid yields diphenylmethane

48. Synthesis
48
3) Heating benzophenone at 160°C under pressure with hydriodic acid and red
phosphorus, the Wolff-Kishner reduction, or by LAH-AICI; yields diphenylmethane
4) Grignard reaction also yields diphenylmethane

49. Synthesis
49
3) Heating benzophenone at 160°C under pressure with hydriodic acid and red
phosphorus, the Wolff-Kishner reduction, or by LAH-AICI; yields diphenylmethane
4) Grignard reaction also yields diphenylmethane

50. ChemicalReactions
50

51. ChemicalReactions
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52. ChemicalReactions
52

53. ChemicalReactions
53

54. Uses
54
1. Diphenylmethane group is found in numerous medicinal compounds,
Therapeutic drugs.
2. Examples of It are,
Pridinol (Antiparkinson , Anti cholinergic )
Pipradrol (Mild CNS stimulant)
Fexofenadine (Antihistaminic)
Sertraline (Antidepressant)
Cyclobenzaprine (Antipsychotic)
3. Other compounds are, Antacid, Antidiarrhoeal, Antiulcer, Prebiotics,Anti emetic and Sedative.

55. 55
Triphenylmethane
• Triphenylmethane is a hydrocarbon having the
molecular formula (C6H5)3CH. It is a colourless solid
soluble in non-polar organic solvents and insoluble in
water. It is the basic skeleton of many synthetic dyes
called triarylmethane dyes. These dyes are pH indicators,
and some of them are fluorescent indicators
• Structure -pka of hydrogen on the central carbon atom is
33. The acidity of triphenylmethane is more than that of
hydrocarbons because the trityl anion is stabilized by
delocalization over three phenyl rings since,
delocalization does not occur over all the phenyl rings
due to steric effects, each ring forces the other two out
of co-planarity of the anionic carbon is parallel to the p-
orbitals of one of the phenyl rings. The trityl anion
strongly absorbs in the visible region and makes it red.
This colour is used as an indicator for maintaining the
anhydrous conditions with calcium hydride reaction
between hydride reagent and water forms solid calcium
hydroxide, which is a strong base with the ability to
generate trityl anion if hydride is completely consumed,
the solution becomes colorless.

56. Synthesis
56
• Triphenylmethane (tritane) is prepared by the following methods
• Triphenylmethane can be synthesized by friedel-crafts reaction from benzene and chloroform
with aluminium chloride catalyst
3 C6H6 + CHCl3 → ph3ch + 3 HCL (33%)
• C6H5CHO + CHO ZnCl2 (C6H5)3CH + H2O
• 2C6H5 + C6H5CHCl2 AlCl3 (C6H5)3CH + 2HCl

57. • Triphenylmethane undergoes following Reaction
• 1.It Undergoes Bromination to yeild triphenylmethyl bromide
• 2.It undergoes Oxidation to yeild Triphenylcarbinol
• 3. Triphenylmethyl react with sodium to form Triphenylmethyl sodium
ChemicalReaction
57

58. Uses
58
I. Triphenylmethane dyes are used in medicine and experimental biology. E.g. in cytology, histology and microbiology to
stain cells.
II. Malachite green and Crystal Violet are some Dyes possessing antibacterial, antifungal and antiprotozoal properties.
III. These are also used as medical disinfectants.
IV. Some of the Triphenylmethane dyes are used as pH indicator and some display Fluorescence.

59. Thank You