Polynuclear hydrocarbon

By students of Sir Dr. M.S. GOSAVI COLLEGE OF PHARMACEUTICAL EDUCATION AND RESEARCH, NASHIK.

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

2. Roll no and
Names

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

4. Classification
4

5. IsolatedLinear Angular
Benzenoid
Non Benzenoid
5
Classification

6. Napthalene Anthracene Phenanthrene DiphenylmethaneTriphenylmethane
6
Examples of Some Polynuclearhydrocarbons

7. Structure of naphthalene can be explained on
the basis of Kekuleformula, 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 unsaturationstate 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 decahydronapthalenehaving
molecular formula C10H18 (decalin). These
properties show that naphathaleneis 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 phthalicacid, thus, indicating that
naphthalene contains a benzene ring having two orthoside-
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 MonosubstitutedDerivatives 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 delocalisationon 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 benzynereacts to form the Diels-Alder adduct. However, the reactions
of Diels-Alder adduct of furan and benzynein the presence of H/Ni produces naphthalene.
•Haworth's Synthesis: Haworth's synthesis of naphthalene involves
•Friedel-Crafts acylationof benzene

12. Synthesis
12
•From 4-Phenylbut-1-ene: A compound 4-phenylbut-1-ene when passed over redhotcalcium oxide yields
naphthalene
•From 4-Phenylbut-3-enoic Acid: Heating of 4-phenylbut-3-enoic acid with sulphuricacid 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
Chemical Reactions
14

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

16. (C) Friedel-Craft
While, Friedel-Craft methylationof naphthalene leads to the product mixture of the β-methyl derivatives; the Friedel-
Craft ethylationthough slightly less yielding, offers on β-ethylnaphthalene
Chemical Reactions
16

17. (D) Friedel-Craft Alkylation
While, Friedel-Craft methylationof naphthalene leads to the product mixture of the β-methyl derivatives; the Friedel-
Craft ethylationthough slightly less yielding, offers on β-ethylnaphthalene
Chemical Reactions
17

18. (E) Friedel-Craft Acylation
Friedel-Crafts acylationof naphtahelnedepends 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
Chemical Reactions
18

19. (F) REDUCTION:
Napthalenecan be reduced partially to completely to corresponding dehydro, tetrahydro
and decahydroderivatives under a reaction conditions.
Chemical Reactions
19

20. (G) NITRATION
Napthaleneundergo nitration and produces 1-nitro naphthalene which further leads to 1,5-and 1,8-dinitronapthalene
Chemical Reactions
20

21. (H) SULPHONATION:
Napthalenewith sulfuric acid at lower temperature undergo sulphonation.
Chemical Reactions
21

22. (I) CHLOROMETHYLATION:
Under classical formulating condition, 1-chloromethyl Napthaleneis obtain from Napthalene
Chemical Reactions
22

23. 1. As a fumigant = Napthalenehas been used as a household fumigant. In a sealed
Container containing Napthlenedestroy 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 solubilizingmedium
For poorly soluble aromatic compounds. It is used in industrial production of phthalic
Anhydride.
3. Wetting agent and surfactant = Alkyl naphthalene sulfonatesare used as nondetergentwetting agent. Also in
agricultural chemical industries, in textile and fabric
industries.
4. Napthalene–Sulfonatepolymer 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
•Anthracenealso called paranaphthaleneor 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. Anthraceneis 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
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29. Synthesis
29

30. (A) Halogenation: Anthraceneforms anthracenedihalideby reacting
with chlorine or bromine in the absence of a catalyst. Anthracene
dihalidefurther decomposes on heating to form 9-chloro or 9-
bromoanthracene
Chemical Reactions
30

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

32. C) Sulphonation: Sulphonationof anthracenewith concentrated
sulphuricacid at high temperature gives 2-anthracenesulphonic acid
and at low temperature gives 1anthracenesulphonic acid
Chemical Reactions
32

33. (D) Oxidation: In the presence of a strong oxidisingagent (like
potassium dichromate under acidic conditions, anthracenegets
oxidisedinto 9,10-anthraquinone
Chemical Reactions
33

34. (E) Diels-Alder Reaction: The 9,10-positions of anthraceneare highly
reactive and therefore undergo the Diels-Alder reaction with maleic
anhydride. Anthraceneacts like a dieneand forms
Chemical Reactions
34

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

36. Uses
36

37. •Molecular formula : C14H10
•Molar mass:178.234 g·mol−1
•Phenanthreneapolycyclic aromatic
hydrocarbon(PAH) with formula C
14H
10,
consisting of three fusedbenzene rings.
•It is a colorless, crystal-like solid, but can
also appear yellow.
•Phenanthreneis 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 succinicanhydride
in the presence of aluminium chloride to form
naphthoylpropionicacid.
Step 2: naphthoylpropionicacid reduces to form
Naphthylbutyricacid in the presence of Zn and
HCl.
Step 3: Naphthylbutyricacid 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 HClto form 1,2,3,4-
tetrahydrophenathrene.
Step 5: 1,2,3,4-tetrahydrophenathrene heated
with Selenium to form Phenathrene.

39. BardhanSenguptaPhenathreneSynthesis
Synthesis
39
•Step1:2-β-Phenylethylcyclohexanolreactswith
diphosphoruspentoxidetogive1,2,3,4,9,10,11,12-
Octahydrophenathrene.
•Step2:1,2,3,4,9,10,11,12-Octahydrophenathrenereacts
withSeleniumtoformPhenathrene.

40. From Dibenzyl
Synthesis
40
•Phenathrenecanbeobtainedbypassingdibenzylthrougha
redhottube.

41. From 2,2-Dimethyl-diphenyl
Synthesis
41
•Phenathrenecanalsobeobtainedbycyclohydrogenationof
2,2-Dimethyl-diphenylusingSulphur.

42. Chemical Reaction
42

43. Chemical Reaction
43

44. Chemical Reaction
44

45. Uses
45
•Phenanthrenering 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 stablizerof high effciencyand low toxicity pesticides and smokeless powder expolsives.
•Phenanthrenequinonecan be used as dyes, fungicides and polymerization inhibitors.

46. 46
Diphenylmethane
•Diphenylmethaneis anorganic
compoundwith theformula(C6H5)2CH22).
The compound consists ofmethanewherein
two hydrogen atoms are replaced by
twophenyl groups
•Appearance colourlessoilMeltingpoint 22 to
24°C (72 to 75°F; 295 to 297K)Boiling
point264°C (507°F; 537K)
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'sare 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 diphenylmethanecan 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
diphenylmethanecan be obtained

47. Synthesis
47
Diphenylmethaneis 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 sulphuricacid yields diphenylmethane

48. Synthesis
48
3) Heating benzophenoneat 160°C under pressure with hydriodicacid and red
phosphorus, the Wolff-Kishnerreduction, or by LAH-AICI; yields diphenylmethane
4) Grignard reaction also yields diphenylmethane

49. Synthesis
49
3) Heating benzophenoneat 160°C under pressure with hydriodicacid and red
phosphorus, the Wolff-Kishnerreduction, or by LAH-AICI; yields diphenylmethane
4) Grignard reaction also yields diphenylmethane

50. Chemical Reactions
50

51. Chemical Reactions
51

52. Chemical Reactions
52

53. Chemical Reactions
53

54. Uses
54
1.Diphenylmethanegroup 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,Antiemetic and Sedative.

55. 55
Triphenylmethane•Triphenylmethaneis a hydrocarbon having the
molecular formula (C6H5)3CH. It is a colourlesssolid
soluble in non-polar organic solvents and insoluble in
water. It is the basic skeleton of many synthetic dyes
called triarylmethanedyes. These dyes are pH indicators,
and some of them are fluorescent indicators
•Structure -pkaof hydrogen on the central carbon atom is
33. The acidity of triphenylmethaneis more than that of
hydrocarbons because the tritylanion is stabilized by
delocalization over three phenyl rings since,
delocalization does not occur over all the phenyl rings
due to stericeffects, each ring forces the other two out
of co-planarity of the anionic carbon is parallel to the p-
orbitalsof one of the phenyl rings. The tritylanion
strongly absorbs in the visible region and makes it red.
This colouris 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 tritylanion if hydride is completely consumed,
the solution becomes colorless.

56. Synthesis
56
•Triphenylmethane (tritane) is prepared by the following methods
•Triphenylmethane can be synthesized byfriedel-crafts reaction frombenzene andchloroform
withaluminium chloride catalyst
3 C
6H
6+ CHCl
3→ ph
3ch + 3 HCL (33%)
•C6H5CHO + CHO ZnCl2 (C6H5)3CH + H2O
•2C6H5+ C6H5CHCl2AlCl3(C6H5)3CH + 2HCl

57. •Triphenylmethaneundergoes following Reaction
•1.It Undergoes Brominationto yeildtriphenylmethylbromide
•2.It undergoes Oxidation to yeildTriphenylcarbinol
•3. Triphenylmethylreact with sodium to form Triphenylmethylsodium
Chemical Reaction
57

58. Uses
58
I.Triphenylmethanedyes 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 antiprotozoalproperties.
III.These are also used as medical disinfectants.
IV.Some of the Triphenylmethanedyes are used as pH indicator and some display Fluorescence.

59. Thank You