1. SAL COLLEGE OF ENGINEERING Department of Chemical Engineering ALA Subject ( Code): Organic Chemistry and Unit Processes ( ) TOPIC: Polynuclear and Heterocyclic Compounds
Guided By: Prof. Monika Swami
Prof. Disha Vyas

2. Student Name (Enrollment No.)
Puja Patel ( )
Patel Apexa ( )
Trivedi Hardi ( )
Malaviya Ankita ( )

3. Content Introduction Of Heterocyclic Compounds
Classification Of Heterocyclic Compounds
Preparation Of Heterocyclic Compounds Like- Pyrrole , Pyridine , Furan , Thiophene ,Etc.
Properties And Uses Of Heterocyclic Compounds
Introduction Of Polynuclear Compounds
Classification Of Polynuclear Compounds
Preparation Of Polunuclear Compounds Like – Naphthalene , Anthracene
Properties And Uses Of Polynuclear Compounds

4. Heterocyclic Compound
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its rings.
Heterocyclic compound are cyclic compounds in which the ring atoms are of carbon and some other element. The atom of the other element (for example: N , S , or O) is called the Hetero atom.
For example: Pyrrole, Furan , Thiophene, Indole , pyridine , Quinoline ,etc.
Thiiran
Pyridine
Furan

5. Classification of Heterocyclic compounds according to it’s membered
Three Membered Rings compounds
Four Membered Rings compounds
Five Membered Rings compounds
Six Membered Rings compounds
Seven Membered Rings compounds
Classification of Heterocyclic compounds according to it’s membered

6. 5-Membered Rings Heterocyclic Compounds
With heterocycles containing five atoms, the unsaturated compounds are frequently more stable because of aromaticity.
For examples: Furan ,Pyrrole , Thiophene , etc…..
Furan
Pyrrole
Thiophene

7. Pyrrole (Azole) C4H5N
The pyrrole ring system is important as it is found in many natural products including hemoglobin, chlorophyll, and alkaloids.
According to the resonance theory ,pyrrole is considered to be hybrid of the following five resonance structures.

8. Preparation of Pyrrole
Pyrrole is obtained :
Industrially pyrrole is obtained by passing a mixture of furan and ammonia over alumina at 400 °C.
Pyrrole can be obtained by heating
2-bytyne-1,4-diol with ammonia under pressure.
Al2O3
Furan
Pyrrole
Pyrrole

9. Properties of Pyrrole
Physical properties of Pyrrole discussed below it:
It is a colourless volatile liquid.
It’s boiling point is 131°C and melting point is -23°C.
It turns brown in the air and gradually resinifies.
Only slightly soluble in water but it is totally miscible with ether and ethanol.
Pyrrole is weakly basic in nature.
Chemical properties of pyrrole discussed below it:
Pyrrole is aromatic and more reactive than benzene.
It gives electrophilic substitution reactions such as halogenation , nitration ,etc.
It also undergoes diazotization and Reimer-Tiemann reactions, while benzene does not.

10. Uses of Pyrrole
Pyrrole is essential to the production of many different chemicals.
N-methylpyrrole is a precursor to N- methylpyrrolecarboxylic acid, a building-block in pharmaceutical chemistry.
Although there is a claim that pyrrole is used as an additive to cigarettes, it is typically listed as a constituent of tobacco smoke and not as an ingredient.
Pyrrole is also use in commercial and pharmaceuticals.

11. Furan (C4H4O)
Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen.
The class of compounds containing such rings are also referred to as furans.
Structurer Fig. Of Furan

12. Preparation of Furan
Industrially, furan is manufactured by the palladium- catalyzed decarboxylation of furfural, or by the copper- catalyzed oxidation of 1,3-butadiene.
In the laboratory, furan can be obtained from furfural by oxidation to furan-2-carboxylic acid, followed by decarboxylation.
It can also be prepared directly by thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood.

13. Properties of Furan Uses of Furan
Furan is a colourless volatile liquid.
It’s boiling point is 31.4°C and melting point −85.6 °C.
Furan having odor of chloroform.
It is insoluble in ether but soluble in most organic solvents.
Uses of Furan
Furan is used as a starting point to other specialty chemicals.

14. Thiophene (C4H4S)
Thiophene, also commonly called thiofuran, is a heterocyclic compound with the formula C4H4S.
Consisting of a flat five-membered ring, it is aromatic as indicated by its extensive substitution reactions.
Structurer fig. of Thiophene
Thiophene

15. Properties Of Thiophene
At room temperature, thiophene is a colorless liquid with a mildly pleasant odor reminiscent of benzene.
It’s boiling point is 84°C and melting point -38°C.
It is insoluble in water but freely soluble in ethanol, ether and acetone.
The high reactivity of thiophene toward sulfonation is the basis for the separation of thiophene from benzene.
Thiophene is much more reactive than benzene , thus thiophene undergoes the electrophilic substitution reactions like benzene , under moderate condition.

16. Uses of Thiophene
Thiophenes are important heterocyclic compounds that are widely used as building blocks in many agrochemicals and pharmaceuticals.
The benzene ring of a biologically active compound may often be replaced by a thiophene without loss of activity.
This is seen in examples such as the NSAID lornoxicam, the thiophene analog of piroxicam.

17. 6-Membered Heterocyclic Compounds
With heterocycles containing five atoms, the unsaturated compounds are frequently more stable because of aromaticity.
For examples: Pyridine , Quinoline ,etc…..
Pyridine
Quinoline

18. Pyridine (Azabenzene , Azine ) C5H5N
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH-) replaced by a nitrogen atom.
The pyridine ring occurs in many important compounds, including azines and the vitamins niacin and pyridoxal. Pyridine occurs in coal tar (0.1%)and in the distillate from bones (bone oil) and has been produced industrially from these sources.
According to the resonance theory, pyridine is considered to be hybrid of the following structures:

19. Preparation of Pyridine
Pyridine may be obtained by:
From acrolein by the following steps:
Formation of acrolein from acetaldehyde and formaldehyde
Condensation of pyridine from acrolein and acetaldehyde

20. Properties of Pyridine
Pyridine is colourless liquid.
It’s boiling point 115.5°C and melting point −41.6 °C.
It have characteristic unpleasant odor.
It is soluble in water and most organic solvent .
Pyridine is conventionally detected by the gas chromatography and mass spectrometry methods.
Pyridine is used as basic solvent I organic reactions.
Pyridine is used to denature alcohol.
It is also used for preparing sulfapyridine,
Uses of Pyridine

21. Quinoline (2,3-Benzopyridine) C9H7N
Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor.
It is a bicyclic heterocyclic having a benzene ring fused with a pyridine ring in 2,3-positions.
It could be considered as naphthalene in which one CH in 2- position has been replaces by N.
The official name of Quinoline is 1-Azanaphthalene.
Quinoline

22. Preparation Of Quinoline
Skraups Synthesis:- A mixture of aniline, glycerol and sulfuric acid is heated in the presence of a mild oxidizing agent such as nitrobenzene. The reaction being exothermic tends to be violent and FeSO4 is also called moderator.
Glycerol
Quinoline
Aniline

23. Properties of Quinoline
Quinoline is a colourless liquid.
It’s boiling point 238°C and melting point -15°C.
It has a disagreeable ,pyridine –like odor.
It is soluble in water and completely miscible with alcohol, ether and acetone.
Quinoline gives all the reaction of pyridine and electrophilic substitution reactions of the benzene ring.
Quinoline is used as a high-boiling basic solvent in organic reactions.
It is also used in the manufacture of pharmaceuticals, dyes and insecticides.
Uses of Quinoline

24. Polynuclear Compounds
Polycyclic aromatic hydrocarbons are hydrocarbons organic compounds containing only carbon and hydrogen that are composed of multiple aromatic rings (organic rings in which the electrons are delocalized).
Though poly- in these cases literally means "many", there is precedence in nomenclature for beginning this class and subclass with the two ring cases.
Where naphthalene would therefore be considered a simple example; beginning at three rings, examples include anthracene and phenanthrene.
Benzo[a]pyrene

25. Naphthalene C10H8
Naphthalene is an organic compound with formula C10H8  . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass.
As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings.

26. Preparation of naphthalene
Naphthalene is the most abundant (about 10%) single chemical compound present in coal-tar. The middle oil fraction(  °C) of coal-tar is chilled when naphthalene forms crystals. These are separated by centrifuging.
The crude crystals are melted and treated with sulfuric acid to remove basic impurities. The crystals are then washed with aqueous sodium hydroxide to remove phenols and excess sulfuric acid. Finally the naphthalene is distilled to get the pure product.

27. Properties Of Naphthalene
Naphthalene is a colourless solid which forms shining flaked-crystals.
It’s melting point 80.2°C and boiling point 217.9°C.
It has a familiar odor of moth balls. It is very volatile and sublimes slowly at room temperature.
Naphthalene is insoluble in water, moderately soluble in alcohol , very soluble in ether and benzene. It burns with a smoky flame.
Naphthalene gives the usual aromatic electrophilic substitution reactions.

28. Uses OF Naphthalene
Naphthalene is used as mouth repellant, in which role it has how been replaced by p- dichlorobenzene.
It is used for commercial production of phthalic anhydride.
It is used for making insecticide and tanning agent.
It is also used for manufacture of dyes, explosives and synthetic resins.

29. Anthracene C14H10
Anthracene is a solid polycyclic aromatic hydrocarbon of formula C14H10 , consisting of three fused benzene rings. It is a component of coal tar.
Anthracene is used in the production of the red dye alizarin and other dyes. Anthracene is colorless but exhibits a blue ( nm peak) fluorescence under ultraviolet light.

30. Preparation of Anthracene
Coal tar, which contains around 1.5% anthracene, remains a major source of this material. Common impurities are phenanthrene and carbazole. A classic laboratory method for the preparation of anthracene is by cyclodehydration of o-methyl- or o-methylene-substituted diary ketones in the so-called Elbs reaction.
It may also occur in the interstellar medium. More than 20% of the carbon in the universe may be associated with PAHs, including anthracene.

31. Properties of Anthracene
Anthracene is a colourless solid.
It’s melting point 217°C and boiling point 340°C.
When crystallized from benzene, it forms lustrous plates which exhibit a fine blue fluorescence.
It is insoluble in water, soluble in alcohol and ether.
Resonance energy of antharacene is considerably lower than that of benzene, it is much less aromatic than benzene.
Anthracene is used for manufacture of anthraquinone.
Anthracene is used for making dyes(Alizarin).
It is also used in smoke screens.
Uses of antharacene

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