Aromatic compounds

The cyclic organic compounds which contain at least one aromatic ring that resembles benzene are called aromatic compounds.

Example :

1) Benzene

2) Naphthalene

Aryl group and Phenyl group

Aryl group :

Aromatic Hydrocarbons are called Arenes.

Aryl group is derived from arenes and represented as Ar.

Phenyl group :

C₆H₅is called Phenyl group.

Benzene was originally called Phene and the Phenyl group is derived from benzene.

Characteristics of Aromatic compound

1) Aromatic compounds contain higher percentage of carbon than corresponding aliphatic hydrocarbons (alkanes, alkenes,alkynes)

2) Aromatic compounds are more stable than alkanes.

3) Aromatic compounds inspite of the presence of double bond readily undergoes substitution reactions.

4) Aromatic compounds due to higher percentage of carbon content, burn with sooty flame.

Some important aromatic compound

1) Benzene

2) Naphthalene

3) Anthracene

4) Benzaldehyde

5) Benzoic acid

6)Aniline

7) Toluene

8) Pyridine

9) Chlorobenzene

10) Phenol

11) Nitrobenzene

12) Thiophene

13) Benzene sulphonic acid

14) Furan

15) Anisole

Resonating Structures of Benzene

Preparation method Of benzene

1) When acetylene is reacted with Red hot iron tube at 873 k, it undergoes cyclic polymerization, gives the formation of benzene.

2) When Sodium benzoate is reacted with sodium hydroxide undergoes decarboxylation it gives the formation of benzene.

3) When Phenol is reacted with zinc dust, it undergoes reduction and gives the formation of benzene.

Reactions of benzene

1) When benzene is reacted with chlorine in presence of UV light or bright sunlight it gives formation of benzene hexachloride.

2) When Benzene is reacted with chlorine in presence of Anhydrous AlCl3 it gives the formation of Chlorobenzene

3) When Benzene is reacted with bromine in presence of ferric bromide FeBr3 it gives the formation of Bromobenzene

4) When Benzene is reacted with hydrogen in presence of Ni catalyst it gives the formation of Cyclohexane.

5) When Benzene is reacted with Ozone it gives the formation of Benzene triozonide which on hydrolysis with water in presence of zinc gives three molecules of Glyoxal.

6) When Benzene is reacted with concentrated nitric acid in presence of concentrated H₂SO₄ it gives the formation of Nitrobenzene.

7) When Benzene is reacted with Sulfuric acid in presence of fuming H2SO4 it gives the formation of benzene sulphonic acid.

Friedel-craft's alkylation reaction

1) When Benzene is reacted with methyl chloride in presence of anhydrous AlCl₃ it gives the formation of Toluene.

2) When Benzene is reacted with ethyl chloride in presence of anhydrous AlCl₃ it gives the formation of Ethyl benzene

Friedel-craft's acylation reaction

1)When Benzene is reacted with Acetyl chloride in presence of Anhydrous AlCl₃ it gives the formation of Acetophenone

2) When Benzene is reacted with Acetic anhydride in presence of Anhydrous AlCl₃ it gives the formation of Acetophenone

Uses of aromatic compound

1) Aromatic compounds play important role in biochemistry of all living things.

2) Aromatic compounds are important in industry.

3) Toluene is used for glues,paints,thinners and nail-polish remover.

4) It is also used for printing process.

5) naphthalene used for pesticide.

6) Benzoic acid used as food preservatives.

7) Phenol is used in preparation of cosmetics.